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Pet Bird Toxicity and Related Environmental Concerns

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Pet Bird Toxicity and Related Environmental Concerns

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Birds may be exposed to toxins through various sources in their everyday environment. Toxicity may occur through inhalation or oral or dermal exposures. Clinicians diagnose and treat these toxicities in an effort to correct the disease of the individual patient. Recognition of toxicity in the avian patient has further significance as it relates to the patient's environment, including the health of other animals, humans, and the ecosystem. While some toxicities, such as lead and zinc toxicosis, are well-documented in avian species, others are limited to anecdotal reports and extrapolation from other species. Continued research is needed in this area of avian medicine to expand our knowledge and improve our ability to diagnose and treat toxic conditions in birds.
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Pet Bird Toxicity and Related
Environmental Concerns
Teresa L. Lightfoot, DVM, DABVP–Avian*,
Julie M. Yeager, DVM
Department of Avian and Exotic Medicine, Florida Veterinary Specialists,
3000 Busch Lake Boulevard, Tampa, FL 33614, USA
Avian toxicology is significant on several levels. For the individual bird
and its owner, the veterinarian’s knowledge of potential toxins and their
treatment may be life saving. To occupants of the same environment (be
that a household or an ecosystem) identification of potential toxins may
halt or prevent illness in other exposed individuals. To the greater commu-
nity, neighborhood, ecosystem, and planet, identification of a toxin, its
source, and its physiologic effects on selected populations may provide
information and impetus for change that will benefit the environment and
all its inhabitants.
Birds, cats, and dogs historically have served as sentinels for human tox-
icity in the environment. Birds were used as sentinels for coal miners in the
United States and England until the middle of the last century. Dangerous
levels of carbon monoxide, methane, and other poisonous gasses would
affect sentinel canaries before they affected the miners, thus warning them
of a dangerous environment. In Japan in 1956, the erratic behavior of feral
and outdoor cats that had consumed mercury-contaminated fish was widely
noted and reported. This behavior in cats preceded the recognition of
human behavioral abnormalities as a result of mercury ingestion. In north-
western Ontario in the 1970s, a river system was contaminated with mercury
from a chloralkali plant. Pet cats became ill when they consumed fish from
this contaminated river, thereby serving as inadvertent sentinels for this tox-
icity. Another example of a toxin for which pets serve as sentinels for human
toxicity is asbestos. Mesothelioma is a neoplasia of humans and dogs caused
by asbestos exposure. The latency period between asbestos exposure and
mesothelioma development in people may be more than 25 years; but in
* Corresponding author.
E-mail address: lightfoott@aol.com (T.L. Lightfoot).
1094-9194/08/$ - see front matter Ó2008 Elsevier Inc. All rights reserved.
doi:10.1016/j.cvex.2008.01.006 vetexotic.theclinics.com
Vet Clin Exot Anim 11 (2008) 229–259
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dogs it has been shown to average 5 to 7 years. Pet dogs with spontaneous
mesothelioma have been used to identify environmental exposures that
might increase their owner’s risk of developing this neoplasia.
Pets may be sensitive sentinels of lead poisoning in children. In Illinois,
the children and the pet dogs of families living in questionable housing con-
ditions were tested for exposure to lead. A strong correlation was found be-
tween lead levels in the serum of the dogs and the children.
As our knowledge of avian toxicology increases, so likely will knowledge
regarding the interrelationship of toxicity and its sequelae in birds and hu-
mans. As practitioners, we need to be aware of these potential links, share
our findings with our colleagues, both veterinary and human, and inform
owners of potential concerns with human health.
On a larger environmental scale, our wild birdsdcoastal and pelagic sea-
birds, raptors, songbirdsdare objects of studies that detect dangerous levels
of heavy metals, pesticides, and other chemicals in bodies of water and sour-
ces of food for both animals and humans. Affects on their health and fecun-
dity are of conservational import, and have great significance for the
environment and human health.
Authors’ Note: For purposes of this article, the emphasis will be on
toxins that are most commonly encountered in pet birds and those that
are specific to avian species. The vast number of possible toxins makes
a complete listing prohibitive. Although toxicity may not have been re-
ported in birds for various agents, poison control organizations can aid
the veterinarian in determining the danger of potential toxins and recom-
mend treatment that has been documented in other species (Box 1 for
a list of poison control resources). General recommendations for initial
treatment of toxicities based on the route of exposure appear in Fig. 1.
This discussion of avian toxicology addresses toxins at three different
confidence levels:
1. Toxins to which birds are known, through controlled studies, to be
sensitive.
2. Toxins that are generally poisonous to vertebrate species, and to which
empirically birds have been noted to be susceptible, but for which there
are no controlled studies in avian species.
3. Anecdotal reports of toxicities in birds.
Airborne/inhalant toxins
Polytetrafluoroethylene
The avian respiratory tract is particularly sensitive to airborne irritants
and toxins because of specific anatomic and physiologic features of birds
[1]. Polytetrafluoroethylene (PTFE) is one of the most common causes of
airborne toxicity encountered in pet avian species. This product is found
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Box 1. Poison control contacts
American Association of Poison Control Centers, 1-800-222-
1222
ASPCA Animal Poison Control Hotline, 888-426-4435 ($45
consultation fee), www.aspca.org/apcc. Web site features lists
of toxic and nontoxic plants.
Toxicity to Pets, Livestock, and Wildlife: Contact Centers for
Disease Control and Prevention (CDC), 800-232-4636, http://
www.atsdr.cdc.gov/consultations/
Angell Animal Poison Control Hotline, 1-877-2ANGELL ($55.00
consultation fee)
Fig. 1. General approach to treating avian toxicities. Note: This is a general treatment
approach. Please refer to specific toxins or consult poison control for more specific treatment.
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PET BIRD TOXICITY AND RELATED ENVIRONMENTAL CONCERNS
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in nonstick cookware, irons, covers for ironing boards, and heat lamps,
among others [2]. When PTFE is heated above 280C it decomposes into
particulates and fluorinated, acidic gasses [3,4] that are toxic when inhaled.
Clinical signs may include dyspnea, incoordination, weakness, coma, and
death [5]. Pulmonary lesions include severe edema, hemorrhage, and necro-
sis [3]. Deposition of particulate matter in pulmonary tissues may also be
noted on histopathology [3]. Treatment consists of oxygen therapy, bron-
chodilators, anti-inflammatory drugs, diuretics, antimicrobials to prevent
secondary infection, and analgesics. In clinically affected birds, the progno-
sis is generally poor. Smaller birds such as budgerigars seem to be most
sensitive to the effects of PTFE toxicity [1].
Humans may also be affected after exposure to vaporized PTFE prod-
ucts, developing a syndrome called Polymer Fume Fever, which often
consists of flu-like symptoms and noncardiogenic pulmonary edema [6–8].
Smoke
Smoke is another source of airborne toxins. Smoke is the general term
used for the solid and liquid matter released into the air by combustion
(pyrolysis). Exposure to fires, malfunctioning furnaces, engine exhaust,
burning food or cooking oil, self-cleaning ovens, or other sources of smoke
may induce toxicity [4,5]. Carbon monoxide, hydrogen cyanide, acidic
fumes, and particulate matter are components of smoke that cause similar
clinical signs to those seen in PTFE toxicity [9]. With smoke inhalation tox-
icity, dyspnea may not be immediately apparent. It may be several hours
before exposed birds demonstrate clinical signs. Smoke inhalation may
also lead to immunosuppression and increased susceptibility to infectious
disease [10]. In addition to oxygen and bronchodilator therapy, diuretics
may be used to treat dyspnea. The efficacy of corticosteroids in the treat-
ment of smoke inhalation is questionable. If used, the duration should be
short term, since long-term use of corticosteroids may predispose affected
individuals to secondary respiratory infections like aspergillosis [10].
Nicotine
Nicotine in tobacco smoke may be toxic. Birds most likely to be affected
are those chronically exposed, usually pets that live in smoking households
[11]. One study demonstrated that cotinine, a nicotine metabolite, was sig-
nificantly higher in the plasma of birds housed in environments with chronic
exposure to tobacco smoke than it was in controls. In humans, this metab-
olite is linked to allergies, asthma, lower respiratory illnesses, and heart dis-
ease [12]. Clinical signs in avian patients may include conjunctivitis, rhinitis,
other respiratory disease, and dermatitis [4,11,12]. Immediate treatment of
severe clinical signs is similar to that of other airborne respiratory toxicities.
Long-term treatment is managed by removing the source of smoke from the
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environment [4,5,11,12]. Second-hand cigarette smoke also releases 1,3-
Butadiene vapor, which has been shown to increase atherosclerotic plaques
in cockerels. The development of atherosclerosis may be a consideration in
birds with a history of prolonged exposure [13]. Ingestion of tobacco prod-
ucts can cause toxicity and clinical signs associated with nicotine consump-
tion, including excitability, gastrointestinal (GI) signs, neurologic signs, and
death [4,9]. Nicotine has been shown to interfere with cognitive development
in chicks when injected into eggs [14].
Miscellaneous airborne toxins
Other airborne toxins include air fresheners, hair products, nail polish,
scented candles, aerosols, gasoline fumes, glues, paints, mothballs, fumigants,
and cleaning products such as ammonia or bleach [15]. Sodium hypochlorite
(bleach) was shown to cause death within 6 to 12 days in seven birds housed in
an aviary that was cleaned with this product. Histopathologic changes in-
cluded epithelial metaplasia, hyperplasia, deciliation, and ulceration of the
trachea [16]. While all inhaled toxins have the potential to cause irritation
and damage to the respiratory tract, they may also compromise the immune
system. Inhalation of methyl chloride, a chemical compound used as a propel-
lant in aerosol products, has been shown to cause increased susceptibility to
respiratory infection in mice [17]. In one author’s practice, overheating and
melting of a plastic dish in a microwave oven caused the death of a Timneh
Gray (Psittacus erithacus timneh) within 8 hours of exposure. Histopathologic
abnormalities of the lungs were similar to those seen with PTFE toxicity.
