Available via license: CC BY 4.0
Content may be subject to copyright.
veterinary
sciences
Review
The Role of Thiamine and Effects of Deficiency in
Dogs and Cats
Georgia Kritikos, Jacqueline M. Parr ID and Adronie Verbrugghe *
Department of Clinical Studies, Ontario Veterinary College, University of Guelph, 50 Stone Rd. E.,
Guelph, ON N1G 2W1, Canada; gkritiko@uoguelph.ca (G.K.); parr@uoguelph.ca (J.M.P.)
*Correspondence: averbrug@uoguelph.ca; Tel.: +1-519-824-4120
Academic Editor: Wendy Y. Brown
Received: 31 July 2017; Accepted: 17 November 2017; Published: 24 November 2017
Abstract:
Recent pet food recalls for insufficient dietary thiamine have highlighted the importance
of adequate thiamine intake in dogs and cats, as thiamine is an essential dietary nutrient with a
critical role in energy metabolism. Prolonged thiamine deficiency leads to clinical signs that can
span several organ systems, and deficiency can be fatal if not reversed. In this review, the current
knowledge of thiamine metabolism will be summarized. Dietary recommendations for dogs and
cats will be discussed, and the risk factors and clinical signs associated with thiamine deficiency will
be examined.
Keywords: vitamin B1; water-soluble vitamins; dog food; cat food; nutrient imbalance
1. Introduction
Thiamine (vitamin B
1
) is a water-soluble vitamin and an essential dietary nutrient in dogs and
cats. When in the form of thiamine diphosphate (TDP), it has a critical role as a cofactor in carbohydrate
metabolism, in the production of nucleotides and of nicotinamide adenine dinucleotide (NADH),
and for nervous system function. Other forms of thiamine include unphosphorylated (free) thiamine,
and thiamine with one or three phosphate groups (thiamine monophosphate and triphosphate,
respectively). These forms have not been as well-studied, but may be important for nervous system
function and may have additional functions that are not currently known [
1
–
3
]. Thiamine deficiency
has been reported in both dogs [
4
–
6
] and cats [
6
–
9
] and recent recalls of thiamine-deficient cat foods
have shown that this still continues to be a clinically relevant disease. Still, as the majority of research
has been done in species other than dogs and cats, further investigation of species-specific variations
of thiamine metabolism and requirements is warranted.
2. Dietary Thiamine Requirements in Dogs and Cats
Dogs and cats cannot synthesize thiamine, and therefore require thiamine as part of their diet [
10
].
According to nutritional requirements determined by the National Research Council (NRC), cats require
approximately two to four times more thiamine per day than dogs [
10
]. This is based on research
where thiamine deficiency was induced through feeding of a thiamine-deficient diet. Underlying
differences in metabolism between cats and dogs are currently unknown.
Dietary thiamine in dog and cat foods can be supplied in raw ingredients or can be added
as a synthetic supplement in the form of thiamine mononitrate or thiamine hydrochloride [
10
,
11
].
Presently, dietary thiamine recommendations have been determined for dogs and cats from case
reports and studies measuring varying rates of thiamine intake and resultant health status in dogs and
cats. In North America, many commercial pet food manufacturers follow Association of American
Feed Control Officials (AAFCO) guidelines when formulating diets, which historically are based on
Vet. Sci. 2017,4, 59; doi:10.3390/vetsci4040059 www.mdpi.com/journal/vetsci
Vet. Sci. 2017,4, 59 2 of 16
recommendations for adequate intake (AI) and recommended allowance (RA) by the NRC. Currently,
due to lack of data, there is no known safe upper limit (SUL) for thiamine [
12
]. Recommendations
for thiamine concentrations of adult dog and cat diets were updated by AAFCO in 2016 to match
the values recommended by the NRC [
13
]. In Europe, the Fédération Européenne de l’Industrie
des Aliments Pour Animaux Familiers (FEDIAF; European Pet Food Industry Federation) has its
own set of recommendations for nutrient intake in dogs and cats, which are based on the NRC’s AI
recommendations for adult dogs and cats [
14
]. The recommendations for dietary thiamine in adult
dogs and cats according to the NRC, AAFCO, and FEDIAF are summarized in Table 1.
Table 1.
Recommendations for dietary thiamine set by the NRC (2006), AAFCO (2017), and FEDIAF
(2017) for adult dogs and cats.
Organization Nutritional Basis Species Minimum Adequate Intake Minimum Recommended
Allowance
NRC [12]
DM Basis 1(mg/kg DMB) Cats 4.4 5.6
Dogs 1.8 2.25
Caloric Basis (mg/1000 kcal ME) Cats 1.1 1.4
Dogs 0.45 0.56
Metabolic Body Weight Cats 2(mg/kg0.67)0.11 0.14
Dogs (mg/kg0.75)0.059 0.074
AAFCO [13]DM Basis 1(mg/kg DMB) Cats – 5.6
Dogs – 2.25
Caloric Basis (mg/1000 kcal ME) Cats – 1.4
Dogs – 0.56
FEDIAF [14]
DM Basis 1(mg/kg DMB) Cats –4.4 3
5.9 4
Dogs –2.1 5
2.5 6
Caloric Basis (mg/1000 kcal ME) Cats –1.10 3
1.47 4
Dogs –0.54 5
0.62 6
AAFCO—Association of American Feed Control Officials; FEDIAF—Fédération Européenne de l’Industrie des
Aliments Pour Animaux Familiers (European Pet Food Industry Federation); NRC—National Research Council;
DMB—dry matter basis; ME—metabolisable energy;
1
Based on a dietary energy density of 4000 kcal ME/kg;
2
Based on a lean cat with an energy intake of 100 kcal x BW
0.67
;
3
Based on a cat with a daily energy requirement of
100 kcal/kg
0.67
;
4
Based on a cat with a daily energy requirement of 75 kcal/kg
0.67
;
5
Based on a dog with a daily
energy requirement of 110 kcal ME/kg
0.75
;
6
Based on a dog with a daily energy requirement of 95 kcal ME/kg
0.75
.
3. Thiamine Status in Healthy Dogs and Cats
Several methods exist in veterinary and/or human medicine to determine thiamine status.
Some are indirect methods that assess thiamine status, such as by measuring the activity of enzymes
for which thiamine is a cofactor, while others directly quantify concentrations of thiamine or its
phosphate esters.
3.1. Indirect Methods to Assess Thiamine Status
Thiamine status can be estimated using functional tests that measure the activity of enzymes for
which thiamine is a cofactor to determine thiamine status. These tests include erythrocyte transketolase
activity (ETKA) and the increase in transketolase (TK) activation that is measured after addition of
TDP
in vitro
, also called TDP effect [
15
–
18
]. There have been few reports in veterinary literature of
indirect thiamine status assessment in blood or tissues of dogs [
19
] and cats [
20
]. Moreover, these
tests are not without limitations, as results may be impacted by various physiological and technical
factors [21–24].
Thiamine diphosphate is a cofactor for pyruvate dehydrogenase, which converts pyruvate to
acetyl co-enzyme A (acetyl CoA) as part of aerobic metabolism. In the absence of adequate enzyme,
pyruvate is instead converted to lactate via lactic acidosis (i.e., anaerobic metabolism) [
17
]. In human
medicine, thiamine deficiency has been suspected based on the presence of elevated blood lactate
Vet. Sci. 2017,4, 59 3 of 16
concentrations [
25
,
26
]. Although blood lactate analysis is performed routinely in dogs and cats [
27
],
the link with thiamine status has not been investigated. Nonetheless, high urinary concentrations of
lactic acid have been linked with thiamine deficiency in dogs and cats [
28
,
29
]. Still, elevated lactate
concentrations in blood and urine are not specific to thiamine deficiency as hypoxic and non-hypoxic
lactic acidosis occurs with many disorders [
27
]. Simultaneous assessment of both lactate and pyruvate
concentrations may be a better predictor of thiamine status [30].
Thiamine status can also be inferred from assessment of urinary thiamine concentrations,
where urinary thiamine concentrations are measured per unit of creatinine to account for renal
function
[31–33]
. A significant correlation is present between thiamine intake and urinary thiamine
excretion in adult humans, however, excretion rates can vary widely between individuals [
33
]. Analysis
of urinary thiamine requires more evaluation before it can be used as a method to assess thiamine
status in dogs and cats.
Measurement of the growth response of microbial or protozoal species (e.g., yeast, algae) that
require thiamine have previously been used to assess whole blood thiamine status in dogs and
cats [
34
,
35
]. However, microbial methods have not been validated in dogs and cats. These methods
are also subject to limitations and are currently not commonly used for thiamine analysis [36].
3.2. Direct Methods to Assess Thiamine Status
Currently, the first choice method of thiamine analysis is to use high-performance liquid
chromatography (HPLC) to determine TDP concentrations in red blood cells [
37
]. This method,
validated in humans [
37
] and often used in canine and feline studies [
38
–
40
], is preferable as it directly
measures thiamine concentrations in blood and is therefore not impacted by the physiological processes
that can impact results of indirect analyses. Additionally, TDP is stable in whole blood for up to 48 h at
room temperature, and hemolysates and whole blood are stable at
−
70
◦
C for at least 7 months [
37
].
