Canine Pyometra (Dog breeders worst nightmare)

Canine pyometra: Early recognition and diagnosis
Although this uterine disorder typically affects adult dogs, it can occur in intact female dogs of any age. Because of its nonspecific clinical signs, it may be overlooked until severe. Here's what you need to know to identify pyometra as early as possible.
Canine pyometra is an infectious and inflammatory disorder of the uterus typically occurring in adult, intact bitches during or immediately after the luteal phase of the estrous cycle. The clinical signs of pyometra are often nonspecific and vary among patients depending on the chronicity of the disease and the patency of the cervical canal. Early recognition, diagnosis, and treatment of pyometra are necessary to achieve a successful outcome.
In this article, we review the pathophysiology, signalment, clinical signs, and diagnosis of canine pyometra..
PATHOGENESIS
The physiologic changes responsible for predisposing a uterus to pyometra are not completely understood. The vagina is not a sterile environment. Many bacteria types have been cultured from the normal vaginal vault, including Escherichia coli and Staphylococcus, Streptococcus, Klebsiella, Pasteurella, Pseudomonas, and Proteus species. These same bacteria are commonly cultured from the uteri of patients with pyometra, which suggests that bacteria ascending from the dog's vaginal vault are the likely source of uterine infection in most patients developing pyometra. In a study of 10 dogs with pyometra, the bacteria isolated from the uterus were genetically similar to those found in the patients' gastrointestinal tracts, demonstrating that bacteria within a patient's own body—and not exogenous bacteria—are responsible for infection. Primary urinary tract infections and the hematogenous spread of bacteria from nongenitourinary sites have been suggested to be less frequent sources of infection than ascending infections from the vagina.
However, bacterial contamination of the uterus does not appear to be solely responsible for the development of pyometra. Vaginal bacteria will normally cross the cervix into the uterus when the cervix is open (proestrus and estrus), yet pyometra does not routinely develop. Other uterine factors are thought to predispose the uterus to progressive infection.
Studies performed in the 1950s suggested that cystic endometrial hyperplasia is a prerequisite for the development of pyometra in a bitch. Cystic endometrial hyperplasia develops in most intact female dogs as they age. It is caused by chronic recurrent exposure of the endometrial lining to progesterone produced by the corpus luteum during diestrus. Binding to uterine receptors, progesterone induces endometrial gland proliferation, stimulates endometrial gland secretions, decreases myometrial contractility, and induces closure of the cervix. Progesterone has also been shown to interfere with immune function within the uterus, possibly increasing its susceptibility to bacterial infection. Progesterone's effect on the endometrium is cumulative from reproductive cycle to reproductive cycle.
The studies suggested that accumulating uterine secretions, prominent endometrial gland crypts, and immunosuppression caused by progesterone stimulation during diestrus make the uterus an ideal environment for bacterial proliferation leading to pyometra. This condition has been subsequently termed cystic endometrial hyperplasia-pyometra complex.
Not all dogs with pyometra have cystic endometrial hyperplasia. Other factors can play a role in the development of pyometra. Studies have demonstrated that irritants within the uterus, such as foreign material that has passed through the cervix or even a subclinical bacterial infection, may induce endometrial inflammation and hyperplasia. These endometrial changes contribute to a favorable environment for bacterial colonization or proliferation, leading to pyometra. The propensity of some pathogenic bacteria, such as E. coli, to attach to the endometrium may explain why some bitches without cystic endometrial hyperplasia develop pyometra. Exogenous hormones can also prime the uterus for infection. Pyometra has been noted to occur after the exogenous administration of estrogen used to inhibit pregnancy after a mismating. Exogenous estrogen enhances the uterus's sensitivity to endogenous progesterone.
The sequence of pathophysiologic events leading to pyometra varies among bitches and continues to be studied. A consistent factor in the development of pyometra is the presence of a progesterone-primed uterus.
SIGNALMENT
It has been suggested that pyometra is a condition of middle aged and older dogs. However, pyometra has been reported in dogs as young as 4 months old and as old as 16 years. A study from Japan of 165 colony-raised beagles revealed a prevalence of 15.2% in nonspayed female dogs over the age of 4. In this study, the average age of onset was about 9 years. A Swedish study reported the prevalence of pyometra at about 25% in intact, publicly owned female dogs under the age of 10 and about 2% in bitches more than 10 years old. In yet another survey, the mean age of dogs presenting with pyometra was 2.4 years. The younger age was attributed to the frequent administration of estrogens for mismating in this population.