Clinical signs and treatment of these toxicities are similar to other air-
borne toxins. In all cases of potential inhalant toxicity, birds should be re-
moved from the environment as soon as possible after exposure has
occurred and placed in a well-ventilated or oxygenated environment [5,15].
Ingested toxins
Heavy metal toxicity
The definition of a heavy metal depends on its usage. In the strict chem-
ical designation, heavy metals are defined as metals that do not normally
occur in living organisms (ie, mercury, lead, cadmium) and can cause illness.
In a medical context, the term heavy metal generally refers to any metal that
is potentially toxic. For this discussion, heavy metals will include those that
are required by living organisms in trace amounts, including iron, copper,
manganese, and zinc, but which at excessive levels can be detrimental.
This discussion does not include the radioactive heavy metals, such as ura-
nium and plutonium.
Heavy metal toxicosis is commonly seen in both pet and wild birds, with
lead (Pb) and zinc (Zn) toxicity being the most frequently diagnosed in pet
birds [4,5]. Historically, lead was the most common metal toxicity seen in pet
233PET BIRD TOXICITY AND RELATED ENVIRONMENTAL CONCERNS
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birds. However, in recent years, as lead is used less frequently in home prod-
ucts and knowledge of its toxicity in children has expanded [18], the inci-
dence of lead toxicity (also known as plumbism) in humans and other
animals has decreased [4,19].
Zinc toxicity occurs when zinc-containing items are ingested. Common
sources of avian zinc toxicity include the coating on galvanized wire cages,
galvanized toys, food and water dishes, and hardware (note: the process of
galvanization may include coating with a metal alloy that is more than 98%
zinc and can contain 1% lead). Larger birds may ingest pennies, and those
minted after 1982 have a core containing a high percentage of zinc [4,20].
Clinical signs of zinc toxicity may include lethargy, weakness, polydipsia
and polyuria, diarrhea, regurgitation (particularly passive regurgitation of
water), and less commonly neurologic signs or hemoglobinurea [4,5,15]. De-
creased fertility and sudden death were also attributed to zinc ingestion in
a group of orange-bellied parrots housed in galvanized wire caging [21].A
heterophilia and/or an anemia may be present. Radiographs may demon-
strate metal density in the GI tract, usually in the ventriculus; however, it
is possible in zinc toxicities to find no radiographic evidence of metal
[5,22]. Plasma zinc concentrations above 4 parts per million (ppm) are sug-
gestive of toxicosis. Some anecdotal reports suggest that levels as low as
2.5 ppm may be related to clinical disease. A range of 1.25 to 2.29 ppm
was found in clinically normal Hispaniolan Amazon parrots [23]. However,
birds may be clinically affected without high plasma zinc concentrations [5].
One study on the determination of diurnal fluctuations in plasma levels of
several metals, including zinc, indicated that in addition to cyclic fluctua-
tions, the established normal ranges require further study [22]. (Note,
10 mg/dL ¼0.1 ppm.) It is important that blood samples be collected in
royal blue top tubes (nonrubber) to prevent contamination of the sample
from zinc found in other rubber stoppers [4,24].
Postmortem diagnosis is best made through analysis of zinc levels in tis-
sue samples of the pancreas, liver, and kidney [25]. Kidney zinc concentra-
tions were found to be 175 ppm in a trumpeter swan (Cygnus buccinator)
that died from zinc poisoning [26]. Other histologic changes that may be
seen with zinc heavy metal toxicosis are nonspecific and include loss of
architecture and apoptosis of individual cells as well as zymogen granule de-
pletion of the pancreas [26,27], erosion of the ventriculus [26,27], and acute
tubular necrosis in the kidneys [26].
Lead
Before 1955, house paints in the United States often contained up to 50%
lead. The sweet taste of lead encourages ingestion in both children and birds.
Lead is one of the most common sources of toxicity seen in water birds and
raptors [28–30]; however, it may be seen in pet psittacines as well [4,9]. In pet
birds, sources of lead include stained glass, lead solder, curtain weights, and
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fishing sinker weights. In older houses, Venetian blinds, linoleum, and paint
may contain lead (Fig. 2A–D). During the writing of this article, toys sold at
a bird fair, marketed as bird-safe toys, were responsible for the death of one
sun conure and severe illness of another in the authors’ practice (Fig. 3A–C).
Lead solder was used to form the ‘‘feet’’ of the bathtub on this chain. Due to
the sweet smell and taste of the lead solder and the malleability of lead, the
birds ingested a significant amount of this material in the first 24 hours they
had exposure to the toy. Severe hemoglobinuria, polyuria, polydypsia, de-
pression, anorexia, and pronounced and rapidly progressive anemia were
present in both birds. Seizures occurred before death in the conure that
succumbed.
Toxicity is often associated with ingestion of lead shot or fishing weights
in water birds [29–31], and carcasses contaminated with lead shot in raptors
[28,30,32]. Clinical signs of lead poisoning are similar to those of zinc toxi-
cosis; however, clinical signs are more severe and neurologic signs are more
common with lead. In wild birds, population die-offs may occur [32,33]. One
study demonstrated that even low levels of lead (!10 mg/dL) can cause
damage to the central nervous system in chickens [18]. Teratogenesis and
embryonic death have been noted in eggs from lead toxicity [34].
Fig. 2. (A) Conure presented in cage, found moribund. (B) Close up of conure in A.(C) Lead
star that was purchased as a toy and attached to the conure’s cage. (D) Ventrodorsal (VD)
radiograph of conure demonstrating significant number of metal densities in GI tract.
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Hemaglobinuria, documented in Amazona sp, Pionus sp, Aratinga sp, Eclec-
tus sp, and African Gray parrots (Psitticus erithricus) is another clinical sign
that has been noted in psittacine birds [19]. Radiographic findings are sim-
ilar to those noted with zinc toxicosis and blood work abnormalities may
include anemia, heterophilia, and elevation of aspartate aminotransferase
(AST), lactate dehydrogenase (LDH), creatine phosphokinase (CPK), and
uric acid [4]. For determination of blood lead concentration, whole blood
may be submitted in a similar fashion as described for zinc above. Nontoxic
levels in whole blood are reported to be less than 0.02 ppm in Hispaniolan
Amazon parrots (Amazona ventralis)[23], while more than 0.2 ppm is sus-
pect and more than 0.5 ppm is diagnostic. Seven Florida sandhill cranes
(Grus canadensis pratensis) and six greater sandhill cranes (Grus canadensis
tabida) were diagnosed with lead poisoning from exposure to paint with
a high concentration of lead. Blood lead levels ranged from 146 mg/dL
(1.46 ppm) to 378 mg/dL (3.78 ppm) [35]. Lead concentrations may also
be measured in tissues, most importantly the liver where concentrations
above 6 ppm wet weight are diagnostic [9] and in bone when lead exposure
has been chronic.
Chelation therapy (Table 1) is the principal means of treatment for lead
and often for zinc toxicity. Chelating agents work by binding the heavy
metal, forming a nontoxic chelate that is excreted [36].
Fig. 3. (A) Toy sold at bird fair. (B) Closer view of same toy. (C) Close-up of miniature bathtub
on toy. Note legs of tub have been chewed.
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Ca EDTA is the chelator that has been the primary parenteral agent used
for lead (and zinc) toxicity in humans and animals. One recommended dose
in birds is 35 to 40 mg/kg intramuscularly (IM) or intravenously (IV) every
12 hours for 5 days and repeated as needed [5,37]. Another recommended
avian dosage regime is the administration of 75 mg/kg/day total dose,
divided, every 4 to 8 hours [36]. Fluid therapy should be included to prevent
possible nephrotoxicity, although this has not been documented to occur in
avian species [38]. Another form of EDTA, NaEDTA, is used for the treat-
ment of hypercalcemia. NaEDTA is stocked routinely in hospitals and its
trade name is similar to that of Ca EDTA. Inadvertent use of NaEDTA
resulted in the death of several children in 2003-2004 due to hypocalcemia,
tetany, and cardiac failure. One situation involved a naturopathic physician
who administered a compounded form of EDTA. In 2006, the Centers for
Disease Control and Prevention (CDC) recommended in its Morbidity and
Mortality Weekly Report that ‘‘Hospital pharmacies should evaluate
whether continued stocking of NaEDTA is necessary, given the established
risk for hypocalcemia, the availability of less toxic alternatives, and an
ongoing safety review by the Food and Drug Administration (FDA). Health
care providers and pharmacists should ensure that NaEDTA is not admin-
istered to children during chelation therapy.’’
