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Canine Pyometra: An
Update on Pathogenesis
and Treatment
Washington State University–Pullman
Boel A. Fransson, DVM, MS
Claude A. Ragle, DVM, DACVS, DABVP
ABSTRACT: Despite six decades of research, the pathogenesis of pyometra is still not com-
pletely understood. Recent investigations question whether the previous concept of consider-
ing cystic endometrial hyperplasia (CEH)–pyometra as a complex is correct. The pathogenesis
of CEH appears to have a strong hormonal component, whereas the etiology of pyometra
might be moreinfluenced by the bacterial component. However,CEH may predispose bitches
to develop pyometra. Critically ill pyometra patients should be monitored for clinical criteria of
systemic inflammatory response syndrome. Closed-suction abdominal drains and a different
administration route for prostaglandin F2αare promising enhancements in the treatment of
pyometra.
Canine pyometra is a disease syndrome that affects adult intact bitches,
causing a variety of clinical and pathologic signs of genital and systemic
disease. The pathogenesis of canine pyometra is not completely under-
stood, despite decades of studies concerning the etiology of the disease. The con-
cept of cystic endometrial hyperplasia (CEH)–pyometra, introduced by Dow,1
states that hormonal changes lead to CEH (Figure 1) and render the uterus sus-
ceptible to secondary infection, which leads to pyometra (Figure 2). Recently, it
has been suggested that the classic CEH–pyometra complex description should
be separated into two entities: CEH and pyometra. CEH may predispose for
pyometra in some cases, but pyometra can also occur without CEH. Mounting
evidence suggests that the development of pyometra is an entity separate from
CEH, with a hormonal component in the pathogenesis but mainly triggered by
bacterial infection.2
ETIOLOGY—THE HORMONAL COMPONENT
The investigated factors of pathogenesis in CEH and pyometra are summa-
rized in Figure 3.
■Canine pyometra is not always
secondary to cystic endometrial
hyperplasia, and the two
disorders might have different
pathogeneses.
■In generalized septic peritonitis
from a ruptured uterus, closed-
suction drainage can be an
alternative to open abdominal
drainage.
■Prostaglandin F2αadministered
intravaginally has shown
promising results with good
efficacy and fewer side effects
than when administered
subcutaneously.
www.VetLearn.com
602 Vol. 25, No. 8 August 2003
Article #3 (1.5 contact hours)
Refereed Peer Review
KEY FACTS
CE
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Figure 1—The endometrium in a dog with CEH. CEH is
most likely due to an exaggerated uterine response to proges-
terone and estrogen.
Figure 2—A severely pus-distended uterus with pyometra.
The pathogenesis of pyometra may be mainly triggered by
infection.
Hormone Production
Progesterone has been shown to stimulate endome-
trial glandular secretion and to suppress contractions of
the uterus, thus creating an intrauterine environment
predisposed to bacterial growth.3The importance of
hormonal influence on the uterus in the pathogenesis
of pyometra was suspected in early research, based on
the observation that the disease most commonly occurs
during progesterone influence in diestrus. After con-
cluding that few bacteria were virulent enough to be
the sole cause of pyometra, Teunissen4found that the
cystic and inflammatory changes of the uterine wall
associated with pyometra (but not the abundant pus
production) could be reproduced by injections of pro-
gesterone. Estrogen alone seemed to play a less impor-
tant role but appeared to enhance the endometrial
response to progesterone.
Several authors have investigated whether prolonged
or excessive progesterone production could be responsi-
ble for the development of pyometra but failed to
measure such alterations.5,6
Hormone Receptors
More recent investigations have evaluated whether
upregulation of endometrial hormone receptors that
leads to an exaggerated response to progesterone, estro-
gen, or androgen is responsible for the development of
the disease.2,7,8 Expression of estrogen and progesterone
receptors has been shown to be elevated in uteri of
bitches with CEH but not in uteri of bitches with
pyometra. It also was noted that CEH and pyometra
often occur independently, and the research group has
suggested that the findings indicate different patho-
geneses of these two conditions.2At present there is no
conclusive evidence that pyometra is caused by a distur-
bance either in hormone production or in the uterine
response to these hormones. Future researchers may
need to approach CEH–pyometra with an open mind
and investigate new topics, such as bacterial interaction
with the uterus during the different stages in the
estrous cycle.