Pyometra can occur in any breed of dog. Not all studies have confirmed a breed disposition. Meanwhile, previous pregnancy has been reported to be protective in some dog breeds but not in all.
CLINICAL SIGNS
The clinical signs associated with pyometra typically appear one to three months after the completion of estrus. Most of the clinical signs are not specific for pyometra, including lethargy, depression, pyrexia, anorexia, vomiting, diarrhea, polydipsia, and polyuria. A serosanguineous to mucopurulent vaginal discharge can be seen if the cervix is open. Vaginal discharge may be the only clinical finding in some patients.
In patients with closed-cervix pyometra, vaginal discharge may not be present. Dogs with closed-cervix pyometra are often more seriously ill at the time of diagnosis than those with open-cervix pyometra. A closed cervix inhibits the elimination of the infectious uterine material, delaying the recognition of illness and increasing the likelihood of complications such as septicemia, endotoxemia (most commonly associated with E. coli infection), and septic peritonitis. Bacterial contamination in cases of septic peritonitis may be the result of uterine rupture, translocation of bacteria across the diseased uterine wall, or, less likely, oviduct leakage. More severely afflicted closed-cervix patients may present with signs of shock, dehydration, or collapse.
DIAGNOSTIC TESTING
A history of recent estrus and typical clinical signs, especially vaginal discharge, should raise your suspicion for pyometra. In patients lacking vaginal discharge, the diagnosis can be more challenging. An enlarged uterus may be palpated within the abdomen; however, aggressive attempts at palpation should be avoided to prevent inadvertent uterine rupture. Other potential causes of vaginal discharge or uterine enlargement, including pregnancy, estrus, hydrometra, mucometra, vaginitis, neoplasia, and uterine torsion, need to be considered as differential diagnoses.
Laboratory findings
Laboratory findings in patients with pyometra are not specific for pyometra and frequently reflect the presence of inflammation and secondary metabolic disturbances. The results of a complete blood count will often demonstrate a neutrophilia with a regenerative left shift; however, a normal white blood cell count or even a neutropenia with a degenerative left shift may be identified in animals with endotoxemia. Chemotactic chemicals released from the inflamed uterus attract neutrophils to the uterine lumen where they become sequestered. Eventually, the bone marrow may not be able to keep up with the demand for mature neutrophils, leading to a degenerative left shift. A high white blood cell count may be seen after surgical removal of the uterus, as neutrophils are no longer sequestered. Mild normocytic, normochromic anemia has been documented in dogs, possibly secondary to bone marrow suppression associated with the uterine inflammation and its associated toxemia.
The most commonly encountered biochemical abnormalities reported include elevated alkaline phosphatase and alanine transaminase activities, and blood urea nitrogen (BUN), creatinine, globulin, and total protein concentrations. Bacterial endotoxemia and reduced liver perfusion are thought to contribute to the elevated liver enzyme activities. Dehydration will frequently contribute to elevated BUN and creatinine concentrations, although concurrent kidney insufficiency in an older dog may also be responsible for the azotemia. Kidney damage secondary to immune complex deposition has not been substantiated in recent studies. Hyperglobulinemia and elevated total protein concentrations can occur secondary to chronic inflammation and dehydration. Although less commonly encountered, hypoglycemia can be attributed to septicemia.
Urinalysis findings can be variable. Many patients will have a high urine specific gravity secondary to dehydration. In other patients, the urinalysis will reveal isosthenuria, hyposthenuria, proteinuria, or bacteriuria. The loss of urine-concentrating ability by the kidneys reported in some patients may be secondary to bacterial endotoxin impairment of renal tubule function. Meanwhile, the presence of severe proteinuria at the time of treatment has been associated with the future development of renal failure in some dogs. To retrieve urine for evaluation, a free-catch sample is preferred. Collecting urine by cystocentesis—even if performed with ultrasound guidance—can lead to inadvertent uterine puncture and subsequent leakage of infectious material into the peritoneal cavity.
Radiography
Abdominal radiography can raise suspicion for pyometra. Lateral radiographic projections may reveal craniodorsal displacement of the small bowel and a contorted homogeneous tubular opacity in the caudoventral abdomen. The ventrodorsal radiographic projection may reveal cranial and medial displacement of the small bowel. Both tissue-dense uterine horns can sometimes be visualized.