Meso-dimercaptosuccinic acid (DMSA) is another chelator that may be
used. Treatment with meso-2,3-dimercaptosuccinic acid (succimer) is re-
ported to be successful in decreasing lead plasma levels and resolving
Table 1
Chelation therapy
Agent Dosage Route Indications Notes
CaEDTA 25–40 mg/kg
q 8–12 h
IM diluted Pb, Zn, Hg Most commonly used
parenteral chelator
for Pb and Zn
Penicillamine 40 mg/kg PO
q12h
PO Pb, Zn, Cu May cause
regurgitation
DMSA (meso-
dimercaptosuccinic
acid) SUCCIMER
10 mg/kg PO Pb, Hg, Cu
(may be less
effective for Zn)
Narrow margin
of safety
Desferrioxamine 20–100 mg/kg
q24h
SQ or IV Iron storage
disease
Poor GI absorption
Deferiprone 50 mg/kg
q24h
PO Iron storage
disease
Oral, but only
a partial chelator
a
Deferasirox unknown PO Iron storage
disease
Recent FDA
approval for
children with
thalassemia
Abbreviations: Cu, copper; FDA, Food and Drug Administration; GI, gastrointestinal; Hg,
mercury; IM, intramuscular; IV, intravenous; Pb, lead; PO, by mouth; q, every; SQ, subcutane-
ous; ZN, zinc.
a
Data from http://sickle.bwh.harvard.edu/chelators.html.
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clinical signs in affected birds when administered at 30 mg/kg twice a day by
mouth for 7 days with a single 50 mg/kg dose of Ca EDTA administered
initially in severe neurologic cases [39]. One study compared the efficacy
of CaEDTA and DMSA in experimentally induced lead toxicity in cocka-
tiels. Both agents were efficacious. The oral route of administration for
DMSA facilitated home treatment; however, DMSA has a narrow margin
of safety [40]. Another retrospective study of 19 birds of various species
treated with DMSA alone showed 87% decreased in serum lead concentra-
tion, and resolution of clinical signs, including neurologic abnormalities
[39].
D-penicillamine is another chelator that can be administered for heavy
metal toxicity at 55 mg/kg by mouth every 12 hours for 7 to 14 days. In chil-
dren, it is used for low to moderate levels of lead toxicity, and although
efficacious, is associated with a 33% rate of adverse reactiondmost com-
monly GI upset, rash, transient leucopenia, and thrombocytopenia [41].
In birds, GI upset is commonly reported.
Human medical studies have also shown that, when chelation therapy is
administered for lead toxicity, the concurrent administration of zinc is
beneficial [42,43]. Chelation therapy often depletes the body’s normal stores
of zinc. The administration of zinc replaces these stores, and accelerates the
chelation and excretion of lead [42,43].
Combination chelation therapy is being studied, and preliminary results
are mixed as to the advantages or these regimes [44,45].
If large metal particles are identified within the GI tract, removal is im-
portant and is accomplished by gastric lavage, endoscopic removal, retrieval
with long biopsy forceps or a magnet [25], or by surgical removal. If parti-
cles are too small to be retrieved, cathartics such as lactulose or psyllium [5]
can be administered to accelerate excretion.
Other reported avian metal toxicities include cadmium [46–48], copper
[5], mercury [49,50], and iron [51]. Except for iron, these rarely occur in
pet birds and are often a result of environmental contamination
[9,46,49,52] or food source concentration of the metal [53]. CaEDTA has
been recommended for the treatment of cadmium toxicity [36]. Mercury is
of increasing concern in wildlife that feeds from aquatic species such as
bivalves and fish, which can accumulate mercury. Mercury toxicity may
be treated with DMSA [9]. (Note: mercury found in glass thermometers is
not absorbed by the GI tract, and is therefore nontoxic.) One study demon-
strated that when chickens were poisoned with mercury, the administration
of vitamin E and selenium had a sparing effect, decreasing the incidence of
reproductive and developmental disorders [54]. Recent development of an
aminosteroidal heterocyclic compound has shown promise in preventing
the oxidative effects of iron toxicity in mammals [55]; however, its use has
not been studied in avian species.
There is evidence than some pelagic birds may be able to form stable
compounds in the liver that decrease circulating mercury [53].
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Human food
Human foods can be a source of toxins for avian pets, as owners fre-
quently share table food with their birds. Chocolate is a well-known food
toxin that causes clinical signs in many other animals as well as birds. The
toxic components of chocolate are theobromine and caffeine, both methyl-
xanthines [56]. While there is no research to demonstrate how methylxan-
thines specifically affect birds, this class of compounds has been shown in
mammals to be adenosine receptor antagonists [57]. Adenosine receptors
are found throughout the body; however, receptors in nervous and cardio-
vascular tissue seem to be most affected by methylxanthines. Antagonism
of these receptors in the cardiovascular system results in clinical signs such
as tachycardia, hypertension [56,57], and ventricular arrhythmias [56]. Aden-
osine receptors in the central nervous system (CNS) have a locomotor de-
pressant, anxiolytic, and sedative effect, thus inhibition results in CNS
stimulation, hyperactivity, and anxiousness [56–58]. Seizures and hyperalge-
sia are also possible [57,58]. Renal adenosine receptor-inhibition results in
decreased kidney function and polyuria has been noted [56,57]. Methylxan-
thines also inhibit benzodiazepine receptors and inhibit phosphodiesterase in
the CNS [56,58]. Other reported effects in mammals include increased plate-
let aggregation [57], vomiting, diarrhea, muscle tremors, hyperthermia, in-
creased respiratory rate, cyanosis, coma, and death [56]. Clinical signs may
develop in minutes to hours and may be lethal within hours of ingestion [58].
Few cases of chocolate toxicosis have been reported in birds. However,
chocolate toxicity is one of the most common poisonings reported in dogs
presented to emergency clinics. This discrepancy may be due to a combina-
tion of factors. Birds may be less likely to ingest large amounts of chocolate.
Also, birds’ relative sensitivity to chocolate has not been documented. In the
few reported cases of avian chocolate toxicosis, all resulted in death [59–61].
One patient demonstrated lethargy and mucoid feces before death [58,59],
the others were found dead. Necropsy findings in one case included hepatic,
renal, and pulmonary congestion [59]. Degeneration of hepatocytes, renal
tubular cells, and cerebrocortical cells were found in another case [59].In
one psittacine case in which the patient was found dead, chocolate was pres-
ent in the crop at necropsy and was determined to contain 250 mg/kg theo-
bromine and 20 mg/kg of caffeine [59]. The LD50 dose of theobromine and
caffeine in dogs are both reported to be 100 to 200 mg/kg. Clinical signs may
be seen in canine patients at doses as low as 20 mg/kg [56]. Before initiating
specific treatment, stabilization may be required. Seizures may be treated
with diazepam at 0.5 mg/kg IV [37]. Dyspneic patients may be placed in
oxygen [4]. Anxious or hyperactive patients may require sedation. Ventric-
ular arrhythmias may be detected on ECG, however a paper speed of
100 to 200 mm/s is required for birds and normal values have not been
established for most avian species [62]. Additionally, restraint and position-
ing for an ECG may cause excessive stress to a patient that is already
239PET BIRD TOXICITY AND RELATED ENVIRONMENTAL CONCERNS
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compromised. In canine patients, ventricular arrhythmias are treated with
beta-blockers such as metoprolol succinate or metoprolol tartrate. Propran-
olol HCl is not recommended because it slows renal clearance of methylxan-
thines. Parenteral fluid administration is recommended to diurese and clear
the methylxanthines more quickly [4].
Treatment includes removal of any remaining chocolate from the GI
tract. This is accomplished by crop and proventricular lavage, followed by
administration of activated charcoal at 1 to 3 g/kg. Both of these procedures
must be performed with care to prevent aspiration and generally require
anesthesia and tracheal intubation [4,5,9]. Emesis should generally not be
induced in avian patients because of the likelihood of resulting aspiration
[5]. Activated charcoal is sometimes administered multiple times in canine
patients because of enterohepatic recirculation [56].
Avocado
Pet birds may be exposed to toxins through ingestion of plants, some of
which may be a normal part of human diets. Avocado (Persea americana)is
known to be toxic to some avian species. All parts of the plant, including
fruit, seeds, leaves, and bark can induce signs of toxicity [5]. Not all species
of birds are equally affected by the toxins; thus, a single toxic dose cannot be
established. Avocados of several species have been shown to be lethal within
24 to 48 hours in budgerigars that were fed 1.0-mL doses of an avocado and
water mixture [63]. Larger parrots are more likely to demonstrate antemor-
tem clinical signs such as lethargy, fluffed feathers, and increased respiratory
effort [5]. The most consistent necropsy findings include pericardial effusion,
subcutaneous, edema and generalized congestion of organs, including the
lungs and liver.
P americana has been documented to cause sterile mastitis and agalactia
in cattle that ingest it, and the source of this toxicity in cattle has been
identified as a substance called persin, or (Z,Z)-1-(acetyloxy)-2-12,15-
heneicosadien-4-one. This substance has also been shown to be toxic to
mice and silk worms. At high doses (100 mg/kg) in mice it causes myocardial
necrosis and pleural effusion [64,65]. Whether the same toxin is responsible
for the toxic effects of avocados in birds has not been established.
Treatment of avian patients includes stabilization with oxygen, fluids,
and other supportive care. Removal of the toxin from the GI tract is also
important. This is accomplished by crop or proventricular lavage and
administration of activated charcoal as described above.