Such considerations as a possible different pathogenesis
and other major differences between CEH and pyometra
(e.g., lack of a bacterial component, different blood bio-
chemistry findings9) may indicate that it is time to divide
the CEH–pyometra complex into two entities.
ETIOLOGY—THE BACTERIOLOGIC COMPONENT
Past investigations of the bacteria associated with
canine pyometra have been few. However, it has been
well established that the most common infecting agent
is Escherichia coli (Figure 4), which is isolated in 59%
to 96% of pyometra cases. Occasionally, other agents
(e.g., Klebsiella organisms, streptococci, staphylococci,
anaerobic bacteria, pseudomonads) are isolated from
the uterus of an infected animal.9–12 Sandholm and
coworkers11 found that E. coli demonstrated adherence
to receptors in progesterone-stimulated endometrium,
which is one explanation for the observed predomi-
nance of this bacterium.
Virulence Factors
Certain serotypes of E. coli, such as 02, 04, 06,
075,10,11 and 032,12 appear to be isolated more com-
monly than other serotypes from dogs with pyometra.
However, the virulence factors of these serotypes have
been sparsely investigated. The presence of a K antigen,
an important virulence factor of E. coli –inducing cysti-
tis, has been demonstrated in dogs with pyometra as
well.11,12 The virulence factor, cytotoxin necrotizing fac-
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tor, was expressed in seven of 16 serotypes associated
with pyometra, and the presence of this factor was
related to more severe endometrial changes.12
Infection Route
The route of infection was once considered to be
hematogenic as well as ascending.1Our research group
performed bacterial epidemiologic studies of E. coli iso-
lates from pyometra using biochemical fingerprinting, a
method that has proved to be highly discriminative
between clones of bacteria of the same species.13 We
found a fecal strain of E. coli identical to the correspond-
ing uterine isolate in each of 10 bitches with pyometra.
Thus an ascending route of infection from the fecal
flora into the uterus is the most logical explanation in
those cases of pyometra.14
Cystitis has been shown to be commonly associated
with canine pyometra.11,14,15 The E. coli bacteria isolated
from the urinary bladder and the isolate from the
uterus are descendents of the same clone of bacteria, as
evidenced by biochemical fingerprinting and by restric-
tion enzyme digestion and pulsed-field gel elec-
trophoresis.14,16 Sandholm and coworkers11 have sug-
gested that the urinary tract may serve as a bacterial
reservoir and that bacteria ascend into the uterus dur-
ing a susceptible stage in the estrous cycle. Another
explanation for this phenomenon is that during
pyometra, bacteria in the purulent vaginal discharge
Systemic circulation
Hormones:
Progesterone
Estrogen
Androgen
Unidentified hormones?
Bacterial products and components:
• Endotoxin
• Unidentified toxins?
Affects the animal and the uterus
Effects:
• Stimulation of glands
• Modifications of
uterine motility
Bacteria
Bacterial receptors
Hormone
receptor numbers
Endometrium with glands
Myometrium
Systemic effects:
• Renal dysfunction
• Immunosuppression
• Decreased survival
• SIRS?
Bacterial virulence
factors:
• K antigen
• CNF
• Unidentified
virulence factors?
Figure 3—An illustration of the hormonal and bacteriologic components in the pathogenesis of pyometra that have been investi-
gated. Areas previously investigated include peripheral hormone levels (progesterone, estrogen, androgen), number of hormone
receptors in the endometrium, the different hormonal effects on the endometrium, presence of bacterial receptors in the
endometrium, the effects of bacterial products and components on the uterus or on the animal, bacterial virulence factors in
pyometra, and systemic effects of pyometra. Question marks indicate important areas for future research. (CNF = cytotoxin necro-
tizing factor)
Compendium August 2003 Canine Pyometra 605
can easily ascend the urinary tract, especially because
the urethra opening in bitches is in an anatomically
dependent position.