Thiamine concentrations in red blood cells obtained by HPLC are correlated with concentrations in
whole blood [37], and are also correlated with results of TK activation assays and TDP effect [37,41].
3.3. Thiamine Reference Range in Dogs and Cats
Little is known about blood thiamine status in dogs and cats. Thus, more research is required to
determine an accurate reference range for thiamine in both species.
A small study that compared whole blood thiamine status in one thiamine-deficient dog and six
control dogs reported lower thiamine status in the thiamine-deficient animal compared to controls,
with control dogs having a mean blood thiamine concentration of 95
µ
g/L (range: 84–104
µ
g/L) [
35
].
However, diets were not nutritionally balanced, and small sample sizes mean that results cannot be
generalized to the canine population. Another study determined whole blood thiamine concentrations
in 25 dogs and 29 cats and also used microbial methods, and found a median blood thiamine
concentration of 72
µ
g/L (range: 46–112
µ
g/L) in dogs, and a median of 48
µ
g/L (range: 20–90
µ
g/L)
in cats [
34
]. However, there were methodological concerns in this study. Dogs and cats in this study
included growing animals, adults, and senior animals. In addition, how the animals’ health status
was determined was not clarified and dietary intake was not assessed. Both of the above studies used
protozoal methods to assess thiamine status by measuring metabolically active forms of vitamins, and
while the authors of the second study stated that the method had been validated in humans and rats,
it was not validated in dogs and cats and is not a method that is used with any regularity.
In cats, a recent case series used HPLC to analyze TDP status in whole blood of three healthy
animals and compared this to the thiamine status of cats diagnosed with thiamine deficiency.
The authors found blood TDP concentrations of 47.0
±
7.8
µ
g/L in the healthy cats [
38
]. The TDP
status of whole blood in 64 adult dogs has also been determined using HPLC. Dogs had a mean
±
SD baseline blood TDP concentration of 89.7
±
20.7
µ
g/L, which represented a thiamine status of
dogs being fed a variety of diets [
39
]. The authors later put the dogs on one of four diets that each
contained known thiamine contents for four months, and found that thiamine status did not differ
Vet. Sci. 2017,4, 59 4 of 16
significantly between these diets, nor did it differ from the baseline value for any of the diets. However,
thiamine concentrations were not adjusted based on hematocrits when conducting thiamine analyses.
This could have affected the observed results, as TDP in the blood is predominantly found in red blood
cells [
42
], and thus any fluctuations in hematocrit could affect resultant blood thiamine concentrations.
More recently, an assessment of RBC thiamine concentrations in 22 dogs and eight cats was
conducted using HPLC [
40
]. Blood thiamine concentrations were adjusted based on animals’
hematocrits. All dogs and cats had been put on one of three complete and balanced canine or
feline diets, respectively. Mean
±
SD TDP concentrations for dogs and cats were a respective
311.4 ±46.8
and 868.2
±
344.0
µ
g/L. Unphosphorylated thiamine (free thiamine) status of dogs
was reported to be
350.3 ±50.3 µg/L
, but was not assessed in cats [
40
]. The reason for the higher TDP
concentrations observed in this study in comparison to previous studies is unknown, but may have
been related to differences in methodology compared to previous studies [
40
]. Additionally, in blood
cells, thiamine diphosphate is typically the predominant form, while free thiamine makes up a much
smaller proportion [
17
], which is in contrast with the findings of this study. However, this study was
the first to assess free thiamine status in dogs. Additional research is required to determine a reference
range for TDP and free thiamine in dogs and cats.
4. Thiamine Deficiency in Dogs and Cats
4.1. Prevalence of Thiamine Deficiency
The prevalence of thiamine deficiency in dogs and cats, both healthy animals and patients with
disease, is currently unknown.
However, more information is available from human studies that typically examine the prevalence
of thiamine deficiency in specific diseases, by utilizing indirect methods (ETKA and TDP effect)
or direct methods (HPLC) to assess thiamine status. When compared to the thiamine status of
hospitalized control subjects, the prevalence of poor thiamine status has been found to be elevated
in individuals with diabetes mellitus (type 1 and 2) [
43
], congestive heart failure [
32
], and chronic
alcoholism [
44
]. However, comorbidities, use of certain medications, diet or nutritional status, and age
can impact thiamine status and should be considered as potential factors influencing results in these
populations. Thiamine deficiency in elderly people in the UK has been reported to occur in 8–31% of
non-institutionalized individuals and between 23–40% in individuals living in nursing homes [
45
].
One study found that 10% of human intensive care unit (ICU) inpatients with septicemia are thiamine
deficient upon presentation, which increased to 20% within 72 h of admission [
46
]. Thiamine deficiency
has been reported in 33–91% of hospital patients with heart disease [47]. Overall, approximately 20%
of adult ICU inpatients are thiamine deficient upon admission [48].
4.2. Risk Factors and Etiology of Thiamine Deficiency
4.2.1. Inadequate Dietary Thiamine Intake
Thiamine is an essential dietary nutrient and is not sequestered in large quantities in the body,
with excess dietary thiamine being excreted in urine [
10
]. Consistent thiamine intake is therefore
critical to prevent deficiency.
a. Unconventional and Alternative Diets
Unconventional and alternative diets include cooked or raw homemade diets, as well as
commercially-produced diets that resemble homemade diets or that require some preparation from
owners (e.g., addition of water or meat) [
49
]. These types of diets for pets are a growing trend in
North America, as owner concerns or suspicions about the nutritional quality of commercial pet foods
increase [50].
The majority of these diets are not nutritionally adequate [
49
,
51
,
52
]. There have been reports
of dogs and cats developing signs of thiamine deficiency as a result of being fed unbalanced
Vet. Sci. 2017,4, 59 5 of 16
homemade cooked diets [
4
,
8
,
35
]. Nutritional analyses have shown that homemade diets tend to
lack essential macro- and micro-nutrients, including thiamine, when they are intended for adult
maintenance [
51
,
53
]. Insufficient thiamine has also been found in homemade diets intended for the
treatment or management of specific diseases [
54
,
55
]. Additionally, nutrient imbalances have been seen
in homemade and commercial raw diets, though thiamine content has not specifically been assessed in
these diets [52,56,57].
Canine diets formulated by both veterinarians and non-veterinarians often do not meet nutritional
requirements for dogs [
51
]. Thus, homemade diets should be formulated by board-certified veterinary
nutritionists to ensure nutritional adequacy. Even when homemade diets have been formulated to meet
nutritional adequacy recommendations, there may be variability in the exact nutritional composition of
the ingredients [
58
]. This makes it difficult to keep the nutrient content of homemade diets consistent
between batches. There are also concerns with owners not closely following the recipe, as owners
may switch ingredients or alter the preparatory methods of the recipe without consulting a veterinary
nutritionist, which can lead to unbalanced diets [58,59].
b. Conventional Pet Food
In addition to homemade diets, conventional dry and wet diets may contain inadequate
thiamine concentrations.
In the United States and Australia, over 90% of dogs receive conventional dry or wet dog foods
as at least 50% of their diet [
60
,
61
]. Also, cat owners have been found to be more likely to feed
conventional pet foods than dog owners [
61
]. Conventional cat foods make up at least 50% of the
diet for more than 98% of cats [
60
,
61
]. Since dogs and cats tend to receive most of their nutrition from
conventional diets, it is imperative that these diets contain adequate concentrations of essential dietary
nutrients, including thiamine.
Nonetheless, diets intended for intermittent or supplemental feeding only may provide
inadequate thiamine and subsequently lead to development of signs of thiamine deficiency [
38
].
Thus, feeding conventional diets that follow AAFCO or FEDIAF recommendations and that contain a
statement on their label declaring that they are complete and balanced for the appropriate species and
life stage, minimizes the risk of poor dietary thiamine intake in dogs and cats.
Still, even with complete and balanced conventional pet foods, the risk for thiamine deficiency
may exist. Thiamine is very labile and readily degrades under different conditions, including exposure
to oxygen, heat, and neutral and alkaline pH [
62
–
66
]. This can pose problems for ensuring that
processed diets meet requirements for thiamine concentrations. In pelleted and extruded ruminant
feed, thiamine hydrochloride and mononitrate degradation is approximately 4.0% and 4.5% per month,
respectively [
67
]. Cooking of thiamine-containing foods has variable losses of thiamine, as the exact
cooking procedure will lead to different percentages of loss of thiamine [
66
]. The effect of freezing on
thiamine retention is currently unknown. Studies typically examine freezing in addition to another
form of processing (e.g., cooking, blanching, canning) [
68
–
71
], making results difficult to interpret.
One study found that frozen spinach contained higher thiamine content after storage compared to
baseline values, but the authors were unable to determine a reason for this result [72].