Onion and garlic (Allium sp) are commonly consumed in human diets, to
which pet birds may be exposed when owners share food with them. Garlic
has also been used for human nutriceutical purposes ranging from parasite
control [66] to antioxidant effects [67], which may lead owners to assume
that it is beneficial for their pet birds as well. Any plant in the Allium genus
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is capable of causing toxicity. Some common North American plants in this
genus include Allium canadensis (wild onion) and Allium validum (pacific
onion) [68]. However, house birds are likely to be exposed to species more
commonly consumed by humans such as Allium cepa (domesticated onion),
Allium porrum (leek), Allium schoenoprasum (chive), and Allium sativum (gar-
lic) [69]. All parts of the plant are toxic. Toxicity is due to sulfur-containing
alkaloids such as alkenylcysteine sulfoxide [69], diallyl sulfinate [67], and N-
propyl disulphide [66], among others. These compounds are activated by
mechanical manipulation, cutting or crushing of the plant [67,69]. They are
oxidizing agents that primarily affect hemoglobin molecules in most species
reported to be susceptible [67–70]. In dogs, cats, cattle, and goats, hemolytic
anemia results as the sulfur compounds oxidize hemoglobin and deform the
molecule resulting in Heinz body formation [68,69]. Heinz body–containing
erythrocytes become rigid, swell, and burst. They are also unable to pass
through the microvasculature of the spleen and are phagocytised [67]. While
Heinz body formation is possible in avian species, it is not a common finding
in Allium toxicity [71]. In the few case reports of Allium sp ingestion toxicosis
that have been published, birds developed anemia, anisocytosis, and an in-
creased reticulocyte count; however, Heinz bodies were rarely seen [67]. There
is not an established toxic dose in avian species; however, toxicity is seen in ca-
nine patients at 30 g/kg, and in cats at 5 g/kg [69].
Clinical signs of Allium toxicity observed in affected animals include leth-
argy, weakness, tachycardia, pale mucous membranes, collapse, and death
[67,68,70]. Clinical pathology abnormalities are consistent with intravascular
and extravascular hemolysis, including hemolytic anemia and occasional
Heinz bodies [70]. Despite the infrequent detection of Heinz bodies in avian
patients, necropsy findings in one case demonstrated that splenic erythropha-
gocytosis still occurs [67]. While icterus and increased total bilirubin are com-
mon findings in small mammals, avian species lack the enzyme biliverdin
reductase to convert biliverdin to bilirubin, and thus icterus is not frequently
seen [72]. Hemoglobin is also a nephrotoxin [67] and thus in addition to
hemoglobinurea, hemoglobinuric nephrosis may be present in avian patients
[69]. The liver may demonstrate erythrophagocytosis as well [67]. Hemosid-
erin deposition in the liver can also occur in chronically exposed animals
[67,70]. Severe liver necrosis and centrolobular vacuolization were also pres-
ent in White Chinese geese fed green onions for 3 weeks [70]. Other changes
included pericardial effusion and petechiation of the epicardium [70].
Initial treatment of onion toxicity is similar to that of other ingested
toxins, which includes initial stabilization and oxygen therapy followed by
removal of any toxin still present in the GI tract via crop and proventricular
lavage and activated charcoal administration. If anemia is severe, a blood
transfusion may be indicated [67,69]. Administration of antioxidants such
as vitamin E and ascorbic acid is recommended [67]; however, these antiox-
idants have not been shown to be beneficial in the treatment of cats with
onion toxicity [69].
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Salt toxicity is suspected in the case of a sun conure (Aratinga solstitialis)
that presented to one author’s practice. The bird was moribund after con-
suming a large number of salted mixed nuts. Notable laboratory serum
values included Na of 184 mEq/L and a chloride of 135 mEq/L.
Toxic plants
Exposure to toxic plants may also occur when a curious bird ingests
houseplants or landscaping (Table 2). There are few reports of pet bird plant
toxicosis; however, these individuals are most likely to be exposed to plants
in their immediate environment. Crown vetch (Coronilla varia) was found to
be poisonous to a budgerigar that ingested leaves from a plant next to its
cage [73]. This plant is known to be toxic in livestock that eat the plant while
foraging [68]. Toxicity is due to nitroglycoside, a chemical that may affect
the nervous system and can cause formation of methemoglobin [66,73]. An-
other group of plant neurotoxins that has been documented to affect other
animal species is grayanotoxin, which may cause clinical signs such as sei-
zures, ataxia, paralysis, or coma. Cardiac effects may also be noted [74].
Most grayanotoxin-containing plants are in the Ericaceae family, which in-
clude the commonly found Rhododendron [74].
Kalanchoe species have also been documented to cause toxicity in birds.
There are many plants in this genus, several of which are toxic. They are
commonly kept as houseplants for their colorful flowers and ease of care
[75]. One study demonstrated that several species induced clinical signs in
chickens that included ataxia, depression, muscle tremors, seizures, paraly-
sis, and death [76]. Toxic doses were reported to be 8 to 12 mg/kg [76].
Kalanchoe species have been reported to contain bufadienolide cardiac gly-
cosides [75,77]. Other plants that have been known to cause cardiac toxic-
ities include Nerium oleander (oleander), Taxus media (yew), Convallaria
majalis (lily of the valley), and Digitalis purpurea (foxgloves) [4,5,9], all of
which are commonly used in landscaping, gardens, or flower arrangements.
Cardiac signs may include increased contractility, bradycardia, wide QRS
complexes, ventricular arrhythmias, and death [74,75,78].
While there are many plants that can cause hepatic toxicosis, pet birds are
most likely to be exposed to hepatotoxic plants found around the home or
aviary. Plants containing tannic acid have been documented to cause peria-
cinar hepatic necrosis in chickens [79]. The acorns and leaves of oak trees
(Quercus spp) are known to contain tannins (tannic acid and gallic acid;
not to be confused with the tannins found in tea, which are generally benefi-
cial flavonoid precursors) and have been shown to cause toxicity in avian as
well as other species [80] when consumed [74,81]. Hepatic sinusoidal conges-
tion, diffuse heptacellular swelling, and granularity and dissociation of hepa-
tocytes were found in a double-waddled cassowary (Casuarius casuarius) that
died after ingestion of oak leaves. In addition to the liver, the kidneys and
gastrointestinal tract may be affected by oak leaf or acorn ingestion [79,81].
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Table 2
Toxic plants
Plant Toxin Systems effected Clinical signs
Coronilla varia (crown vetch) Nitroglycoside Nervous system, GI Weakness, incoordination, ataxia, collapse
Ericaceae family: Rhododendron,Pieris,
Menziesia,Leucothoe,Ledum,Kalmia
Grayanotoxins Nervous system,
cardiovascular, GI
Weakness, ataxia, paralysis, coma,
bradycardia, hypotension, other cardiac
abnormalities, mucosal irritation,
ptyalism, emesis
Kalanchoe spp, Nerium oleander (oleander),
Taxus media (yew), Convallaria majalis
(lily of the valley), Digitalis purpurea
(foxgloves), Rhododendron
Cardiac glycoside Cardiovascular nervous
system
Increased contractility, arrhythmias,
cardiac arrest, tremors, ataxia, seizures,
and coma have been reported in
Kalanchoe toxicity in chickens
Quercus sp (oak trees) Tannic acid and gallic acid Liver, kidney, lungs, GI Anorexia, polydypsia, diarrhea, weakness
Amanita muscaria (fly agaric mushroom) Amanatin Liver, kidney, GI Vomiting, hematochezia, clinical signs
associated with hypoglycemia, death
Lantana camara (Lantana) Triterpene acids (lantadene A,
lantadene B)
Liver Necrosis of nonpigmented/unfeathered
skin exposed to UV light
Lilium spp (Asiatic, Easter, tiger, and
star-gazer lilies)
Unknown Kidney Signs of acute renal failure, toxicity only
documented in domestic cats
Rheum spp (Rhubarb) Oxalate crystals Kidney, GI Vomiting, swelling/edema of oral mucous
membranes, clinical signs consistent
with acute renal failure
Schefflera (umbrella plant), Spathephyllum
(peace lily), Dieffenbachia (dumb cane),
Epiprenum (pothos), Philodendron spp
Oxalate crystals GI, serum calcium, kidney Regurgitation, ptyalism, oral mucosa
and choanal edema
This list of toxic plants represents plants that are commonly found in and around a home environment or have specifically been shown to be toxic to birds.
There are many other plants considered to be toxic that are not listed here and this list should not be considered all inclusive.
Abbreviation: GI, gastrointestinal tract.
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Amanita muscaria or the fly agaric mushroom [82] produces the well-
known hepatotoxins, amantins. These toxins inhibit RNA polymerase and
result in cell death. These mushrooms are found in almost every geographic
region and primarily grow in association with birch, pine, spruce, fir, and
larch trees [82]. Clinical signs are divided into four stages in people [83]
and this course may be followed in other species, or ingestion may be rapidly
fatal [84,85]. The initial stage is a latency period of 8 to 12 hours in most
affected mammals. This is followed by severe gastrointestinal signs: vomit-
ing, bloody diarrhea, and severe abdominal pain. Generally, a lag period
follows that can vary from several hours to several days, depending on
the dose and the individual’s sensitivity, when the patient appears to have
recovered. During this time the amantins are preferentially causing the
greatest cell death in tissues with the highest metabolic rate: the hepatocytes
and proximal tubules of the kidney. Massive hepatic glycogen breakdown
may cause death due to hypoglycemia. This is followed by hepatic and renal
failure, and necropsy findings may often demonstrate panlobular coagula-
tive necrosis of hepatocytes [83]. Liver tissue samples may be tested
for amanitin by mass spectrometry or liquid chromatography to confirm
diagnosis [86].
Although a food source for some indigenous species, such as Gopher
tortoises (Gopherus polyphemus), Lantana camara may cause hepatotoxicity
in avian and other species [68,87,88]. This plant is found in tropical areas of
North America and is commonly used in landscaping and grows wild in
many southern US states [88]. Photosensitization and resulting necrosis of
unfeathered skin was observed in a group of ostriches that consumed hay
contaminated with lantana [87]. Photosensitization and hepatotoxicity are
well-documented phenomena in livestock consuming lantana; however,
not all species are toxic and a large amount must be consumed to induce
toxicity in cattle. Hepatic damage caused by Lantana spp impairs the liver’s
ability to breakdown phylloerythrin, a chlorophyll by-product that is
removed from circulation in a normally functioning liver. This compound
is photoreactive and when high levels are present in circulation it is respon-
sible for the observed necrosis of unpigmented skin exposed to UV light [68].