SYSTEMIC EFFECTS OF PYOMETRA
The clinical signs of pyometra are not limited to the
genital tract. The most frequently reported clinical signs
include anorexia, vomiting, polydipsia and polyuria,
lethargy, and vulvar discharge.1,9,15,17,18 The clinical signs
are often more severe in dogs when the cervical canal is
occluded, and these dogs frequently have a distended
abdomen and severe lethargy. However, the cervix may
spontaneously open or close during the disease, causing
intermittent vaginal discharge or a sudden deterioration
in the clinical status of the bitch.1,18
Systemic Inflammatory Response Syndrome
Canine pyometra is often associated with systemic
inflammatory response syndrome (SIRS).19 This syn-
drome is associated with any serious infectious, inflam-
matory, traumatic, or neoplastic foci that cause produc-
tion and release of inflammatory mediators that affect
the body systemically. SIRS is the common name for
what previously was called sepsis, septic syndrome, or
septic shock.19 SIRS is identified clinically in dogs by
the presence of two of four criteria, including heart rate
(>160 bpm), temperature (>103.5°F or <100°F), respi-
ratory rate (>20 breaths/min or partial pressure of car-
bon dioxide <32 mm Hg), and white blood cell count
(>12,000/µl, <4,000/µl, or >10% band neutrophils).20
To decrease the risk for overlooking a patient that is
developing SIRS, it has been suggested that these crite-
ria include a heart rate over 120 bpm; a temperature
Figure 4—E. coli is the bacteria most commonly isolated from
uteri of patients with pyometra. CEH is not associated with
infection.
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below 100.6°F or over 102.6°F; and white blood cell
counts of over 16,000/µl, less than 6,000/µl, or less
than 3% band neutrophils.21 However, use of the latter
criteria is associated with a high risk for overdiagnosing
SIRS. Until specific markers for SIRS in dogs are devel-
oped, clinicians should use their clinical judgment in
the evaluation of the individual pyometra patient, with
the SIRS criteria serving as guidelines for monitoring
the animal.
Endotoxemia and Systemic Effects
Lipopolysaccharide, or endotoxin, is a cell wall com-
ponent of E. coli and other gram-negative bacteria and
can be released either as a result of bacterial death and
disruption or during vigorous growth of the bacteria.22
Experimentally, sublethal doses of endotoxin have been
shown to cause fever, lethargy, and increases in heart
and respiratory rates. Higher doses in dogs give rise to
cardiovascular and gastrointestinal effects, such as
mucoid, bloody diarrhea and vomiting. The hemody-
namic changes are initially transient if compensated by
adequate support and treatment. If the hemodynamic
changes are uncompensated, endotoxic shock often
leads to myocardial failure and death.23 The outcome in
canine pyometra has been shown to relate to blood
endotoxin concentration in which high plasma endo-
toxin concentration was associated with mortality.24
Severity of clinical signs has also been related to the
degree of immunosuppression in dogs with pyometra.25
Endotoxemia is a possible cause of impaired lymphocyte
activity, one of the features of immunosuppression seen
in canine pyometra.25 However, the evidence for endo-
toxemia in bitches with pyometra conflicts. Studies con-
ducted by our research group did not reveal endotox-
emia in 50 of 53 cases, but these dogs were all in good
general health,9which is in accordance with a previous
study.26 Experimentally induced endotoxemia in dogs is
associated with severe clinical signs, such as cardiovascu-
lar depression or collapse, and persistent endotoxemia
should be expected mainly in critically ill dogs.
Endotoxemia and Polyuria
Polyuria and polydipsia are common features of
pyometra, a fact that has intrigued many investigators.