Pet food manufacturers may compensate for anticipated thiamine degradation by adding
additional synthetic thiamine prior to cooking (i.e., extrusion or baking for dry food, and canning
or cooking for wet food). Despite this, the final products may not contain adequate quantities of
thiamine. Differences in manufacturing procedures between factories and between specific diets may
differentially affect thiamine losses, making it difficult to estimate general losses across all dry or
wet diets. In general, higher cooking temperatures during extrusion can lead to greater losses of
thiamine compared to lower cooking temperatures [
67
,
73
]. However, a recent review examining effects
of extrusion on dry pet foods also notes that while higher temperatures may lead to greater thiamine
losses, different retention times during extrusion can also lead to variability in thiamine losses between
diets [74].
Vet. Sci. 2017,4, 59 6 of 16
Wet foods seem to be especially susceptible to thiamine deficiency, based on pet food recall
information. Since 2010, six recalls of commercial cat foods have occurred for suspected or confirmed
thiamine deficiency in North America. These diets all had AAFCO nutritional adequacy claims. Recalls
consisted of 17 commercial canned cat foods, compared to five extruded dry cat foods and one raw
cat food [
75
]. The Food Standards Agency (FSA) in the United Kingdom has also reported a recent
thiamine-related recall for three dry extruded cat foods [
76
], and more recently, there has been a recall of
eight canned cat foods in Australia that have been found to contain insufficient thiamine [
77
]. A recent
study examining thiamine concentrations in samples of 90 commercial canned cat foods in the United
States, all of which claimed to meet AAFCO guidelines, found that 12 of these foods (13.3%) were
thiamine-deficient compared to AAFCO (2014) recommended concentrations, and 14 foods (15.6%)
were deficient compared to the slightly higher NRC recommended concentrations [
78
]. With the 2016
increase in AAFCO recommended concentrations to match those of the NRC, the number of diets in
this study that were deficient according to AAFCO recommendations would have been comparable to
the NRC (15.6%). The authors of this study also found that patéfoods and foods produced by small
manufacturing companies had a higher proportion of low thiamine concentrations than non-paté
foods and foods produced by large manufacturing companies, respectively. The authors speculated
that these differences may have been due to thiamine degradation as a result of the extra processing
required to produce patéfoods, as well as the ability of larger manufacturers to exert better quality
control and conduct more frequent testing for thiamine. The cross-sectional nature of this study, as well
as the possibility of inter-batch variation between products and the absence of random selection from
all commercially available products, may have impacted results. Additionally, a study that reported
thiamine retention after 18 months of storage found 0% thiamine losses in canned dog and cat food
over 18 months of storage, but reported storage-related losses of 34.2% and 57.5% in extruded dry dog
and cat food, respectively [
79
]. However, the original research could not be consulted as this research
is no longer archived at its publisher, and storage conditions of the diets are therefore unknown.
c. Presence of Anti-Thiamine Compounds
Anti-thiamine compounds or thiamine agonists are synthetic or natural compounds that inactivate
thiamine by changing thiamine’s chemical structure.
Thiamine is unique in that it is the sole vitamin for which an enzyme has evolved that can
destroy it. This enzyme, thiaminase, is present in the flesh of dead fish and in some shellfish and
bacterial species. Thiaminases cleave thiamine to make it biologically inactive [
66
,
80
,
81
]. Thiamine
deficiency has been documented in animals that have been fed diets containing predominantly
raw fish, including dogs and foxes [
4
,
82
]. Thiaminases present in fish are denatured by high heat,
with varying sensitivity [
83
,
84
]. Therefore, the risk for thiamine deficiency may be present in both
raw and inadequately cooked fish-based diets for dogs and cats. These diets may benefit from adding
additional supplemental thiamine during processing or as an oral supplement during feeding.
Additionally, the use of sulfites such as sulfur dioxide to preserve meats has been implicated
in thiamine loss in foods. There have been documented cases of dogs and cats developing signs of
thiamine deficiency after eating sulfite-preserved meat as a primary component of their diet [
5
,
6
,
9
].
This is likely due to sulfur’s actions in converting thiamine to thiamine disulfide, as this form of
thiamine has poor bioavailability in the body [
66
]. This thiamine-destroying effect occurs in non-meat
products, such as parboiled rice, as well [
85
]. In commercial pet foods, the use of sulfur as a preservative
could lead to the loss of bioavailable thiamine and subsequent thiamine deficiency in pets when fed
these commercial diets as the primary source of nutrition. Presently, sulfites are not permitted in foods
containing meat or in sources of thiamine by the United States Food and Drug Administration [
86
],
and AAFCO has similar restrictions on the usage of sulfur and sulfites [
13
]. This decreases the
likelihood of thiamine deficiency caused by sulfites in pets in North America.
Plant-derived anti-thiamine factors, heat-stable compounds known as polyhydroxyphenols,
which include caffeic acid, phenols, flavonoids, and tannins, are present in certain plants
Vet. Sci. 2017,4, 59 7 of 16
and destroy thiamine by an oxidative process that transforms it to non-absorbable thiamine
disulfide [17,63,66,87–90]. Plants containing polyhydroxyphenols include coffee, tea, and some fruits
and vegetables, such as blueberries and red cabbage [
17
]. While research in dogs and cats has not
been conducted to determine the effect of plant-derived anti-thiamine factors on blood nutrient
concentrations, the presence of anti-thiamine factors in plant matter may be of importance for dogs
and cats being fed homemade diets or large portions of table scraps containing ingredients with
these compounds.
d. Interactions with Other Nutrients
Little has been documented about the interactions of thiamine with other nutrients. A study in
kittens showed that high concentrations of dietary glutamic acid led to increased dietary thiamine
requirements [
20
]. The reason for this increased requirement is unknown. Conversely, dietary
protein and fat have been found to reduce the metabolic demand for thiamine when compared to
carbohydrates [
91
]. This is likely due to the role of thiamine as a cofactor in carbohydrate metabolism
and the increased requirement for thiamine with activation of the Krebs cycle for the catabolism of
dietary carbohydrates.
In adult humans, increasing one’s consumption of carbohydrates but maintaining a constant
thiamine intake may lead to significant declines in plasma and urine thiamine content, but may
not affect ETKA or fecal thiamine content [
31
]. Research determining the relationship between
carbohydrate intake and thiamine requirements has not been conducted in dogs and cats. This is an
area that warrants further research to better delineate thiamine requirements of complete and balanced
commercial dog and cat foods that may contain varying carbohydrate concentrations.
e. Inadequate Food Intake
While insufficient dietary thiamine concentrations can be a risk factor for deficiency in dogs and
cats ingesting their daily caloric requirements, decreased food intake (hyporexia) or complete lack
of food intake (anorexia) can also increase the risk. In these cases, the daily recommended intake of
thiamine that is necessary to meet the body’s consistent requirement for thiamine is not ingested.
f. Life Stage Requirements
Elderly individuals may be at higher risk of developing thiamine deficiency, as thiamine
absorption is thought to become less efficient as humans age. Thiamine status using ETKA, tends to
decline with age [
18
,
22
]. However, while analysis of RBCs by HPLC showed no difference between
elderly and young adult groups [
18
], other research showed an age-related decline in TDP status [
92
].
Elderly individuals may have lower thiamine intakes than young adults, but intake may still meet
nutrient recommendations for adult humans [
18
]. As few studies assessed dietary thiamine intake
in relation to thiamine status, it is unclear if elderly humans have low thiamine status due to lower
thiamine intake, as a result of age-related changes in absorption, or due to comorbidities. More research
is therefore required to determine the effect of aging on thiamine metabolism in humans and even
more so in pets, as currently no research is available investigating the effect of aging on thiamine status,
metabolism and requirement of dogs and cats.
4.2.2. Inadequate Thiamine Uptake
Dogs and cats may develop signs of thiamine deficiency despite ingesting nutritionally adequate
concentrations of thiamine, which may be due to several factors affecting the uptake or metabolism of
thiamine once it enters the body.
One such factor is intestinal malabsorption or maldigestion, which may occur with chronic GI
diseases. More specifically, in humans, inflammatory bowel disease and gastric cancer have been
found to be associated with symptoms of thiamine deficiency [
93
,
94
]. Thiamine deficiency can occur
Vet. Sci. 2017,4, 59 8 of 16
as a result of chronic vomiting as thiamine is unable to travel through the GI tract for absorption [
95
].
Also, chronic diarrhea can lead to poor intestinal uptake of thiamine.
Intestinal absorption of thiamine is regulated by two thiamine transporters (THTR), THTR-1
and THTR-2 [
96
]. Defects in these transporters may therefore be associated with thiamine deficiency.