Kidneys may also be affected by toxic plants. Plants in the Lilium genus,
such as the following lilies: Asiatic, Easter, tiger, and star-gazer, have been
well-documented to cause acute renal failure in cats [89]. The toxic compo-
nent(s), mechanism of toxicity, and pathogenesis have not been determined
[89] and there are no reports of Lilium renal toxicosis in avian patients. As
mentioned earlier, plants containing tannic acid may cause renal damage
[79,81]. Rhubarb, a plant commonly grown in gardens may be nephrotoxic
[5]. Toxicity is due to oxalate crystals, which are found in high concentra-
tions in rhubarb leaves. Consumption of leaves may result in oxalate
nephrosis [68]. Other plants containing high levels of oxalate crystals,
such as beetroot and spinach may also result in renal failure [90]. However,
renal toxicity varies with the species that ingests the oxalate-containing
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plant, the pH of the stomach, and the bacterial population of the GI tract,
all of which may influence the solubility and absorption of oxalate
[83,90,91].
Many plants responsible for other organ toxicities may cause GI signs as
well. Oxalate crystal–containing plants are irritants to the GI tract [5]. Crys-
tals cause pain, inflammation, and edema of the oropharyngeal mucosa on
contact. Ptylism, dysphagia, and regurgitation may also be seen [4,74,77].
Soluble oxalate crystals may bind calcium and magnesium after absorption
from the GI tract. Livestock that consume large quantities of oxalate-con-
taining plants may develop hypocalcemia and hypomagnesaemia and die.
Renal tubular damage may also occur [68]. Pet birds are unlikely to con-
sume large volumes because of the pain associated with ingestion [74]. Com-
mon houseplants that contain oxalates include Schefflera (umbrella plant),
Spathephyllum (peace lily), Dieffenbachia (dumb cane), Epiprenum (pothos),
Philodendron, and others [4,9,68,74,77]. A commonly seen presentation is
the ingestion of a small amount of pothos or philodendron houseplant.
This has been noted most commonly by one author in cockatiels, which
present with sudden onset of fluffing, pytalism, head shaking and ‘‘flinging’’
oral mucous. The tongue and choana are often erythematous. Symptomatic
and supportive care has resulted in recovery in all cases to date, but more
aggressive therapy may be warranted.
Other plants that have been shown to induce toxicity in birds and that
may cause GI signs include Robina pseudoacacia (black locust), Euphorbia
pulcherima (poinsettia), Parthenocissus quinquefolio (Virginia creeper), and
Montana rubens (clematis) [9].
In any plant toxicity, after initial stabilization, removal of any remaining
plant from the GI tract is indicated and is accomplished through crop and
GI lavage. Activated charcoal is also effective in most plant intoxications,
neutralizing toxic components remaining in the GI tract. Further treatment
is directed at the organ systems affected and clinical signs.
Mycotoxins
Mycotoxins are toxins produced by fungi and commonly occur in fungal-
contaminated grain products [9,92]. A commercial dog food with a high
aflatoxin level was responsible for the acute deaths of 23 dogs in the United
States in 2005. Avian species are more susceptible than other affected spe-
cies, such as dogs, cattle, swine, and humans, to aflatoxicosis [93]. Aflatoxin
and fusariotoxin are often responsible for avian mycotoxicosis and are
usually associated with cereal grains, corn, and peanuts that have been
exposed to or kept in humid, moist conditions [92].Aspergillus flavus pro-
duces aflatoxins and Fusarium produces fusariotoxins [92,94]. Clinical signs
of chronic aflalotoxicosis often include lethargy, weight loss, anorexia,
regurgitation, and polydipsia [92,94]. The CNS may also be affected in
some species [95] and signs such as ataxia may be noted [92]. Mycotoxins
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are hepatotoxic and histologic changes include increased content of hepatic
glycogen, portal infiltrate of monocytes, increased lipid droplet accumula-
tion, hepatic necrosis and bile duct hyperplasia [92,96]. Changes in levels
of specific neurotransmitters in the pons and brain stem have also been
noted in some species [95]. Testing for mycotoxins in food and in the patient
can be difficult because of variation in toxic concentration and the inconsis-
tent production of toxins [9].
While there is no specific treatment for mycotoxicosis, birds that are at
high risk of exposure may benefit from supplementation with glucomannans
and organic selenium, which appear to decrease the hepatotoxic and CNS
changes associated with exposure [96,97]. While domestic animal feeds are
required to contain less than 100 ppb of mycotoxins, hepatic changes
have been shown to occur in turkeys at levels as low as 100 to 400 ppb
[98]. In the United States, the acceptable level of total aflatoxins in food
for human consumption is less than 20 mg/kg, except for Aflatoxin M1 in
milk, which should be less than 0.5 mg/kg. The official document can be
found at the Food and Drug Administration’s (FDA) Web site: www.fda.
gov. Other animal species have been documented to suffer from toxicity
caused by various mycotoxins such as Penitrem A and roquefortine, both
tremorgenic toxins, after consuming moldy human food [99]. The best
way to protect pet birds from exposure to mycotoxins is to feed only
human-grade grain, corn, and peanut products; avoid spoiled foods; and
store grain products in cool, dry places.
Oil
Much is known and is still being studied regarding the adverse effect of
crude oil on sea and coastal birds. Major oil spills over the past half-century
have unfortunately given us a plethora of opportunities for research. Al-
though the marine oil spills are the most notorious, the most oil contamina-
tion of the environment comes from land-based activity. The lighter
fractions of oil, such as benzene and toluene, are more toxic, but are
more volatile and evaporate quickly. Heavier components of crude oil,
such as polynuclear aromatic hydrocarbons (PAHs), may cause the most
extensive adverse effects; while they are less toxic, they persist in the environ-
ment much longer than volatile components. The initial effects on seabirds
include damaging the feathers’ ability to insult and to allow flight. Ingestion
of oil via preening causes GI irritation, GI ulceration, and hemolytic anemia
[100]. Dehydration and emaciation are commonly seen in birds that are
victims of oil spills. Recent research has demonstrated that long-term effects
include greatly decreased acetylcholinesterase brain activity in some species
[101].
While exposure to oil is more common in free-ranging birds, pet birds may
be exposed under various circumstances. Exposure to cooking oil is usually
the result of a pet bird flying into a cooking pan on the stove or left out in the
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kitchen. They may also be intoxicated through exposure to petroleum-based
products [9]. While hot oil can result in severe burns (a common pet bird
emergency presentation), the oil itself inhibits feather function and is ingested
as the bird preens [9,100,102]. Ingestion of oil products may have several sys-
temic effects. Diarrhea and dehydration are the most frequently noted clini-
cal signs [9]. Ingestion of crude oil by marine birds has been reported to cause
GI hemorrhage and liver and kidney dysfunction [100]. Crude oil has also
been shown to cause hemolytic anemia in several avian species [102]. Oil in-
gestion may also result in immunosuppression and secondary fungal and
bacterial infections [103]. Pneumonia is also seen when oil is aspirated [9].
Treatment includes removal of oil from feathers using a dilute dishwashing
detergent and hot water (106F) [102]. This may need to be repeated several
times. Washing should not be attempted until the bird is stable. Recently,
dry-cleaning techniques with the use of iron powder and magnetic removal
have been studied for their value as a less stressful and more effective method
of oil decontamination [104]; however, one must take into consideration the
potential risk of toxicity from oral exposure to iron. Further treatment in-
cludes supportive care based on clinical signs including oxygen therapy, fluid
therapy, antibiotic therapy, antifungal therapy, liver protectants, pain man-
agement, and nutritional support.
Pesticides
Pesticides are commonly encountered in the free-ranging avian patient;
however, pet birds may be exposed to pesticides used in a home setting.
The most common types of pesticides include organophosphates, carba-
mates, and pyrethrins [9,105]. Exposure may occur by inhalation or inges-
tion [9]. Organophosphates and carbamates are anticholinesterases and
work by inhibiting cholinesterase [106]. Without cholinesterase to bind ace-
tylcholine at the neuromuscular junctions, excessive acetylcholine leads to
paralysis, which can eventually involve the muscles of respiration [107].
Clinical signs include weakness, lethargy, ataxia, tremors, seizures, and
death [107]. Pupillary miosis, which is often noted in mammals with anticho-
linesterase toxicity, will not be seen in birds because of the striated muscle of
the iris. Diarrhea and ptyalism have also been reported in association with
exposure to organophosphates and carbamates in avian patients [108,109].
Thriam and other multiple sulfide group–containing carbamate pesticides
have been shown to cause tibial dyschondroplasia and lower body weight
in young growing broiler chickens and turkeys fed at high doses of
50 mg/kg and 400 mg/kg, respectively [110,111]. Reproductive effects have
also been noted [107]. Diagnosis is made by history of exposure, identifica-
tion of consistent clinical signs, and demonstration of reduced cholinesterase
levels in brain tissue or serum [107,110].
Treatment consists of the administration of anticholinergics such as
atropine, with suggested doses ranging from 0.01 to 0.1 mg/kg
247PET BIRD TOXICITY AND RELATED ENVIRONMENTAL CONCERNS
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subcutaneously (SQ), IM, or IV [37,108,112]. However, in mammals, organ-
ophosphate-induced signs usually do not respond to the lower end of the
dose range [9,112]. Pralidoxime chloride (2PAM) is used as an antidote
for organophosphate toxicity in dogs and cats, but is not recommended
for treatment of carbamate toxicity [112].