IV injection of killed E. coli was shown to induce a
reversible reduction in renal concentrating ability. The
dysfunction was not associated with decreased release of
antidiuretic hormone (ADH) and could not be reversed
with exogenous ADH administration.27 Therefore, this
effect is likely a result of decreased renal response to
ADH, but the exact mechanism is unknown. Later work
has found evidence of both glomerular dysfunction and
renal tubular damage associated with pyometra.28,29 The
classical polyuria and polydipsia seen in canine pyometra
are probably of multifactorial origin (i.e., decreased
response to ADH, glomerular dysfunction, renal tubular
cell damage). In general, polyuria is reversible after ovari-
ohysterectomy and is most likely a result of bacterial
Table 1. Common Laboratory Parameter Abnormalities in Bitches with Pyometra
Parameter Clinical Abnormality Grade
White blood cell count Leukocytosis Moderate to severe1,9,11,33
Left shift Moderate to severe1,9,11,33
Hemoglobin Anemia Mild9,30–32
Packed cell volume Anemia Mild9,30–32
Serum
Alanine aminotransferase Normal or decreased Mild to moderate9,30,32
Albumin Hypoalbuminemia Mild to moderate9,30–32
Alkaline phosphatase Increased Mild9,30–32
Aspartate aminotransferase Increased Mild9,30–32
Bilirubin Bilirubinemia Mild9,30–32
Blood urea nitrogen Increased in 15%–21% of cases Mild to moderate28,31
Cholesterol Hypercholesterolemia Mild9,30–32
Creatine kinase Increased Mild to moderate30
Creatinine Increased in 17%–31% of cases Mild to moderate28,31
Globulin Hyperglobulinemia Mild to moderate9,30–32
Lactate dehydrogenase Increased Mild9,30–32
Urine
Protein Proteinuria Mild to moderate28,30
Sediment Bacteriuria >104/µl9,11,15
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components, such as endotoxin, or bacterial products
gaining access to the systemic circulation.
COMMON LABORATORY PARAMETER
ABNORMALITIES
The systemic effects of pyometra are reflected by sev-
eral laboratory parameters (Table 1). Anemia in typical
cases is caused by reduced production of erythrocytes
resulting from the systemic inflammatory response.
Hyperglobulinemia is a result of inflammation and
hypoalbuminemia, which is considered part of an acute
phase reaction.30 Elevated levels of alkaline phosphatase,
bilirubin, and serum cholesterol are considered to result
from intrahepatic cholestasis rather than from hepatocyte
damage.9,31 This is in accordance with the observed low
activity of alanine aminotransferase,9,30,32 which indicates
that hepatocellular necrosis has not occurred. Examina-
tion of liver biopsy specimens confirmed these interpre-
tations because fatty infiltration and bile pigments, but
no gross hepatocellular necrosis, were observed.31
TREATMENT
Surgical Options
Ovariohysterectomy, the treatment of choice in most
cases of pyometra, generally results in a rapid recovery
with minimal risk for recurrence and also negates the
risk for ovarian or uterine neoplasia or unwanted preg-
nancy. Reported complications of surgery include anes-
Figure 5—An example of a closed-suction drain system. After
insertion in the wound or the abdominal cavity, the bulb
reservoir is deflated, which will cause negative pressure to suc-
tion out air and drain fluid. A port separate from the drain
connection port allows easy emptying and deflation.
“Rule of 20”—Parameters to Monitor
in Patients with SIRS20
1. Fluid balance
2. Blood pressure/perfusion
3. Cardiac function
4. Albumin
5. Oncotic pull
6. Oxygenation/ventilation
7. Glucose
8. Electrolyte/acid–base balance
9. Mentation
10. Coagulation
11. Packed cell volume
12. Renal function/urine output
13. White blood cell count/antibiotic therapy
14. Gastrointestinal motility/integrity
15. Drug metabolism/doses
16. Nutrition
17. Pain control
18. Nursing mobility/catheter care
19. Bandage/wound care
20. Tender loving care
thetic complications, hemorrhage, peritonitis, incom-
plete removal of the ovaries, wound swelling, wound
infection, and fistulous tracts.33 Surgical and anesthetic
complications can be decreased if severely ill bitches
receive appropriate therapy to stabilize their condition
before surgery. Postsurgical mortality in bitches with
pyometra has been found to be approximately 5%.33
Preoperative stabilization of a bitch with pyometra
must be tailored to the findings of physical examina-
tion and laboratory results. In Scandinavia, dogs are
not routinely spayed and neutered, and the prevalence
of pyometra is very high. Recently published data from
an epidemiologic study of approximately 200,000 dogs
covered by insurance in Sweden have shown that
approximately 1,800 bitches were treated for pyometra
in 1996. According to these data, the risk of an intact
bitch to develop pyometra before 10 years of age is
23% to 24%.34 The author’s experience (B. A. F.) as a
surgeon at the Swedish University of Agricultural Sci-
ence has included treating 210 cases of pyometra. Sub-
jectively, signs of severe systemic illness were noted in
few of these bitches. The routine preoperative stabiliza-
tion of bitches with uncomplicated pyometra mainly
included rehydration by IV infusion of a balanced elec-
trolyte solution (acetated Ringer’s solution). Routine
anesthetic premedication included acepromazine (0.03
to 0.05 mg/kg IV) and buprenorphine (0.005 to 0.01
mg/kg IV); for anesthesia, induction was most com-
monly accomplished with thiopental (5 to 15 mg/kg
IV) and maintained with isoflurane inhalation. Antibi-
otic therapy was not used unless signs of systemic ill-
ness were present. The author (B. A. F.) currently rec-
ommends the use of IV broad-spectrum antibiotics at
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the time of induction to counteract possible bacteremia
from manipulation of the uterus; the dose should be
repeated if the operation lasts more than 90 minutes.