In cats, feline leukemia virus (FeLV), specifically the virus form known as subgroup A (FeLV-A),
uses THTR-1 as a receptor to enter cells, which subsequently prevents thiamine uptake through these
receptors
[97,98]
. However, due to THTR-2 not being affected by this mechanism, the risk of developing
thiamine deficiency as a result of FeLV may be low. In dogs, Alaskan Husky Encephalopathy
(AHE) is a generally fatal neurological disease that manifests in juvenile Alaskan Huskies, and the
genomes of affected dogs have been found to contain a mutation in the gene that produces THTR-2,
SLC19A3
[99,100]
. Dogs with AHE have a novel defect in one of two SLC19A3 paralogs that has been
found to lead to poor expression of this gene [
19
,
100
]. Clinical signs of this disease may therefore
be related to thiamine deficiency of nervous tissues due to an inability to provide enough thiamine
transporters to compensate for the low disease-related SLC19A3 paralog expression [100].
Several disease states are also associated with thiamine deficiency. One such disease is congestive
heart failure (CHF). A decreased thiamine status was found in humans with CHF, possibly as a
result of diuretic-induced urine thiamin excretion, disease severity, malnutrition, and advanced
age [
32
]. Individuals receiving thiamine via multivitamin supplementation were also less likely to
have thiamine deficiency [
32
]. Cardiac failure has been experimentally induced in dogs given a
thiamine-deficient diet [
101
], though some dogs in this study did not develop heart failure despite
ingesting a thiamine-deficient diet. The diet that was fed was not complete and balanced and was
potentially deficient in other nutrients as well, which may have confounded results. The relationship
between CHF and thiamine deficiency in dogs and cats therefore requires further study. Moreover, in
patients with CHF, the use of certain medications, such as diuretics, should also be considered when
examining thiamine status.
4.2.3. Excessive Thiamine Excretion
Because of the kidneys’ role in excretion and re-uptake of thiamine, diseases affecting the kidneys
have an effect on thiamine status. In any disease associated with polyuria, the rate of urinary excretion
is expected to be increased due to thiamine’s water-soluble nature. Research is scarce in dogs and
cats. However, in humans, decreased renal function associated with type 1 and type 2 diabetes
has been linked to thiamine deficiency due to excess excretion of thiamine compared to healthy
individuals [
43
]. Moreover, in humans, a link also exists between chronic kidney disease (CKD)
and thiamine deficiency [
48
]. Clinically, CKD is associated with polyuria and polydipsia in dogs
and cats, and can also result in anorexia or hyporexia [
102
], all of which are risk factors of thiamine
deficiency. Despite this, a recent study in dogs with CKD showed that these dogs had a higher blood
TDP concentration compared to healthy controls [
103
]. The authors hypothesized that decreased renal
function led to lower urinary thiamine excretion, though they did not assess rates of urinary thiamine
excretion between dogs with CKD and controls. More research is therefore required to determine the
effect of CKD on thiamine excretion.
Additionally, diuretics may increase the risk for thiamine deficiency due to the increased urinary
flow rates associated with the use of diuretics. A study examining urinary thiamine excretion in
rats compared different diuretics at increasing dosages, and found that furosemide and mannitol,
as well as volume loading with isotonic saline solution, led to significantly higher urinary thiamine
excretion compared to baseline values [
104
]. Increasing thiamine excretion was found to be related to
increasing urine output, and urinary thiamine losses also tended to increase with increasing diuretic
dosages. The authors reported that other diuretics tested in this study (chlorothiazide, acetazolamide,
and amiloride) also showed higher urinary thiamine excretion compared to baseline, but detailed data
for these medications were not provided and statistical significance was not reported.
Vet. Sci. 2017,4, 59 9 of 16
4.3. Clinical Signs of Thiamine Deficiency
Signs of thiamine deficiency tend to be non-specific and can involve multiple organ systems [
105
],
which can make the diagnosis challenging. In general, however, signs of thiamine deficiency in both
dogs and cats are split into three progressive stages that are seen in both species: an induction stage,
a critical stage, and a terminal stage [10].
The first stage, induction, occurs within one to two weeks of deficiency, and is characterized by a
combination of vomiting, lethargy, and hyporexia or anorexia, though the animal’s behaviour may
remain otherwise unchanged [
4
,
28
,
106
–
108
]. Few other signs occur at this stage. However, weight loss
due to chronic poor food intake may be noted [6,28].
If deficiency is not reversed during the induction stage, the animal will enter the critical stage,
and signs of nervous system damage will appear. In dogs and cats, these can include ataxia,
paraparesis, nystagmus, delayed pupillary light response and blindness, recumbency, and increasingly
poor proprioception, as well as seizures [
4
,
5
,
9
,
28
,
35
,
38
,
106
,
109
]. Cats may also exhibit cervical
ventroflexion [
106
,
109
] and dyspnea [
9
,
106
]. Cardiovascular signs during chronic deficiency may
include arrhythmias and bradycardia [110].
The terminal stage of thiamine deficiency begins after approximately a month of severe deficiency,
and involves a rapid worsening of signs until death occurs. It is fatal within a few days unless
supplementation occurs immediately [
105
]. Most cases of thiamine deficiency are diagnosed at the
terminal stage [105].
4.4. Diagnosis of Thiamine Deficiency
Thiamine deficiency is poorly reflected on routine bloodwork. A complete blood count and
serum biochemistry profile may be unremarkable in thiamine-deficient animals, even after prolonged
deficiency [
5
,
7
,
28
,
38
,
109
]. High concentrations of organic acids that indicate impairment in thiamine
metabolism may be used to diagnose thiamine deficiency [
28
,
29
]. In humans, hyperlactatemia has been
noted as a possible symptom of thiamine deficiency, which does not respond to treatment with sodium
bicarbonate and can be aggravated by administration of glucose [
25
,
26
]. Elevated lactate concentrations
in urine may occur in dogs with thiamine deficiency [
28
,
110
], but these are not always present in
cats [
29
]. As well, elevated lactate concentrations in plasma and cerebrospinal fluid (CSF) are not always
present in dogs during thiamine deficiency [
100
], and CSF results can be unremarkable [
7
,
106
,
109
].
Blood pyruvate concentrations may be elevated in dogs with thiamine deficiency [110].
While several methods exist to assess thiamine status in blood, both directly and indirectly,
analysis of thiamine status in veterinary patients is likely not regularly conducted, as thiamine
status tends to not be reported in veterinary case reports pertaining to suspected thiamine deficiency.
This may be due to the lack of an established reference range for thiamine status in dogs and
cats, as well as poor availability of laboratories that routinely conduct thiamine analyses. Instead,
thiamine deficiency in dogs and cats is typically diagnosed based on clinical signs and the presence
of risk factors (e.g., unbalanced diet), and diagnosis is confirmed if signs reverse after thiamine
supplementation
[5,8,28,29,109,111,112]
. An assessment of risk factors for thiamine deficiency should
be accompanied by a nutritional assessment, such as the World Small Animal Veterinary Association
(WSAVA) nutritional assessment guidelines, to rule out a nutritional cause [
113
]. Patients consuming
raw or cooked homemade diets may be more likely to develop nutritional deficiencies due to
consuming nutritionally unbalanced diets [
50
], which can include deficient thiamine intake. However,
thiamine deficiency can also occur with commercial diets. Suspicion of a dietary cause of deficiency
can be confirmed by analyzing a sample of the patient’s food for its total thiamine concentration.
Magnetic resonance imaging (MRI) can be used to reveal brain lesions commonly seen in thiamine
deficiency. These tend to consist of symmetrical, bilateral lesions in the brainstem that primarily affect
grey matter [
29
,
114
]. On histopathology, lesions are especially present in the nuclei of the caudal
colliculi, and may either be spongy or involve cell degeneration and hypertrophy [
4
,
5
,
9
,
29
,
38
,
114
].
Lesions may also be present in the cerebral cortex, cerebellar noduli, rostral colliculi, and suprasplenial
Vet. Sci. 2017,4, 59 10 of 16
gyri of the caudal cortex, and the medial vestibular nuclei [
4
,
5
,
108
,
109
,
114
]. One report revealed
unremarkable MRI findings despite presenting with clinical signs of thiamine deficiency in a cat,
though it is unclear if signs reversed due to the cat having received supplemental thiamine for several
days prior to MRI, or if no abnormalities had been present prior to supplementation [106].
4.5. Treatment of Thiamine Deficiency
Treatment of thiamine deficiency requires thiamine supplementation, either as a vitamin
supplement or included in a complete and balanced diet. If thiamine deficiency is suspected due to an
unbalanced diet, and if the suspected deficiency is discovered before the onset of advanced clinical
signs, administration of supplemental thiamine and a change to a complete and balanced diet may be
all that is required to prevent the appearance of further signs of deficiency [4,111].
As one of the signs of thiamine deficiency is anorexia [
10
], oral administration of thiamine as
part of a complete and balanced commercial canned critical care diet or a veterinary liquid diet may
require a feeding tube if the patient refuses or is unable to eat independently. Enteral feeding of
patients with prolonged poor food intake should begin at one-third of the patient’s resting energy
requirements [RER = 70
×
(body weight
kg0.75
)], then increase to 2/3 and then to the patient’s full RER
every 24 h or slower in order to avoid metabolic complications [
115
]. Veterinary liquid diets tend to
contain adequate concentrations of thiamine. A recent study examined nutrient composition of seven
veterinary liquid feline diets and found thiamine in sufficient concentrations in all but one analyzed
diet [
116
]. Adequate thiamine supplementation is therefore expected in the majority of veterinary
liquid diets. This suggests that supplying thiamine through a complete and balanced canned critical
care diet or veterinary liquid diet may be a viable option for patients that are able to be fed enterally.