Pyretherins work by gate alteration of sodium, calcium, and chloride
channels [113]. Clinical signs of pyretherin toxicity in mammals include
behavior change, tremors, hyperthermia, and seizures [112,113]. Pyretherins
may also impair the immune system and alter numerous metabolic pathways
in birds [114]. Pyrethrin toxicity often occurs in cats when high concentra-
tion (45% to 50%) canine spot-on pyrethrins are applied [112]. Diagnosis
is made by recognition of clinical signs and history of exposure. Diazepam
may be administered for treatment of seizures; however, it has been shown
to be only partially effective in pyretherin toxicity [112,113]. Methocarbamol
has been used in mammals to control tremors. If topical exposure has oc-
curred, once a bird is stable, bathing in dilute dish soap is indicated to re-
move any residual toxin [112].
Wild bird toxicity still occurs from the metabolites of banned pesticides,
such as DDT. In 1999, Lake Apopka, Florida, was the site of a major die-off
of white pelicans (Pelecanus erythrorhynchos), wood storks (Mycteria amer-
icana), great blue herons (Ardea herodias), and great egrets (Casmerodius
albus). This was caused by flooding of farmland to provide replacement
wet lands for the areas lost to extensive development. Unfortunately,
although spot testing of the soil was performed, a high concentration of
organochlorines, especially toxaphene, were released into the water of the
newly formed wet lands, having been exuded from the underlying soil.
Over 800 birds are known to have died in this incident, and the effect on
propagation is still not known because of the migratory nature of several
species, including the white pelican. Potential delayed effects of these
organochlorines (OC) may include; thin-shelled eggs, decreased sperm pro-
duction, cessation of egg laying, and decreased hatching rate. The reproduc-
tive effects of OCs seem to be more pronounced in avian species than in
mammals. Another potential sequelae to OC toxicity is osteodystrophy,
which can be manifested by pathology in numerous bones. Carcinogenesis
has been widely theorized but not proven [115].
Rodenticides
Pet birds may also be exposed to rodenticides in the home environment;
however, most cases of rodenticide poisoning in birds occur in wild raptors
and other birds that are nontarget species [116]. Anticoagulent rodenticides
work by inhibition of the extrinsic, vitamin K–dependant pathway, in partic-
ular factor VII. Because birds rely more on the intrinsic pathway, factor VII
may play a less important role in avian species and thus explain their appar-
ent decreased sensitivity to anticoagulant rodenticides [117]. However, cases
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of toxicity have been documented in raptors and other free-ranging birds.
Sensitivity to rodenticide appears to vary among avian species, with docu-
mented brodifacoum (second-generation rodenticide) toxicity occurring at
doses less than 1 mg/kg in some species and greater than 20 mg/kg in other
species [116]. Clinical signs are similar to those seen in other animals and in-
clude hemorrhage, hematochezia, bruising, petechiation, and death [9,116].
While tests to assess function of clotting factors V, VII, and X have been
developed in chickens, they are species-specific and have not been tested in
other avian species [118]; thus, clotting factor function cannot be routinely
evaluated in avian patients at this time.
Treatment is similar to that in mammals and consists of vitamin K sup-
plementation. Treatment should be continued for 14 to 28 days [37].
Hypercalcemic rodenticides have been reported to cause death in birds
[119]. These rodenticides are calciferol derivatives and produce hypercalce-
mia. The hypercalcemia leads to increased ionized calcium levels, metastatic
calcification, cardiac conduction disturbances, renal failure, and death.
Some rodenticides are a combination of anticoagulant and calciferol, with
these two agents producing a synergistic effect.
Clinical signs of exposure to hypercalcemic rodenticides vary widely.
Therefore, in addition to a markedly elevated serum calcium, a history of
potential exposure is needed for diagnosis, and other causes of hypercalce-
mia must be ruled out (including paraneoplastic disease, lymphoma, hyper-
parathyroidism and, in birds, estrogen-related normal reproductive
hypercalcemia).
Treatment of rodenticide hypercalcemia includes intense diuresis, gluco-
corticoids, and an antihypercalcemic. Pamidronate, a bisphosphonate, acts
to inhibit bone resorbtion. This drug was designed for the hypercalcemia of
malignancy in humans, and is preferred over calcitonin for treatment of
rodenticide hypercalcemia.
Zinc phosphide is commonly used as a rodenticide on golf courses, high-
ways, and other large areas where rodent control is required. It may be for-
mulated as a grain-based bait or as a paste. Symptoms of acute zinc
phosphide poisoning may include vomiting, diarrhea, cyanosis, low blood
pressure, and loss of consciousness [120]. Zinc phosphide releases phosphine
gas in the acid environment of the stomach. This gas is responsible for the
toxic effects. Zinc phosphide has a strong, pungent odor that does not deter
rodents, but which is offensive to many mammals. However, birds, notably
wild turkeys, are not deterred by the odor. Of the avian species studied, the
most sensitive to zinc phosphide toxicity are geese, pheasants, morning
doves, quail, and mallard ducks [120].
There is no specific antidote for zinc phosphide toxicity. Supportive care
includes gastric lavage to remove as much of the material as possible, fol-
lowed by sodium bicarbonate to decrease the release of any addition phos-
phine gas. Calcium gluconate and sodium lactate may be administered IV to
counteract systemic acidosis.
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At the time of this writing, bromethalin is the most commonly sold over-
the-counter rat and mouse bait. Bromethalin is a rodenticide that causes
cerebral edema. Paralysis, seizures, and death ensue in the target species
within 24 to 36 hrs. There is no specific test for this agent, nor is there an
antidote; therefore, the primary treatment is the rapid induction of emesis.
Although there is a risk of aspiration when emesis is induced in birds, if
gastric lavage cannot be accomplished promptly and thoroughly, inducing
emesis may be considered. Additional treatment involves the administration
of activated charcoal and supportive care.
Although the LD
50
in birds is not known, extrapolating from the dog
(4.7 mg/kg) and cat (1.8 mg/kg) will assist the practitioner is assessing the
degree of avian exposure to bromethalin [117].
Ethylene glycol
While uncommon, there have been reports of and research done that
demonstrate avian susceptibility to renal failure induced by ethylene glycol
ingestion [121]. Clinical signs include lethargy, ataxia, incoordination, and
death [122]. Clinical pathology may demonstrate a metabolic acidosis and
in mammals low blood calcium may be seen due to the formation of calcium
oxalate crystals. Histopathologic findings include hepatocyte and renal
tubular necrosis and degeneration with calcium oxalate crystals visualized
in the tubules. Grossly, the kidneys and liver may be congested and enlarged
[121]. Treatment in mammals includes fluid diuresis and the administration
of ethanol or fomipizol. Prognosis varies depending on the amount ingested
and the time elapsed from ingestion to treatment.
Iatrogenic toxicities
Any drug, medication, or supplement can be toxic at high enough doses.
Avian patients may be more likely to suffer from iatrogenic toxicities
because of their small size and resulting dosing mistakes. Many drugs that
are commonly used in other species are not approved or studied in avian
species and thus therapeutic and toxic doses are unknown. Recently, a study
demonstrated that passerines and Columbiformes are sensitive to fenbenda-
zole and albendazole [123]. Anecdotal reports of toxicity in cockatiels fol-
lowing repeated fenbendazole administration have been frequently
reported [124]. A group of kiwi demonstrated acute respiratory distress
and death after administration of levamisole at recommended doses of
25 to 43 mg/kg [125]. Furthermore, medications in aviary situations may
be administered in food or water, which does not allow control over individ-
ual dosages.
Consumption of owners’ medications by pet birds may be encountered.
Birds that are prone to chew, because of age, species, or individual temper-
ament, are more likely to be affected. The amount of a substance ingested
is often difficult to determine. Knowledge of the clinical signs of overdose
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for a given drug in other species can be extrapolated to birds. The bird
should be observed for the occurrence of any clinical signs that warrant
treatment.
Vitamins and minerals
Toxicity may occur from over supplementation of vitamins and minerals.
Fat-soluble vitamins, such as vitamin A and D, are more likely to cause tox-
icity when overdosed. Supplementation with these should be avoided when
a balanced, pelleted diet is fed [126].
Vitamin D
Necropsy findings in chronic excessive vitamin D3 ingestion include soft
tissue calcification and renal failure, and chronic vitamin D excess may con-
tribute to atherosclerosis in mammals and birds [77,127,128]. Cholecalcif-
erol should be used when oral vitamin D3 supplementation is necessary.
Since cholecalciferol must be metabolized via the liver and kidney before
activation, toxicity is unlikely. Vitamin D3 toxicity has been induced in ma-
caws at lower dietary levels than in other species (1000I U/kg). This suggests
that vitamin D3 metabolism varies among psittacine species. Poultry fed
excessive vitamin D3 use the egg as an excretion vehicle, leading to embry-
onic death; a mechanism not available to most pet bird species. Pending
further research, it seems prudent to feed parrots a formulated diet contain-
ing vitamin D3 at concentrations at or slightly below the poultry require-
ments. In addition to the provision of adequate dietary calcium and UVB
light, this should to prevent metabolic bone disease and potential vitamin
D3 toxicity problems.
Vitamin A
Although vitamin A deficiency is a common problem in pet birds, and
studies to determine minimum requirements for health and breeding are
ongoing [77,129], vitamin A toxicosis has been reported to cause both repro-
ductive disease, osteodystrophy, and other behavioral and metabolic abnor-
malities in several species of birds [130].