These guidelines represent the standard perioperative
antibiotic use at our hospital and were originally based
on the prevention of postoperative infection in dogs
after orthopedic procedures.35 Antibiotic therapy
should be continued after surgery in systemically ill
dogs or in dogs with increased risk of complications. In
pyometra cases with physical examination or laboratory
findings consistent with SIRS, it is wise to proceed
more cautiously before the surgical procedure. Pre- and
postoperative therapy and monitoring are performed
according to the “Rule of 20” (see box on page 607).20
Anesthesia and ovariohysterectomy should be per-
formed without delay when cardiovascular parameters
are as stable as possible. In these patients, induction
with a combination of diazepam and oxymorphone
(0.5 mg/kg and 0.1 to 0.2 mg/kg, respectively, adminis-
tered alternately) or diazepam and ketamine (mixture
of 0.5 mg/kg diazepam and 10 mg/kg ketamine, given
to effect) might cause less severe cardiovascular side
effects than thiopental.
The recommended surgical technique has been
described previously.36,37 Compared with the regular
spay, the incision is extended and the surgeon must
manipulate the pus-distended and often friable uterus
with extreme care to avoid penetration. The uterus
should be packed off with laparotomy sponges before
manipulation and transsection. The suspensory liga-
ment is often stretched from the weight of the uterus
and generally does not require strumming. The vessels
in the broad ligaments might be enlarged due to the
uterine inflammation and need to be ligated with 2-0 or
0 monofilament absorbable suture. Because triple
Table 2. Selection Criteria for Ideal Candidates for Medical Management with PGF2α
α
Candidate Feature Rationale
Patient has a highly motivated owner who is informed Side effects, such as anxiety, hypersalivation, panting,
about side effects and is willing to hospitalize the pet vomiting, abdominal pain, tachycardia, and fever
if it is at risk are common and can be dramatic; however, they
usually resolve within 1 hr after treatment.39
High breeding value; owners want to breed the bitch The long-term outcome of medical management
within the next estrous cycle has been associated with recurrence in most of the
dogs treated with PGF2α.43
Patient is not systemically ill There is a 48-hr lag before effects of treatment can
be seen, and clinical deterioration can occur in the
meantime. Bacteremia can occur from therapy.42
Patient has an open cervix as evidenced by vaginal Two cases described in the literature of uterine
discharge rupture or peritonitis after PGF2αtreatment of
bitches with closed-cervix pyometra.42,48
Figure 6—An alternative treatment of pyometra refractory to
PGF2α. Schematic drawing shows transvaginally placed
intrauterine catheters with the tip of the catheters positioned
5 to 10 cm cranial to the bifurcation. The inset shows a tech-
nique of fixing the catheters to the dorsal wall of the vagina
by ligatures of 3-0 stainless steel. These drains are inserted
with the aid of a specifically designed guiding device and
fluoroscopy. (From Lagerstedt A-S, Obel N, Stavenborn N,
et al: Uterine drainage in the bitch for treatment of pyometra
refractory to prostaglandin F2α.J Small Anim Pract 28:215–
222, 1987; with permission)
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clamping of the uterine body can result in uterine lacer-
ation in a friable uterus, nontraumatic forceps (e.g.,
Doyen) are recommended to avoid an abundance of pus
at the intended ligation site. To avoid leaving compro-
mised tissue and foreign material (suture) in an infected
site, the uterine stump should not be oversewed.36
In patients with severe generalized peritonitis, copi-
ous abdominal lavage with warm saline is recom-
mended. Thereafter, the surgeon must decide whether
additional abdominal drainage is indicated. If drainage
is deemed necessary, two options are available: open
abdominal drainage or closed-suction drain systems.