An oral thiamine supplement may also be administered to patients; however, large oral doses of
synthetic thiamine may be poorly absorbed in dogs [
117
], which would suggest that other forms of
supplementation may be more effective.
Parenteral thiamine, typically in the form of thiamine hydrochloride, may be administered via
intramuscular (IM), intravenous (IV), or subcutaneous (SQ) injections [
105
]. In the authors’ experience,
dilution with sterile saline reduces potential injection-related discomfort in patients receiving SQ
thiamine injections [
40
]. The ideal dose for supplemental thiamine is not currently known, and dosages
reported in the literature for parenteral supplementation vary. In adult cats, dosages range from
20–300 mg per day [
7
,
8
,
29
,
38
,
106
,
111
], while in adult dogs they can range from 50–1250 mg per
day [
5
,
28
,
35
]. Supplementation may begin with a loading dose of thiamine with subsequent smaller
doses, or may utilize consistent dosages throughout treatment. Supplementation may occur as multiple
doses per day, or may be administered once daily. However, dosages tend to be reported per animal
rather than per kilogram, and the routes of thiamine administration vary between cases, therefore
comparisons of precise dosages are difficult. There have been reports of severe reactions, such as
anaphylaxis; neuromuscular, ganglionic, and vagus blockade; apnea; and hypotension associated with
IV administration in dogs and cats [
10
,
118
], and it is therefore discouraged as a method of thiamine
supplementation [105].
4.6. Prognosis and Outcome of Thiamine Deficiency
The severity of thiamine deficiency may have an impact on outcomes. To date, no research is
available in dogs and cats. Nonetheless, a retrospective study of human hospital patients found that
mortality rates were higher in human patients with severe thiamine deficiency compared to patients
with slight or no deficiency [
119
]. However, due to the retrospective nature of this study, the researchers
were unable to quantify illness severity or nutritional status in patients.
Signs of thiamine deficiency may begin to resolve within several hours after supplementation
[
5
,
29
,
107
,
111
]. One case series found that 76% (13/17) of cats being fed a thiamine-deficient diet
showed significant improvement within one week when treatment consisted of supplementation in
addition to a diet change to a complete and balanced feline diet [
106
]. Resolution of MRI signs may be
Vet. Sci. 2017,4, 59 11 of 16
seen within days of beginning thiamine supplementation [
8
,
28
,
106
], but MRI abnormalities may persist
for several weeks [
28
]. Additionally, clinical signs may remain despite absence of MRI signs [
28
,
106
].
Some neurological signs may persist for days to months after treatment ends [
6
,
10
,
28
,
29
,
106
], and
neurological signs such as mild ataxia may persist for up to two years after treatment [106].
5. Conclusions
As thiamine is a dietary requirement in mammals, consistent and adequate daily intake is essential
to prevent deficiency. This can be through a complete and balanced commercial diet, or a nutritionally
balanced homemade diet formulated by a veterinary nutritionist to meet a dog or cat’s nutrient
requirements for their respective life stage. Signs of deficiency in dogs and cats are non-specific in
the induction stage, involve multiple organ systems, and diagnostic tests are not readily available,
making early diagnosis of thiamine deficiency a challenge. As a result, most cases are diagnosed in
the terminal stage, where quick identification based on clinical signs is critical and treatment must
commence immediately to ensure the survival of the deficient dog or cat. The prevalence of thiamine
deficiency in companion animals presenting to veterinary hospitals and ICUs is currently unknown.
Parenteral thiamine is routinely administered in human hospitals for patients considered to be at high
risk for deficiency [
120
], but the same is not necessarily true for dogs and cats presenting to veterinary
hospitals. Thus, the need for routine thiamine administration in dogs and cats must be assessed in
order to determine whether thiamine supplementation should be included as a routine part of medical
care for dogs and cats presenting to veterinary ICUs.
Author Contributions:
Georgia Kritikos, Jacqueline M. Parr and Adronie Verbrugghe contributed to
manuscript drafting.
Conflicts of Interest:
All authors state no conflict of interest. Authors disclose that Jacqueline M. Parr is a paid
employee of Royal Canin Canada and Adronie Verbrugghe is the Royal Canin Endowed Chair in Canine and
Feline Clinical Nutrition at the Ontario Veterinary College.
References
1.
Manzetti, S.; Zhang, J.; van der Spoel, D. Thiamin function, metabolism, uptake, and transport. Biochemistry
2014,53, 821–835. [CrossRef] [PubMed]
2.
Bettendorff, L.; Wins, P. Biochemistry of thiamine and thiamine phosphate compounds. In The Encyclopedia of
Biological Chemistry; Lennarz, W.J., Lane, M.D., Eds.; Academic Press: Cambridge, MA, USA, 2013; Volume 1,
pp. 202–209.
3.
Gangolf, M.; Czerniecki, J.; Radermecker, M.; Detry, O.; Nisolle, M.; Jouan, C.; Martin, D.; Chantraine, F.;
Lakaye, B.; Wins, P.; et al. Thiamine status in humans and content of phosphorylated thiamine derivatives in
biopsies and cultured cells. PLoS ONE 2010,5. [CrossRef] [PubMed]
4.
Houston, D.M.; Hulland, T.J. Thiamine deficiency in a team of sled dogs. Can. Vet. J.
1988
,29, 383–385.
[PubMed]
5.
Singh, M.; Thompson, M.; Sullivan, N.; Child, G. Thiamine deficiency in dogs due to the feeding of sulphite
preserved meat. Aust. Vet. J. 2005,83, 412–417. [CrossRef] [PubMed]
6.
Studdert, V.P.; Labuc, R.H. Thiamin deficiency in cats and dogs associated with feeding meat preserved with
sulphur dioxide. Aust. Vet. J. 1991,68, 54–57. [CrossRef] [PubMed]
7.
Loew, F.M.; Martin, C.L.; Dunlop, R.H.; Mapletoft, R.J.; Smith, S.I. Naturally-occurring and experimental
thiamin deficiency in cats receiving commercial cat food. Can. Vet. J. 1970,11, 109–113. [PubMed]
8.
Palus, V.; Penderis, J.; Jakovljevic, S.; Cherubini, G.B. Thiamine deficiency in a cat: Resolution of MRI
abnormalities following thiamine supplementation. J. Feline Med. Surg.
2010
,12, 807–810. [CrossRef]
[PubMed]
9.
Steel, R.J. Thiamine deficiency in a cat associated with the preservation of ‘pet meat’ with sulphur dioxide.
Aust. Vet. J. 1997,75, 719–721. [CrossRef] [PubMed]
10.
National Research Council. Vitamins. In Nutrient Requirements of Dogs and Cats; National Academies Press:
Washington, DC, USA, 2006; pp. 193–245.
11. Gregory, J.F. Bioavailability of Thiamin. Eur. J. Clin. Nutr. 1997,51, S34–S37. [PubMed]
Vet. Sci. 2017,4, 59 12 of 16
12.
National Research Council. Nutrient Requirements and Dietary Nutrient Concentrations. In Nutrient
Requirements of Dogs and Cats; National Academies Press: Washington, DC, USA, 2006; pp. 354–370.
13.
Association of American Feed Control Officials (AAFCO). Model Bill and Regulations. In AAFCO 2017 Official
Publication; Association of American Feed Control Officials Inc.: Champaign, IL, USA, 2017; pp. 136–218.
14.
Nutrition-FEDIAF. A Necessity: Nutrition Quality. Available online: http://www.fediaf.org/self-regulation/
nutrition/ (accessed on 20 July 2017).
15.
Balk, L.; Hägerroth, P.; Åkerman, G.; Hanson, M.; Tjärnlund, U.; Hansson, T.; Hallgrimsson, G.T.; Zebühr, Y.;
Broman, D.; Mörner, T.; et al. Wild birds of declining European species are dying from a thiamine deficiency
syndrome. Proc. Natl. Acad. Sci. USA 2009,106, 12001–12006. [CrossRef] [PubMed]
16.
Croft, L.; Napoli, E.; Hung, C.K.; St. Leger, J.; Gearhard, S.; Heym, K.; Wong, S.; Sakaguchi, D.; Lin, A.;
Puschner, B.; et al. Clinical evaluation and biochemical analyses of thiamine deficiency in Pacific harbor seals
(Phoca vitulina) maintained at a zoological facility. J. Am. Vet. Med. Assoc.
2013
,243, 1179–1189. [CrossRef]
[PubMed]
17.
Gropper, S.S.; Smith, J.L. Water-Soluble Vitamins. In Advanced Nutrition and Human Metabolism, 6th ed.;
Gropper, S.S., Smith, J.L., Eds.; Wadsworth/Cengage Learning: Belmont, CA, USA, 2013; pp. 319–325.
18.