In addition to altering the diet to decrease vitamin A content, administra-
tion of vitamin E has been shown to decrease serum vitamin A levels in rab-
bits [131]. When needed, supplementation of vitamin A should be in the form
of beta-carotene, which is less likely to cause toxicity [77]. The vitamin A con-
tent of hand-rearing formulas, nectars, and pellets, should be evaluated. No
recommendation can yet be made as to minimum or maximum dietary levels
of vitamin A, but cockatiels fed 10,000 IU/kg as adults developed clinical
signs of vitamin A toxicity. Many commercial products exceed this level [5].
Mineral toxicity is also possible with supplementation and potentially
toxic minerals include selenium [132,133].
251PET BIRD TOXICITY AND RELATED ENVIRONMENTAL CONCERNS
Author's personal copy
Iron
Soft-billed birds, such as the Rhamphastos (toucan) family, Fracula reli-
giosa (Indian Hill Mynas), hornbills, starlings, and birds of paradise have
been shown to be very sensitive to dietary levels of iron and commonly de-
velop iron toxicosis [77,134–138]. In mynah birds, it has been demonstrated
that excessive iron absorption from the GI tract is at least in part
accountable for the prevalence of iron storage disease in captivity. When
compared with chickens, mynah bird enterocytes have a significantly higher
limiting uptake rate for iron, possibly because of an increased number of
transporters [139]. In toucans, it has been demonstrated that lower-iron
diets can successfully decrease hepatic iron content [140]. Although the exact
mechanisms by which each susceptible avian species develops iron storage
disease is not known, increased iron absorption and captive diets with
higher iron content than is found in their natural diets, are likely factors.
In some species, the wild diets may contain high levels of tannin-containing
plant material, which inhibits iron absorption [134]. Tannins (not the same
as tannic acid that occurs in other plants) are the precursors of flavonoids or
catechins, which have been reported to possess divalent metal chelating,
antioxidant, and anti-inflammatory activities; to penetrate the brain barrier;
and to protect neuronal death in a wide array of cellular and animal models
of neurologic diseases [141]. Current recommendations for diets of suscepti-
ble species should have maximum iron levels of 20 to 40 ppm [136].
Lories (Family Loriinae) have also been documented to have a dispropor-
tionate incidence of iron storage disease, although it is unclear whether this
is due to unusually high dietary iron, other nutritional factors such as excess
dietary vitamin C or A, or a species predilection [77,142,143].
Clinical signs of iron toxicosis/iron storage disease may include poor
plumage, anorexia, lethargy, weight loss, ascites, dyspnea, and death. Ele-
vated liver enzymes and/or elevated bile acids may be noted [136]. In clini-
cally affected birds, an elevated PCV has been reported, but a causal
relationship has not been documented (B. Speer, personal communication,
November 2007). Serum iron levels may not be diagnostic and liver biopsy
has the highest diagnostic yield [136]. Pathologic changes include accumula-
tion of iron in the liver and iron deposition may also be noted in splenic, pan-
creatic, pulmonary, and renal tissues [136]. A precursor of iron storage
disease is hemosiderosis, defined as the presence of excessive iron in the liver
without alteration of tissue morphology. Iron storage disease, often referred
to as hemochromatosis, is histologically distinguishable from hemosiderosis
and involves hepatocellular damage. The term hemochromatosis has become
synonymous with hereditary iron overload syndrome in people. Although
the exact mechanism in people by which excessive iron is accumulated is
unknown, human hemochromatosis is one of the most prevalent heritable
genetic diseases and is caused by one of several gene mutations. To avoid
confusion with the syndrome in people, in which the cause is known to be
252 LIGHTFOOT & YEAGER
Author's personal copy
genetic and associated organ involvement may differ from that seen in birds,
the term iron storage disease is currently preferred in avian medicine.
Treatment consists of repeated phlebotomies, use of iron chelators such
as deferiprone or deferoxamine mesilate (see Fig. 1)[136], restricting vitamin
A and C intake and a low-iron diet [77].
Summary
Birds may be exposed to toxins through a variety of sources in their every-
day environment. Toxicity may occur through inhalation or oral or dermal
exposures. It is the clinician’s responsibility to diagnose and treat these tox-
icities to the best of his or her ability in an effort to correct the disease of the
individual patient. Recognition of toxicity in the avian patient has further
significance as it relates to the patient’s environment, including the health
of other animals, humans, and the ecosystem. Veterinarians diagnosing poi-
soning in animals have a responsibility to consider human health implica-
tions as well as treating their patient(s). While some toxicities, such as lead
and zinc toxicosis, are well documented in avian species, others are limited
to anecdotal reports and extrapolation from other species. Continued
research is needed in this area of avian medicine to expand our knowledge
and improve our ability to diagnose and treat toxic conditions in birds.
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PET BIRD TOXICITY AND RELATED ENVIRONMENTAL CONCERNS
... The chelate formed is nontoxic and can be excreted in the urine initially at up to 50 times the normal rate. The chelating agents used for the treatment of lead poisoning are edetate disodium calcium (CaNa2 EDTA), dimercaprol (BAL) which is injected and succimer and d-penicillamine which are administered orally (Lightfoot et al., 2008). To reduce lead poisoning is to prevent exposure to lead. ...
... Recommended steps to reduce blood lead levels in adults and children include increasing frequently hand washing, increase intake of calcium and iron, eliminating lead containing objects like blinds and jewelry in the house. In houses with lead pipes or plumbing solder, run water in the morning to flush out the most contaminated water and to prevent corrosion of pipes (Lightfoot et al., 2008;Robert et al., 2000;Rooney, 2007;Rossi, 2008;Routledge & Steve, 1998). Lead testing kits should be provided in the house to screen and test the blood of children for exposure. ...
... The susceptibility to cadmium can vary greatly between aquatic organisms. When cadmium is transported over a great distance, it is absorbed by sludge and cadmium rich sludge can pollute surface water as well as soil (Lane et al., 2005;Lightfoot & Yeager, 2008;Zarel et al., 2003Zarel et al., -2007. Cadmium can be detected when about 10 milligrams of cadmium contents has been absorbed either through the skin, inhalation or ingestion. ...
Research
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Extant studies have revealed that water and soil pollution are among the major global challenges that society must address in the 21st century aiming to improve water quality and reduce human and ecosystem health impacts. Industrialization, climate change, and expansion of urban areas produce a variety of water and soil contamination. In this study, the authors discussed some of the relevant findings in extant literature related to the release of heavy metals into water and soil content, that is affecting agricultural practices, and hence, serve as possible risks for human health. Thus, the aim of this study is to review previous research work done by other authors on heavy metals in water and soils, detection, poisoning, damages to human health and treatments of agricultural soils as noted in some studies. The study adopts an extensive review of literature such as conference papers, journal articles, internet sources, books to find out concentration of heavy metals in agricultural soils and water. After analysis and review of such secondary articles, the current studies found that heavy metal in portable water and soil is a source of major concern and should be regularly checked and monitored by appropriate regulatory agencies. In addition, some previous researchers found that anthropogenic activities are identified as the main source of the increasing amounts of heavy metals found in water and soil. Some of the health hazards derived from repeated exposure to traces of heavy metals, including lead, cadmium, nickel, and zinc, were also reported in this study. The authors also stated the methods in which this contamination occurs and ways to prevent future contamination as discussed by various authors. This study concluded that heavy metals are the main cause of water pollution and impact human health worldwide. Keywords: Heavy Metal: Water: Contamination: Pollution: Human Health: Anthropogenic Factors: Nigeria.
... 6 Birds are not usually keen to ingest large amounts of chocolate. 7 Chocolate also contains theobromine as another potentially toxic substance and therefore these reports are not conclusive about caffeine intoxication. On the other hand, extrapolating the knowledge on caffeine toxicity in humans and/or dogs to avian species does not seem plausible due to considerable anatomical and physiological differences that may affect toxicokinetic and even toxicodynamic profile of the toxicant and subsequently patient's response and outcome. ...
... We could not evaluate cardiovascular signs in pigeons due to the fact that birds were severely over-reactive and the process could lead to more stress. 7 As previously stated, clinical signs of intoxication had a fast onset. This can be related to fast absorption of caffeine especially in starved birds. ...
Article
Full-text available
Limited knowledge is available on acute intoxication with environmental toxicants in birds. This experimental study determines features of acute caffeine intoxication and clinical outcome of different treatments in pigeons. The experiment was performed in three phases. Toxicity tests were performed in phases one and two while phase three was dedicated to comparative evaluation of fluid therapy and activated charcoal with or without diazepam and/or propranolol on clinical outcome of birds. Calculated LD50 was 366 mg kg-1 although presence of regurgitation compromised the accuracy of LD50 application. The dose-response (death) curve was sharp with a slope of 8.41. Clinical signs included renal, neurological, gastrointestinal and respiratory symptoms that generally initiated in a few minutes and lasted for few hours. The approximate toxic dose (ATD) was 294 mg kg-1. Serum and brain concentrations after administration of ATD followed a normal distribution in a range of 14.6 - 83.3 mg mL-1 and 1.04 - 7.81 µg g-1, respectively. Fluid therapy and activated charcoal with or without propranolol did not affect the clinical outcome of intoxicated birds while adding diazepam and intensive therapy with all of these agents even worsened the situation. In conclusion, caffeine is a potential source of intoxication in pigeons with a fast onset of clinical signs and a sharp increase in death rates by increasing doses. Symptoms are similar to mammals with prominent neurological signs although the ATD and serum concentrations are relatively high. Intensive therapy with above mentioned drugs is not recommended. Most birds survive after resolution of transient clinical signs without any special treatment.