However, radiography can be insensitive for detecting pyometra since uterine distention typically cannot be detected until the diameter of the uterus is larger than that of the adjacent small bowels. In addition, radiography cannot distinguish pyometra from other causes of uterine distension, such as mucometra or early pregnancy (prior to fetal skeletal mineralization).
Abdominal ultrasonography is the preferred method for evaluating patients for pyometra. The most common ultrasonographic finding is distention of the uterus with an anechoic to hyperechoic fluid . A thickened and cystic endometrium is suggestive of concurrent cystic endometrial hyperplasia. In patients with uterine rupture, free fluid may be identified within the abdominal cavity, and the omentum may be hyperechoic secondary to bacterial peritonitis. Abdominal ultrasonography can also be used to exclude other conditions that can cause uterine enlargement or vaginal discharge, such as early pregnancy.
Cytology
Vaginal cytology in patients with open-cervix pyometra will typically demonstrate excessive numbers of degenerate neutrophils and intracellular and extracellular bacteria. A cytologic finding of inflammation can be seen in patients with vaginitis and, thus, is not diagnostic of pyometra without additional confirmatory testing. The absence of excessive neutrophils and bacteria in the vaginal discharge would warrant reconsideration of the cause of the patient's condition. Meanwhile, vaginal cytology findings in patients with completely closed-cervix pyometra may only reflect the patient's stage of estrous cycle. Expected cytologic findings during diestrus would include a predominance of intermediate and parabasal cells and, early in diestrus, an influx of nondegenerate neutrophils.

 

Surgical and medical treatment of pyometra
Here are your treatment options—including initial therapy. Whether you treat the condition surgically or medically depends on several factors, especially on whether the owner hopes to breed the dog.
Both surgical and medical management options are available to treat patients with pyometra, and both carry associated risks. The decision to pursue medical vs. surgical management should be based on the clinical stability of the bitch as well as on discussions with the patient's owner concerning the associated risks of treatment and the patient's reproductive value and potential. Bitches with closed-cervix pyometra are at higher risk for uterine rupture and systemic illness.
INITIAL TREATMENT
Dogs presenting with clinical signs of illness or shock should be appropriately stabilized before direct treatment of the uterine disease is attempted. The goals of patient stabilization are to restore normal perfusion of the tissues, correct electrolyte and glucose imbalances, and initiate treatment of infection. Clinically ill patients will benefit from intravenous (IV) fluid therapy and the administration of parenteral antibiotics. In patients not responding to IV support and medical treatment, surgical excision of the infected uterus may be required to remove the source of infection and achieve a successful recovery. The mortality rate associated with pyometra is about 5%, and most of these deaths are due to secondary endotoxemia and shock.
Bacterial culture and antibiotic susceptibility testing of the uterine contents and urine are recommended in all patients with pyometra to confirm the effectiveness of empiric antibiotic therapy. Samples for bacterial culture are most commonly taken from the surgically excised uterus. In those patients undergoing medical management, representative bacterial cultures may be retrieved from the cranial vagina by using double-guarded swabs. It should be noted that bacteria grown from cranial vaginal cultures may not be the same as those present in the uterus. The retrieval of samples for bacterial culture and cytologic evaluation through transcervical endoscopy has also been reported.
All patients being treated for pyometra should immediately begin empiric bactericidal antibiotic therapy. Amoxicillin-clavulanate, or a combination of a penicillin and a fluoroquinolone, is a good antibiotic choice based on historical bacterial causes of uterine infection. The suitability of the empiric antibiotic therapy would then be confirmed by the antibiotic susceptibility results reported from the patient's original bacterial cultures. Antibiotic therapy should be continued for seven to 14 days beyond resolution of the patient's pyometra based on physical examination, laboratory, and ultrasonographic findings.
SURGICAL MANAGEMENT
Regardless of cervical patency, ovariohysterectomy is the treatment of choice for dogs with pyometra that are not deemed reproductively important by their owners. The main advantage of ovariohysterectomy over medical management is that it is both curative and preventive for recurrence of pyometra. A discussion of the ovariohysterectomy procedure is outside the scope of this article and can be reviewed in any veterinary surgical textbook.