Traditionally, open abdominal drainage has been rec-
ommended because it allows efficient drainage of the
abdominal cavity. However, the method is labor-inten-
sive and requires daily bandage changes (preferably per-
formed with the patient under general anesthesia in a
surgical suite using aseptic technique).38 The use of
closed-suction drain systems for generalized peritonitis
has recently been reviewed.39 A new generation of these
drains (Figure 5) has overcome the problem of drain
obstruction from fibrin and adhesions, which is the
limiting factor for closed abdominal drainage.39 There
are no apparent differences in survival between these
two methods, with 71% survival of open peritoneal
drainage38 versus 70% with closed-suction drainage.39
Laparoscopic surgery has been performed for pyometra
in dogs40 and in horses by one of the authors (C. A. R.).
Medical Management
Case selection criteria for treatment of dogs with
pyometra with SC injections of prostaglandin F2α
(PGF2α) are listed in Table 2. PGF2αcauses contraction
of the myometrium and relaxation of the cervical
canal,41 which leads to expulsion of exudate from the
uterine lumen. Response to treatment consists of a
decrease in uterine diameter, cessation of uterine dis-
charge, and return of a normal leukogram.42,43 The side
effects associated with PGF2αinclude abdominal pain,
emesis, defecation, tachycardia, hypersalivation, dys-
pnea, panting, and fever.17 A low-dosage treatment
(0.025 mg/kg injected SC q12h for 5 days or to effect)
of a natural PGF2α, such as dinoprost tromethamine,
has been shown to be effective44 and is associated with
fewer side effects than with higher doses.17 A systemic
bactericidal antibiotic should be administered concomi-
tantly with PGF2αto prevent bacteremia,42 and the
antibiotic treatment should be continued for 10 to 14
days. Amoxicillin (10 to 20 mg/kg PO or SC q8–12h)
seems to be a reasonable choice in uncomplicated cases;
however, if the bitch shows fever or an affected attitude,
enrofloxacin (2.5 to 5 mg/kg IV or PO bid or 10
mg/kg sid) or gentamicin (2.2 mg/kg IV or SC q8h)
may be considered.45 If gentamicin is used, adequate
hydration must be maintained.
Intravaginal administration of PGF2αwas recently
reported to be successful in 13 of 15 bitches with
pyometra. No side effects were observed after this
administration route was used; however, this route is not
approved in dogs and is considered experimental. A nat-
ural PGF2α(such as dinoprost tromethamine) at a dose
of 0.15 mg/kg (0.3 ml/10 kg) was infused vaginally
using a sterile plastic catheter. Immediately after infu-
sion, the hindquarters of the animal were raised for 3 to
5 minutes to prevent loss of the infused substance.45
Recurrence was not noted within the 12 months follow-
ing treatment.45
Treatment with the antiprogestin RU 46534 in
bitches with pyometra has been associated with clinical
recovery and successful posttreatment breeding results
in two of six dogs in a preliminary clinical study.46
Antiprogestin promotes expulsion of uterine contents
by myometrial contraction in cases in which the pre-
treatment plasma progesterone concentrations are
higher than 2 mg/ml. The bitches in the preliminary
study were followed up only to the next estrous cycle,
and the recovery rate was not evaluated.46 The antipro-
gestin RU 46534 is, to the authors’ knowledge, not
commercially available.
In cases refractory to PGF2αtherapy or with a closed
cervix, drainage has been performed by using catheters
placed into the uterine lumen through the vagina (Fig-
ure 6). A technique requiring a specific guiding device
showed a good outcome in nine of 12 bitches, with five
of six bred bitches conceiving47 (Figure 7). A newer
Figure 7—Schematic drawing showing a guiding device
specifically designed for transvaginal catheterization of the
canine uterus. (A) The device is inserted as far cranially as
possible into the ventral fornix of the ventrally tilted canine
cervix. (B) As the device is slightly retracted, the cervix is
lifted into alignment with the cannula, enabling catheteriza-
tion. (From Lagerstedt A-S, Obel N: Uterine cannulation in
the bitch. J Vet Med A Physiol Pathol Clin Med 34:90–101,
1987; with permission)
A
B
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technique for transcervical uterine cannulation has been
described that uses a hysteroscope, a rigid endoscope
25-cm long designed for use in women.48 Air is insuf-
flated into the vagina through a channel in the operat-
ing sheath of the endoscope, and the cervix is visualized
to allow introduction of a size 4 to 7 Fr (1.35 to 2.3
mm) catheter.48 However, the latter technique has not
been described at present for introduction of catheters
for draining purposes in pyometra cases.