O’Rourke, N.P.; Bunker, V.W.; Thomas, A.J.; Finglas, P.M.; Bailey, A.L.; Clayton, B.E. Thiamine status of
healthy and institutionalized elderly subjects: Analysis of dietary intake and biochemical indices. Age Ageing
1990,19, 325–329. [CrossRef] [PubMed]
19.
Vernau, K.; Napoli, E.; Wong, S.; Ross-Inta, C.; Cameron, J.; Bannasch, D.; Bollen, A.; Dickinson, P.;
Giulivi, C. Thiamine deficiency-mediated brain mitochondrial pathology in Alaskan huskies with mutation
in SLC19A3.1.Brain Pathol. 2015,25, 441–453. [CrossRef] [PubMed]
20.
Deady, J.E.; Anderson, B.; O’Donnell, J.A., III; Morris, J.G.; Rogers, Q.R. Effects of level of dietary glutamic
acid and thiamin on food intake, weight gain, plasma amino acids, and thiamin status of growing kittens.
J. Nutr. 1981,111, 1568–1579. [PubMed]
21.
Puxty, J.A.H.; Haskew, A.E.; Ratcliffe, J.G.; McMurray, J. Changes in erythrocyte transketolase activity and
the thiamine pyrophosphate effect during storage of blood. Ann. Clin. Biochem.
1985
,22, 423–427. [CrossRef]
[PubMed]
22.
Markkanen, T.; Heikinheimo, R.; Dahl, M. Transketolase activity of red blood cells from infancy to old age.
Acta Haematol. 1969,42, 148–153. [CrossRef] [PubMed]
23.
Kaczmarek, M.J.; Nixon, P.F. Variants of transketolase from human erythrocytes. Clin. Chim. Acta
1983
,130,
349–356. [CrossRef]
24.
Kaufmann, A.; Uhlhaas, S.; Friedl, W.; Propping, P. Human erythrocyte transketolase: No evidence for
variants. Clin. Chim. Acta 1987,162, 215–219. [CrossRef]
25.
Amrein, K.; Ribitsch, W.; Otto, R.; Worm, H.C.; Stauber, R.E. Severe lactic acidosis reversed by thiamine
within 24 h. Crit. Care 2011,15. [CrossRef] [PubMed]
26.
Oriot, D.; Wood, C.; Gottesman, R.; Huault, G. Severe lactic acidosis related to acute thiamine deficiency.
J. Parenter. Enter. Nutr. 1991,15, 105–109. [CrossRef] [PubMed]
27.
Sharkey, L.C.; Wellman, M.L. Use of lactate in small animal clinical practice. Clin. Lab. Med.
2015
,35, 567–577.
[CrossRef] [PubMed]
28.
Garosi, L.S.; Dennis, R.; Platt, S.R.; Corletto, F.; de Lahunta, A.; Jakobs, C. Thiamine deficiency in a dog:
Clinical, clinicopathologic, and magnetic resonance imaging findings. J. Vet. Intern. Med.
2003
,17, 719–723.
[CrossRef] [PubMed]
29.
Penderis, J.; McConnell, J.F.; Calvin, J. Magnetic resonance imaging features of thiamine deficiency in a cat.
Vet. Rec. 2007,160, 270–272. [CrossRef] [PubMed]
30.
Falder, S.; Silla, R.; Phillips, M.; Rea, S.; Gurfinkel, R.; Baur, E.; Bartley, A.; Wood, F.M.; Fear, M.W. Thiamine
supplementation increases serum thiamine and reduces pyruvate and lactate levels in burn patients. Burns
2010,36, 261–269. [CrossRef] [PubMed]
31.
Elmadfa, I.; Majchrzak, D.; Rust, P.; Genser, D. The thiamine status of adult humans depends on carbohydrate
intake. Int. J. Vitam. Nutr. Res. 2001,71, 217–221. [CrossRef] [PubMed]
32.
Hanninen, S.A.; Darling, P.B.; Sole, M.J.; Barr, A.; Keith, M.E. The prevalence of thiamin deficiency in
hospitalized patients with congestive heart failure. J. Am. Coll. Cardiol.
2006
,47, 354–361. [CrossRef]
[PubMed]
Vet. Sci. 2017,4, 59 13 of 16
33.
Tasevska, N.; Runswick, S.A.; McTaggart, A.; Bingham, S.A. Twenty-four-hour urinary thiamine as a
biomarker for the assessment of thiamine intake. Eur. J. Clin. Nutr.
2008
,62, 1139–1147. [CrossRef] [PubMed]
34.
Baker, H.; Schor, S.M.; Murphy, B.D.; DeAngelis, B.; Feingold, S.; Frank, O. Blood vitamin and choline
concentrations in healthy domestic cats, dogs, and horses. Am. J. Vet. Res. 1986,47, 1468–1471. [PubMed]
35.
Read, D.H.; Jolly, R.D.; Alley, M.R. Polioencephalomalacia of dogs with thiamine deficiency. Vet. Pathol.
1977
,
14, 103–112. [CrossRef] [PubMed]
36.
Voigt, M.N.; Eitenmiller, R.R. Comparative review of the thiochrome, microbial and protozoan analyses of
B-vitamins. J. Food Prot. 1978,41, 730–738. [CrossRef]
37.
Talwar, D.; Davidson, H.; Cooney, J.; St JO’Reilly, D. Vitamin B(1) status assessed by direct measurement of
thiamin pyrophosphate in erythrocytes or whole blood by HPLC: Comparison with erythrocyte transketolase
activation assay. Clin. Chem. 2000,46, 704–710. [PubMed]
38.
Marks, S.L.; Lipsitz, D.; Vernau, K.M.; Dickinson, P.J.; Draper, W.; Larsen, J.A.; Fascetti, A.J. Reversible
encephalopathy secondary to thiamine deficiency in 3 cats ingesting commercial diets. J. Vet. Intern. Med.
2011,25, 949–953. [CrossRef] [PubMed]
39.
Tran, J.L.; Horvath, C.; Krammer, S.; Höller, U.; Zentek, J. Blood vitamin concentrations in privately owned
dogs fed non-standardized commercial diets and after intake of diets with specified vitamin concentrations.
J. Anim. Physiol. Anim. Nutr. 2007,91, 40–47. [CrossRef] [PubMed]
40.
Kritikos, G. Thiamine Concentrations in Extruded Dog and Cat Food & Determination of Thiamine Status in
Healthy Dogs and Cats and Comparison with Hospitalized Inappetent Animals. Master’s Thesis, University
of Guelph, Guelph, ON, Canada, 2017.
41.
Baines, M.; Davies, G. The evaluation of erythrocyte thiamin diphosphate as an indicator of thiamin status
in man, and its comparison with erythrocyte transketolase activity measurements. Ann. Clin. Biochem.
1988
,
25, 698–705. [CrossRef] [PubMed]
42.
Ihara, H.; Matsumoto, T.; Shino, Y.; Hashizume, N. Assay values for thiamine or thiamine phosphate esters
in whole blood do not depend on the anticoagulant used. J. Clin. Lab. Anal.
2005
,19, 205–208. [CrossRef]
[PubMed]
43.
Thornalley, P.J.; Babaei-Jadidi, R.; Al Ali, H.; Rabbani, N.; Antonysunil, A.; Larkin, J.; Ahmed, A.; Rayman, G.;
Bodmer, C.W. High prevalence of low plasma thiamine concentration in diabetes linked to a marker of
vascular disease. Diabetologia 2007,50, 2164–2170. [CrossRef] [PubMed]
44.
Abdou, E.; Hazell, A.S. Thiamine deficiency: An update of pathophysiologic mechanisms and future
therapeutic considerations. Neurochem. Res. 2015,40, 353–361. [CrossRef] [PubMed]
45. O’Keeffe, S.T. Thiamine deficiency in elderly people. Age Ageing 2000,29, 99–101. [CrossRef] [PubMed]
46.
Donnino, M.W.; Carney, E.; Cocchi, M.N.; Barbash, I.; Chase, M.; Joyce, N.; Chou, P.P.; Ngo, L. Thiamine
deficiency in critically ill patients with sepsis. J. Crit. Care 2010,25, 576–581. [CrossRef] [PubMed]
47.
Ahmed, M.; Azizi-Namini, P.; Yan, A.T.; Keith, M. Thiamin deficiency and heart failure: The current
knowledge and gaps in literature. Heart Fail. Rev. 2015,20, 1–11. [CrossRef] [PubMed]
48.
Manzanares, W.; Hardy, G. Thiamine supplementation in the critically ill. Curr. Opin. Clin. Nutr. Metab. Care
2011,14, 610–617. [CrossRef] [PubMed]
49.
Parr, J.M.; Remillard, R.L. Handling alternative dietary requests from dog owners. Vet. Clin. N. Am. Small
Anim. Pract. 2014,44, 667–688. [CrossRef] [PubMed]
50.
Remillard, R.L. Homemade diets: Attributes, pitfalls, and a call for action. Top. Companion Anim. Med.