Ovariohysterectomy carries significant risk, especially in clinically compromised and septic patients. Potential complications such as low blood pressure, aspiration pneumonia, and cardiac arrhythmia should be discussed with the patient's owner before anesthetizing the dog. In addition, the uterine walls are often friable and easily torn during manipulation, leading to spillage of infected contents into the abdomen (Figure 1). A generous abdominal incision allows for easier exposure and exteriorization of the uterus, therefore minimizing the risk of intra-abdominal rupture. In cases of inadvertent intra-abdominal leakage, abdominal culture followed by copious lavage with warm saline solution should be performed.
After surgery, patients with pyometra may develop wound infections, fistulous tracts, or local swelling of the surgical incision site or may hemorrhage. Referral to an institution with personnel capable of providing advanced anesthetic monitoring and postoperative care may be warranted, especially in systemically ill patients that require intensive monitoring.
MEDICAL MANAGEMENT

Both dogs with open-cervix or closed-cervix pyometra can be successfully treated with medical management. Medical management of pyometra is best performed in patients of appropriate breeding age that are reproductively valuable and free of immediate life-threatening illness, including septicemia, endotoxemia, or organ dysfunction. Closed-cervix pyometra carries an increased risk for complications, primarily uterine rupture.
The initial goal of medical management is to reduce the progesterone stimulation of the uterus, which contributes to making the uterus a favorable environment for bacterial infection. This goal can be achieved by administering medications that promote regression of the progesterone-producing corpora lutea or that block progesterone receptors in the uterus.
Prostaglandins
Prostaglandin F2-alpha is the most commonly used medication to medically manage pyometra in dogs. Prostaglandins induce regression of the corpora lutea (luteolysis) through numerous mechanisms, including constriction of blood vessels responsible for oxygen delivery. As the corpora lutea regress, progesterone production drops. The reduction in progesterone concentrations promotes relaxation (opening) of the cervix, allowing the uterine contents to escape. Prostaglandins also directly stimulate myometrium contraction, thereby promoting expulsion of the infected uterine contents. Although not documented, uterine rupture could occur theoretically if intense myometrial contractions were to precede cervical relaxation.
Dogs treated with injectable prostaglandins frequently demonstrate adverse effects such as abdominal discomfort, vomiting, defecation, urination, tachycardia, restlessness, anxiety, fever, hypersalivation, dyspnea, or panting. Adverse effects are dosage-dependent and cholinergic-like and result from the systemic stimulatory effects of prostaglandins on smooth muscle elsewhere in the body. These adverse effects will usually occur within minutes of administration and can persist for up to an hour or more afterward. The prevalence and severity of adverse effects usually decrease with repeated prostaglandin treatments. An earlier study suggested that intravaginal administration of prostaglandin may be associated with a reduction of adverse effects. Walking the patient immediately after prostaglandin administration for 20 to 60 minutes can be beneficial in minimizing the severity of these adverse effects. If the adverse effects are persistent or severe, pretreatment with anticholinergics and antiemetics has been suggested. Rarely, more serious adverse effects, including cardiac arrhythmias, and anaphylactic shock, have been reported.
Both natural and synthetic prostaglandin formulations have been used to successfully treat pyometra. Their dosages and administration frequencies vary according to the selected protocol. It is important you adhere closely to the recommended prostaglandin product dosing regimen as prostaglandins have narrow safety margins and severe adverse effects can be expected when excessive doses are given. Synthetic prostaglandin formulations, such as cloprostenol, appear to induce fewer adverse effects because of increased specificity for the uterine smooth muscle. In a report of 163 dogs with open-cervix pyometra treated medically with prostaglandins alone, 153 dogs responded favorably.
Dopamine agonists

Dopamine agonists have been used in combination with prostaglandins to treat pyometra. Dopamine agonists act by inhibiting prolactin production by the pituitary gland. Prolactin is luteotrophic. Repeated administration of prolactin inhibitors will induce a rapid drop in plasma progesterone concentrations. Thus, a reduction in prolactin concentrations in the blood would be expected to have a synergistic effect with prostaglandins for promoting regression of the corpora lutea. Dopamine agonists cabergoline and bromocriptine have been administered for this purpose. Cabergoline is often preferred over bromocriptine because it usually has fewer adverse effects. In one study, the combination of cloprostenol and cabergoline was successful in treating 21 of 22 patients with open cervix pyometra. In another study involving both open and closed cervical cases, 24 of 29 patients were successfully treated with this combination.13
Progesterone receptor antagonists
Progesterone receptor antagonists, such as aglepristone, have also been evaluated for the treatment of pyometra. These products competitively bind to progesterone receptors in the uterus, preventing endogenous progesterone from exerting its effect. However, because progesterone-receptor antagonists do not directly stimulate the myometrium to contract and expel the uterine contents, their use as a sole therapeutic agent for treating pyometra may be limited. When combined with cloprostenol, aglepristone was found to be more effective for treating pyometra than aglepristone alone was. Adverse effects are uncommon in patients treated with aglepristone. Aglepristone is not available in the United States at this time.