... For most pet bird species, a balanced pelleted diet should make up the majority of their diet, and supplemental foodstuffs appropriate for the species should also be provided. Commonly encountered toxic foods in birds include avocado, chocolate, and Allium plant species like garlic and onion [6]. While beyond the scope of this chapter, there are many excellent resources for proper pet bird nutrition available to the clinician [2,7]. ...
... Undigested seed or other food material in the droppings indicates an abnormality within the gastrointestinal system. Hemoglobinuria or porphyrinuria may occur secondary to heavy metal toxicosis [6]; this may manifest as chocolate colored or blood tinged stools in some parrot species. Dark-colored feces may be indicative of melena or a diet containing highly pigmented berries or fruits. ...
Chapter
In exotic animal emergencies, collecting a thorough, yet focused history allows for expert care of the patient by focusing diagnostic and treatment decisions. Husbandry plays a pivotal role in pet bird health, and gathering specific information on housing, diet, and other elements of a patient's care can help discover underlying medical issues. The clinical examination is further divided into visual and physical exams. A comprehensive, systematic examination often reveals subtle abnormalities and helps to determine the extent or source of a patient's illness. This chapter discusses how to collect a detailed medical history on the emergent avian patient and also provides the clinician with a guide to performing an avian physical examination, with tips for different popular pet bird species.
... This work, however, is the first to analyze samples of bioprocessed and non-bioprocessed coffees from the same farmer (same harvest location and cultivar), which strengthens the relevance of this finding. Since caffeine is recognized as toxic for avians (Lightfoot and Yeager, 2008), it was probably not absorbed in the digestive tract of the Jacu bird. Baumann et al. (1995) reported that under simulated gastric conditions, caffeine was not released from guaraná (Paullinia cupana) seeds. ...
Article
Full-text available
Exotic coffees may be defined as extravagant and unique coffees, primarily due to their production mode, including unusual bioprocessing or fermentation conditions associated with superior sensorial characteristics. The aim of the present study was to investigate the influence of bioprocessing and of growing conditions on flavor precursors of Jacu and Kopi Luwak exotic green coffees, respectively. Moreover, this is the first study to perform a detailed chemical analysis of these exotic coffees. Thirteen green Coffea arabica bean samples were obtained, five from Espírito Santo state, Brazil, and eight Kopi Luwak from different regions of Indonesia. Samples were analyzed regarding their proximate composition, chlorogenic acids (CGA), sucrose, alkaloids, triacylglycerols (TAG), diacylglycerols, free fatty acids, sterols, diterpenes and tocopherols. Scanning electron micrography confirmed bioprocessing of Jacu and Kopi Luwak coffee samples. Bioprocessing by the Jacu bird caused reductions of 69 and 28% in caffeine and CGA contents, respectively. The TAG profile of Jacu coffee was modified. TAG containing two saturated fatty acids were preferably hydrolyzed in detriment to those containing two unsaturated fatty acids. Other coffee components were not affected by the bird's digestion of the beans. Kopi Luwak coffee samples had a chemical composition in accordance with reported ranges for non-bioprocessed green C. arabica samples, except for caffeine (0.48 g/100 g) and CGA (5.09 g/100 g), which were found in low amounts. Crop year rather than location or post-harvest processing discriminated Kopi Luwak coffee samples, suggesting that weather conditions would be the most crucial aspect for their chemical composition, especially in terms of total lipids, ashes, total CGA, sucrose and proteins.
... The ingested lead is conjugated in the liver and passed to the kidney, where a little amount is discharged and the rest accumulates in different body organs, influencing numerous biological activities at the molecular, cellular, and intercellular levels, which may induce morphological changes that can stay even after lead levels have fallen (Flora et al. 2006). The pollution of soil, water, air, and food by dispensable materials of plants such as batteries, paints, and leaded fuel is the primary cause of lead poisoning (Lightfoot and Yeager 2008;Ferreyra et al. 2009). Water is a significant hotspot for lead poisoning because of the leakage of lead from water pipes (Campbell et al. 2000). ...
Article
Full-text available
This study assessed prophylactic potentials of silymarin against lead-induced hepatorenal toxicity in rats with the respect to its antioxidant and anti-apoptotic activities. Forty male albino rats were distributed into four groups. Control group is provided with distilled water. Lead acetate group was given lead acetate (100 mg/kg bwt) orally for 10 weeks. The third and fourth groups administered silymarin at doses of 50 or 100 mg/kg bwt, respectively, 1 h before administration of lead acetate for 10 weeks. Lead acetate altered liver structure and function that represented by significant elevation of the activities of serum aspartate and alanine aminotransferases and serum levels of urea and creatinine. Hepatic and renal tissues’ malondialdehyde concentrations were increased, while reduced glutathione content and superoxide dismutase and catalase activities were reduced in the lead acetate group. Also, lead acetate increased caspase-3 mRNA expression and inhibited alpha-fetoprotein mRNA expression in hepatic tissues, as well as it altered liver and kidney tissues’ architectures. In contrast, silymarin ameliorated in a dose dependent mannar the toxic effects of lead acetate on the liver and kidneys through modulation of lead acetate which altered liver and kidney function and structures via reducing lipid oxidation and pathological changes of hepatic and renal tissue structure, improving antioxidant defense system of liver and kidneys, and decreasing pro-apoptotic gene expression in hepatic tissue. This study indicated that silymarin ameliorated lead acetate-induced hepatorenal toxicity via its antioxidant and cytoprotective potentials. Graphical abstract
Article
Parrot ownership is growing increasingly popular in the UK. Many veterinary professionals will find themselves treating a parrot at some point in their careers. Knowledge of the husbandry requirements of different species including housing, diet, hygiene, socialisation and enrichment is essential in order to evaluate these patients.
Chapter
In this section, species are listed and grouped according to similar gastrointestinal tract anatomy and physiology and the type of foods they consume. For each species, elements and their associated clinical signs caused by deficiency, toxicity, or exposure are listed.
Chapter
Ancillary diagnostic tests include a variety of routine or supplemental tests performed on birds to further progress in the diagnostic work-up once an initial work-up has been obtained. These tests tend to be more specific or targeted. In birds that are presented for emergency, diagnostic samples are frequently collected for bacterial cultures and sensitivity, molecular diagnostics, toxin assays, and for other disease-specific tests in order to diagnose the underlying condition leading to the presenting clinical signs. Various diagnostic endoscopic approaches are also discussed as endoscopy is often used in avian medicine as the ultimate noninvasive confirmatory diagnostic tool. Other ancillary diagnostic tests are presented as part of the diagnostic tools available to the avian emergency veterinarian such as infrared thermography, electromyography, ophthalmic, and parasitologic tests.
Chapter
Owing to their unique anatomy and physiology, avian emergencies can present a challenge to clinicians unfamiliar with these species. Because of their tendency to hide illnesses, emergency presentations in psittacine birds can be an acute exacerbation of an underlying disease. Despite the daunting differences between birds and the more commonly treated mammalian species, there are enough similarities that clinicians can feel comfortable offering basic emergency care to their avian patients. This chapter discusses common avian emergency presentations, differentials, diagnostics, and treatment options.
Preprint
Full-text available
The present study assessed the potential toxic levels of Cyanide and heavy metals in cassava our sold in selected township markets in Oke Ogun community. It aimed to determine the levels of Cyanide, Lead, Chromium and Arsenic, assess their health implications on the consumers as well as evaluation of allowable dietary concentrations according to WHO. Samples of nely ground fermented cassava our were purchased from ve (5) selected township markets (Igbeti, Kishi, Iseyin, Igboho and Shaki) using strati ed sampling method. The sample were rstly digested appropriately and further analyzed using Atomic Absorption Spectrophotometer (AAS). Data collected were analyzed using statistical package. Results obtained ranged showed that Cyanides (0.010Mg/L − 0.018Mg/L), Lead (0.028Mg/L-0.053Mg/L], Arsenic (0.006Mg/L-0.012Mg/L), and Chromium (0.034Mg/L-0.065Mg/L) respectively. In conclusion, Cassava our presently sold in Oke Ogun community markets were safe and suitable for human consumption without any dietary risk effects due to less concentration of these metals. It is therefore, recommended that cassava our sold should be frequently monitored and evaluation on a regular basis.
Article
Samples of corn available as wild-life feed from retailers throughout Georgia (USA) were collected during April 1997 and analyzed for aflatoxin to determine if levels harmful to wild turkeys (Meleagris gallopavo) were present. Three of 31 (10%) samples collected from a 40-country area were positive. An enzyme-linked immunosorbent assay qualitatively determined that two samples contained from 0 to 20 ppb aflatoxin. A chromatography analysis of a third sample measured 380 ppb total aflatoxin. A small percentage of our sample of wildlife feed collected during one season contained levels of aflatoxin that may cause harm to turkeys, especially poults. However, because aflatoxin levels ranging from 100 to 400 ppb may cause liver dysfunction and immunosuppression in turkey poults and other wildlife, grains known to be contaminated with aflatoxin at levels unacceptable for domestic animal feeds (greater than or equal to 100 ppb) should not be sold as wildlife feed. Further analyses of grains sold as wildlife feed should be conducted to address this potential problem.
Chapter
The process of digestion involves all of the mechanical and chemical changes that ingested food must undergo before it can be absorbed in the intestines. Mechanical changes include swallowing, maceration, and grinding of food in the muscular stomach; chemical digestion consists of secretion of enzymes from the mouth, stomach, intestines, and pancreas, of bile from the liver, of hydrochloric acid from the stomach, and of bacterial action.