2008
,
23, 137–142. [CrossRef] [PubMed]
51.
Stockman, J.; Fascetti, A.J.; Kass, P.H.; Larsen, J.A. Evaluation of recipes of home-prepared maintenance diets
for dogs. J. Am. Vet. Med. Assoc. 2013,242, 1500–1505. [CrossRef] [PubMed]
52.
Dillitzer, N.; Becker, N.; Kienzle, E. Intake of minerals, trace elements and vitamins in bone and raw food
rations in adult dogs. Br. J. Nutr. 2011,106, S53–S56. [CrossRef] [PubMed]
53.
Roudebush, P.; Cowell, C.S. Results of a hypoallergenic diet survey of veterinarians in North America with a
nutritional evaluation of homemade diet prescriptions. Vet. Dermatol. 1992,3, 23–28. [CrossRef]
54.
Heinze, C.R.; Gomez, F.C.; Freeman, L.M. Assessment of commercial diets and recipes for home-prepared
diets recommended for dogs with cancer. J. Am. Vet. Med. Assoc.
2012
,241, 1453–1460. [CrossRef] [PubMed]
55.
Larsen, J.A.; Parks, E.M.; Heinze, C.R.; Fascetti, A.J. Evaluation of recipes for home-prepared diets for dogs
and cats with chronic kidney disease. J. Am. Vet. Med. Assoc. 2012,240, 532–538. [CrossRef] [PubMed]
Vet. Sci. 2017,4, 59 14 of 16
56.
Freeman, L.M.; Michel, K.E. Evaluation of raw food diets for dogs. J. Am. Vet. Med. Assoc.
2001
,218, 705–709.
[CrossRef] [PubMed]
57.
Freeman, L.M.; Chandler, M.L.; Hamper, B.A.; Weeth, L.P. Current knowledge about the risks and benefits of
raw meat–based diets for dogs and cats. J. Am. Vet. Med. Assoc.
2013
,243, 1549–1558. [CrossRef] [PubMed]
58.
Michel, K.E. Unconventional diets for dogs and cats. Vet. Clin. N. Am. Small Anim. Pract.
2006
,36, 1269–1281.
[CrossRef] [PubMed]
59.
Oliveira, M.C.C.; Brunetto, M.A.; da Silva, F.L.; Jeremias, J.T.; Tortola, L.; Gomes, M.O.S.; Carciofi, A.C.
Evaluation of the owner’s perception in the use of homemade diets for the nutritional management of dogs.
J. Nutr. Sci. 2014,3. [CrossRef] [PubMed]
60.
Laflamme, D.P.; Abood, S.K.; Fascetti, A.J.; Fleeman, L.M.; Freeman, L.M.; Michel, K.E.; Bauer, C.;
Kemp, B.L.E.; Van Doren, J.R.; Willoughby, K.N. Pet feeding practices of dog and cat owners in the United
States and Australia. J. Am. Vet. Med. Assoc. 2008,232, 687–694. [CrossRef] [PubMed]
61.
Michel, K.E.; Willoughby, K.N.; Abood, S.K.; Fascetti, A.J.; Fleeman, L.M.; Freeman, L.M.; Laflamme, D.P.;
Bauer, C.; Kemp, B.L.; Van Doren, J.R. Attitudes of pet owners toward pet foods and feeding management of
cats and dogs. J. Am. Vet. Med. Assoc. 2008,233, 1699–1703. [CrossRef] [PubMed]
62.
Pachapurkar, D.; Bell, L.N. Kinetics of thiamin degradation in solutions under ambient storage conditions.
J. Food Sci. 2005,70, c423–c426. [CrossRef]
63.
Yang, P.-F.; Pratt, D.E. Antithiamin activity of polyphenolic antioxidants. J. Food Sci.
1984
,49, 489–492.
[CrossRef]
64.
Mulley, E.; Stumbo, C.; Hunting, W. Kinetics of thiamine degradation by heat. J. Food Sci.
1975
,40, 985–988.
[CrossRef]
65.
Arabshahi, A.; Lund, D. Thiamin stability in simulated intermediate moisture food. J. Food Sci.
1988
,53,
199–203. [CrossRef]
66.
Combs, G.F.J. Thiamin. In The Vitamins: Fundamental Aspects in Nutrition and Health, 3rd ed.; Combs, G.F.J.,
Ed.; Elsevier Academic Press: Cambridge, MA, USA, 2008; pp. 265–280.
67.
Coelho, M. Vitamin stability in premixes and feeds: A practical approach in ruminant diets. In Proceedings
of the 13th Annual Florida Ruminant Nutrition Symposium, Gainesville, FL, USA, 11–12 January 2002;
pp. 127–145.
68.
Awonorin, S.; Bamiro, F.; Ayoade, J. The effect of freezing rate, storage and cooking on some B-vitamins in
beef and pork roasts. Foodserv. Res. Int. 1996,9, 7–23. [CrossRef]
69.
Hall, K.; Lin, C. Effect of cooking rates in electric or microwave oven on cooking losses and retention of
thiamin in broilers. J. Food Sci. 1981,46, 1292–1293. [CrossRef]
70.
Korus, A.; Lisiewska, Z.; Kmiecik, W. Effect of freezing and canning on the content of selected vitamins and
pigments in seeds of two grass pea (Lathyrus sativus L.) cultivars at the not fully mature stage. Nahrung
2002
,
46, 233–237. [CrossRef]
71.
Słupski, J. Effect of freezing and canning on the thiamine and riboflavin content in immature seeds of five
cultivars of common bean (Phaseolus vulgaris L.). Int. J. Refrig. 2012,35, 890–896. [CrossRef]
72.
Hebrero, E.; Santos-Buelga, C.; Garcia-Moreno, C. Changes in thiamin content during the storage of spinach.
J. Agric. Food Chem. 1988,36, 144–147. [CrossRef]
73.
Beetner, G.; Tsao, T.; Frey, A.; Harper, J. Degradation of thiamine and riboflavin during extrusion processing.
J. Food Sci. 1974,39, 207–208. [CrossRef]
74.
Tran, Q.D.; Hendriks, W.H.; van der Poel, A.F. Effects of extrusion processing on nutrients in dry pet food.
J. Food Sci. Agric. 2008,88, 1487–1493. [CrossRef]
75.
U.S. Food and Drug Administration. Recalls, Market Withdrawals & Safety Alerts. Available online:
http://www.fda.gov/Safety/Recalls/ArchiveRecalls/default.htm (accessed on 22 February 2017).
76.
Food Standards Agency. Food Alerts News. Available online: https://www.food.gov.uk/news-updates/
news/food-alerts (accessed on 20 July 2017).
77. Weruva Updates. Available online: https://www.weruvaupdates.com/ (accessed on 20 July 2017).
78.
Markovich, J.E.; Freeman, L.M.; Heinze, C.R. Analysis of thiamine concentrations in commercial canned
foods formulated for cats. J. Am. Vet. Med. Assoc. 2014,244, 175–179. [CrossRef] [PubMed]
79.
Crane, S.W.; Cowell, C.S.; Stout, N.P.; Moser, E.A.; Millican, J.; Romano, P., Jr.; Crane, S.E. Commercial Pet
Foods. In Small Animal Clinical Nutrition, 5th ed.; Hand, M.S., Thatcher, C.D., Remillard, R.L., Roudebush, P.,
Novotny, B.J., Eds.; Mark Morris Institute: Topeka, KS, USA, 2010; pp. 157–190.
Vet. Sci. 2017,4, 59 15 of 16
80.
Costello, C.A.; Kelleher, N.L.; Abe, M.; McLafferty, F.W.; Begley, T.P. Mechanistic studies on thiaminase
I: Overexpression and identification of the active site nucleophile. J. Biol. Chem.
1996
,271, 3445–3452.
[CrossRef] [PubMed]
81.
Onozuka, M.; Konno, H.; Kawasaki, Y.; Akaji, K.; Nosaka, K. Involvement of thiaminase II encoded by the
THI20 gene in thiamin salvage of Saccharomyces cerevisiae.FEMS Yeast Res.
2008
,8, 266–275. [CrossRef]
[PubMed]
82.
Green, R.; Carlson, W.; Evans, C. The inactivation of vitamin B1 in diets containing whole fish. J. Nutr.
1942
,
23, 165–174.
83. Hilker, D.M.; Peter, O.F. Anti-thiamine activity in Hawaii fish. J. Nutr. 1966,89, 419–421. [PubMed]
84.
Gnaedinger, R.H.; Krzeczkowski, R.A. Heat inactivation of thiaminase in whole fish. Commer. Fish. Rev.
1966
,
28, 11–14.
85.
Vanier, N.L.; Paraginski, R.T.; Berrios, J.D.J.; Oliveira, L.d.C.; Elias, M.C. Thiamine content and technological
quality properties of parboiled rice treated with sodium bisulfite: Benefits and food safety risk. J. Food
Compos. Anal. 2015,41, 98–103. [CrossRef]
86.