CONCLUSION
Despite over six decades of canine pyometra studies,
the etiology of the disease is still unclear. The hormonal
component of the etiology has been extensively investi-
gated. Recently, it has been suggested that the role of the
infecting bacteria potentially could be more important
than previously believed, both in the determination of
the systemic response to pyometra and in initiation of
the disease. The bacterial component in the pathogene-
sis of pyometra is important for the development of a
systemic inflammatory response. The inflammatory
response to bacterial components is suspected to cause
decreased survival and immunosuppression in dogs with
pyometra. Information regarding virulence factors of the
bacteria associated with canine pyometra is minimal,
and it seems imperative to direct future studies to this
area. Surgery remains the treatment of choice in canine
pyometra, and the management of patients with com-
plicated pyometra has been enhanced by the develop-
ment of new products for abdominal drainage. The
development of criteria for SIRS in small animals pro-
vides guidelines for monitoring and treating critically ill
patients with pyometra. New treatment alternatives for
the medical management of pyometra in animals with
high breeding value include intravaginal administration
of PGF2α, administration of antiprogestin RU 46534,
and drainage of the uterus, which has been enhanced by
new techniques for transcervical uterine cannulation.
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1. Which bacterium is most commonly isolated from the
uterus in canine pyometra?
a. E. coli
b. Klebsiella spp
c. Staphylococcus intermedius
d. Streptococcus canis
e. anaerobic species
2. Which hormonal abnormalities have been shown to
induce pyometra?
a. upregulation of endometrial androgen receptors
b. prolonged or excessive endogenous progesterone
production
c. upregulation of endometrial progesterone receptors
d. upregulation of endometrial estrogen receptors
e. none of the above
3. What stimulus is required for the endometrium to
develop receptors to which bacteria adhere?
a. estrogen
b. progesterone
c. androgen
d. cortisol
e. thyroxin
4. Which serotype of E. coli has not been commonly
associated with canine pyometra?
a. 02 d. 08
b.04 e. 032
c. 06
5. Which is the most likely origin of the bacteria that
infect the uterus?
a. oral flora from licking the vulva
b.pathogenic bacteria in the environment
c. pathogenic bacteria from direct genital contact with
another dog
d. infectious bacteria transmitted between bitches in
the same household
e. ascending fecal flora from the bitch herself
CE
ARTICLE #3 CE TEST
The article you have read qualifies for 1.5 con-
tact hours of Continuing Education Credit from
the Auburn University College of Veterinary Med-
icine. Choose the best answer to each of the follow-
ing questions; then mark your answers on the
postage-paid envelope inserted in Compendium.
6. Which concomitant infection is commonly associated
with pyometra?
a. external otitis
b. lower urinary tract infection
c. upper urinary tract infection
d. bacterial enteritis
e. none of the above
7. Which is not identified as a criterion of SIRS?
a. capillary refill time
b. heart rate
c. respiratory rate
d. temperature
e. white blood cell count
8. Endotoxemia in bitches with pyometra has been asso-
ciated with
a. poor survival.
b. length of hospitalization.
c. a high cost of treatment.
d. disseminated intravascular coagulation.
e. leukopenia.
9. Which is the most characteristic blood work abnor-
mality in pyometra?
a. decreased packed cell volume
b. leukocytosis
c. hypoalbuminemia
d. increase in alkaline phosphatase
e. decrease in alanine aminotransferase
10. Which agent has been used in the management of
pyometra?
a. broad-spectrum antibiotics
b. SC injection of PGF2α
c. intravaginal administration of PGF2α
d. antiprogestin RU 46534
e. all of the above
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