U.S. Food and Drug Administration. Code of Federal Regulations Title 21. 21CFR182.3798. Available online:
https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/CFRSearch.cfm?fr=182.3798 (accessed on
7 July 2017).
87.
Berüter, J.; Somogyi, J.C. 3,4-Dihydroxycinnamic acid, an antithiamine factor of fern. Experientia
1967
,23,
996–997. [CrossRef] [PubMed]
88.
Bhattacharya, J.; Chaudhuri, D.K. Isolation and characterisation of a crystalline antithiamine factor from
mustard seed. Biochim. Biophys. Acta 1974,343, 211–214. [CrossRef]
89.
Rungruangsak, K.; Tosukhowong, P.; Panijpan, B.; Vimokesant, S.L. Chemical interactions between thiamin
and tannic acid. I. Kinetics, oxygen dependence and inhibition by ascorbic acid. Am. J. Clin. Nutr.
1977
,30,
1680–1685. [PubMed]
90.
Taungbodhitham, A.K. Thiamin content and activity of antithiamin factor in vegetables of Southern Thailand.
Food Chem. 1995,52, 285–288. [CrossRef]
91.
Yudkin, J. The vitamin B1 sparing action of fat and protein. 4. The effect of carbohydrate in diets deficient in
vitamin B1 upon the survival and vitamin B1 content of the rat. Biochem. J.
1951
,48, 608–611. [CrossRef]
[PubMed]
92.
Wilkinson, T.J.; Hanger, H.C.; George, P.M.; Sainsbury, R. Is thiamine deficiency in elderly people related to
age or co-morbidity? Age Ageing 2000,29, 111–116. [CrossRef] [PubMed]
93.
Jung, E.S.; Kwon, O.; Lee, S.H.; Lee, K.B.; Kim, J.H.; Yoon, S.H.; Kim, G.M.; Jeung, H.-C.; Rha, S.Y. Wernicke’s
encephalopathy in advanced gastric cancer. Cancer Res. Treat. 2010,42, 77–81. [CrossRef] [PubMed]
94.
Costantini, A.; Pala, M.I. Thiamine and fatigue in inflammatory bowel diseases: An open-label pilot study.
J. Altern. Complement. Med. 2013,19, 704–708. [CrossRef] [PubMed]
95.
Chapman, P.S. Vomiting and regurgitation. In Small Animal Critical Care Medicine, 1st ed.; Silverstein, D.,
Hopper, K., Eds.; Elsevier Inc.: St. Louis, MO, USA, 2009; pp. 570–574.
96.
Said, H.M. Intestinal absorption of water-soluble vitamins in health and disease. Biochem. J.
2011
,437,
357–372. [CrossRef] [PubMed]
97.
Mendoza, R.; Anderson, M.M.; Overbaugh, J. A putative thiamine transport protein is a receptor for feline
leukemia virus subgroup A. J. Virol. 2006,80, 3378–3385. [CrossRef] [PubMed]
98.
Mendoza, R.; Miller, A.D.; Overbaugh, J. Disruption of thiamine uptake and growth of cells by feline
leukemia virus subgroup A. J. Virol. 2013,87, 2412–2419. [CrossRef] [PubMed]
99.
Brenner, O.; Wakshlag, J.J.; Summers, B.A.; de Lahunta, A. Alaskan Husky encephalopathy—A canine
neurodegenerative disorder resembling subacute necrotizing encephalomyelopathy (Leigh syndrome).
Acta Neuropathol. 2000,100, 50–62. [CrossRef] [PubMed]
100.
Vernau, K.M.; Runstadler, J.A.; Brown, E.A.; Cameron, J.M.; Huson, H.J.; Higgins, R.J.; Ackerley, C.;
Sturges, B.K.; Dickinson, P.J.; Puschner, B.; et al. Genome-wide association analysis identifies a mutation in
the thiamine transporter 2 (SLC19A3) gene associated with Alaskan Husky encephalopathy. PLoS ONE
2013
,
8, e57195. [CrossRef] [PubMed]
101.
Swank, R.L.; Porter, R.R.; Yeomans, A. The production and study of cardiac failure in thiamin-deficient dogs.
Am. Heart J. 1941,22, 154–168. [CrossRef]
Vet. Sci. 2017,4, 59 16 of 16
102.
Bartges, J.W. Chronic kidney disease in dogs and cats. Vet. Clin. N. Am. Small Anim. Pract.
2012
,42, 669–692.
[CrossRef] [PubMed]
103.
Galler, A.; Tran, J.L.; Krammer-Lukas, S.; Höller, U.; Thalhammer, J.G.; Zentek, J.; Willmann, M. Blood
vitamin levels in dogs with chronic kidney disease. Vet. J. 2012,192, 226–231. [CrossRef] [PubMed]
104.
Lubetsky, A.; Winaver, J.; Seligmann, H.; Olchovsky, D.; Almog, S.; Halkin, H.; Ezra, D. Urinary thiamine
excretion in the rat: Effects of furosemide, other diuretics, and volume load. J. Lab. Clin. Med.
1999
,134,
232–237. [CrossRef]
105.
Markovich, J.E.; Heinze, C.R.; Freeman, L.M. Thiamine deficiency in dogs and cats. J. Am. Vet. Med. Assoc.
2013,243, 649–656. [CrossRef] [PubMed]
106.
Chang, Y.P.; Chiu, P.Y.; Lin, C.T.; Liu, I.H.; Liu, C.H. Outbreak of thiamine deficiency in cats associated with
the feeding of defective dry food. J. Feline Med. Surg. 2017,19, 336–343. [CrossRef] [PubMed]
107.
Everett, G.M. Observations on the behavior and neurophysiology of acute thiamin deficient cats.
Am. J. Physiol. 1944,141, 439–448.
108.
Irle, E.; Markowitsch, H.J. Thiamine deficiency in the cat leads to severe learning deficits and to widespread
neuroanatomical damage. Exp. Brain Res. 1982,48, 199–208. [CrossRef] [PubMed]
109.
Moon, S.J.; Kang, M.H.; Park, H.M. Clinical signs, MRI features, and outcomes of two cats with thiamine
deficiency secondary to diet change. J. Vet. Sci. 2013,14, 499–502. [CrossRef] [PubMed]
110.
Hackel, D.B.; Goodale, W.T.; Kleinerman, J. Effects of thiamin deficiency on myocardial metabolism in intact
dogs. Am. Heart J. 1953,46, 883–894. [CrossRef]
111. Davidson, M.G. Thiamin deficiency in a colony of cats. Vet. Rec. 1992,130, 94–97. [CrossRef] [PubMed]
112.
Negrin, A.; Cherubini, G.B.; Lamb, C.; Benigni, L.; Adams, V.; Platt, S. Clinical signs, magnetic resonance
imaging findings and outcome in 77 cats with vestibular disease: A retrospective study. J. Feline Med. Surg.
2010,12, 291–299. [CrossRef] [PubMed]
113.
Freeman, L.; Becvarova, I.; Cave, N.; MacKay, C.; Nguyen, P.; Rama, B.; Takashima, G.; Tiffin, R.; Tsjimoto, H.;
van Beukelen, P. WSAVA Nutritional Assessment Guidelines. J. Small Anim. Pract.
2011
,52, 385–396.
[CrossRef] [PubMed]
114.
Read, D.; Harrington, D. Experimentally induced thiamine deficiency in beagle dogs: Clinical observations.
Am. J. Vet. Res. 1981,42, 984–991. [PubMed]
115.
Saker, K.E.; Remillard, R.L. Critical Care Nutrition and Enteral-Assisted Feeding. In Small Animal Clinical
Nutrition, 5th ed.; Hand, M.S., Thatcher, C.D., Remillard, R.L., Roudebush, P., Novotny, B.J., Eds.; Mark
Morris Institute: Topeka, KS, USA, 2010; pp. 439–476.
116.
Prantil, L.R.; Markovich, J.E.; Heinze, C.R.; Linder, D.E.; Tams, T.R.; Freeman, L.M. Nutritional analysis
and microbiological evaluation of commercially available enteral diets for cats. J. Vet. Emerg. Crit. Care
(San Antonio) 2016,26, 254–261. [CrossRef] [PubMed]
117. Da Silva, A.; Ivy, A. Absorption of thiamine from intestine of dog. Am. J. Physiol. 1961,201, 185–189.
118.
Di Palma, J.R.; Hitchcock, P. Neuromuscular and ganglionic blocking action of thiamine and its derivatives.
Anesthesiology 1958,19, 762–769. [CrossRef] [PubMed]
119.
Cruickshank, A.M.; Telfer, A.B.; Shenkin, A. Thiamine deficiency in the critically ill. Intensiv. Care Med.
1988
,
14, 384–387. [CrossRef]
120.
Stephen, J.M.; Grant, R.; Yeh, C.S. Anaphylaxis from administration of intravenous thiamine. Am. J.
Emerg. Med. 1992,10, 61–63. [CrossRef]
©
2017 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access
article distributed under the terms and conditions of the Creative Commons Attribution
(CC BY) license (http://creativecommons.org/licenses/by/4.0/).