Prognosis
The patient's stage of diestrus may impact the initial success of medical management. The corpus luteum becomes more sensitive to prostaglandins as it ages. During the first five weeks of diestrus, higher doses of prostaglandins or the concurrent administration of dopamine agonists may be required to achieve luteolysis. Bitches treated during the first five weeks of diestrus are more likely to require retreatment than are those that are treated after the fifth week.
Regardless of the protocol selected, patients undergoing medical management for pyometra should be examined frequently on the days of treatment and again one and two weeks after treatment. The patient's vital signs, mental status, and hydration should be evaluated. The character of the vaginal discharge as well as the ultrasonographic status of the distended uterus should be assessed every few days along with progesterone concentrations. A successful treatment would be characterized by the resolution of vaginal discharge, normalization of physical examination findings and laboratory abnormalities, and the complete evacuation and reduction in the diameter of the uterine horns.
Abnormal laboratory findings have been reported to normalize within 14 days of successful medical and surgical management of pyometra. Any significant deterioration in the patient's clinical condition would warrant diagnostic reevaluation of the patient, initiation of the appropriate supportive care, and, in most cases, the recommendation that medical management be abandoned in favor of an ovariohysterectomy.
For most medical protocols, clinical improvement in the patient's signs is apparent within two to four days of initiating treatment. A treatment failure can be identified by the persistence or recurrence of clinical illness, a purulent vaginal discharge, and persistent or progressive uterine distention beyond the period of expected protocol response. Progesterone concentrations > 0.5 ng/ml are an indicator of ineffective luteolysis. Fluid identified within the abdomen would suggest peritonitis. Patients failing to respond to medical treatment may undergo further medical therapy using the same or a different treatment protocol or may receive an ovariohysterectomy.
Medical treatments may be repeated until they prove successful. Typically, no more than two treatment cycles are required to medically resolve pyometra in most patients. In 163 bitches with open-cervix pyometra receiving medical management with prostaglandins, completely recovered from the infection. Of those 153 dogs, 98 recovered with one course of treatment and 55 required two courses. Medical treatment was discontinued in 10 dogs in this series for various reasons. An early study suggested a poor response of closed pyometra to prostaglandin therapy alone. However, a more recent study combining cabergoline and cloprostenol reported that three out of three dogs with closed-cervix pyometra responded favorably to this combination of drugs.
Bitches successfully treated with medical therapy should be bred during the estrous cycle immediately after treatment. Subsequent pregnancy has been suggested to be protective against the recurrence of pyometra. For reproductively valuable bitches, it is also important to obtain a litter whenever possible. The subsequent reproductive success of intact bitches that have recovered from pyometra varies from 50% to 65%. It has been suggested that those dogs that responded most quickly to treatment were more likely to breed successfully in the future. It is not uncommon for patients successfully treated for pyometra to demonstrate estrus much sooner because of a shortened diestrus period. Bitches with shorter interestrus intervals have an increased potential for recurrence of pyometra because of inadequate time for uterine recovery (remodeling and healing of the endometrium). For this reason, estrus suppression could be considered to delay cycling and promote uterine recovery until breeding is planned.
The prevalence of pyometra recurrence in bitches that have been successfully treated remains undetermined. Recurrence rates have been reported to vary from as high as 77% within the first 27 months after treatment to no additional risk above that of dogs that have never acquired pyometra. Because an increased risk for recurrence may be present, once the owner's reproductive goals for the dog have been achieved, the patient should undergo an ovariohysterectomy.
CONCLUSION
Pyometra is a serious and potentially life-threatening disease of the canine uterus. Patients presenting with pyometra should be stabilized, and the decision whether to pursue medical management or surgical management of the uterine disease should discussed with the dog's owner. Medical management of pyometra is best performed in patients of appropriate breeding age that are reproductively valuable and free of life-threatening illnesses, including septicemia, endotoxemia, and organ dysfunction.

 

Wow, what a good post. I recently had a good Jeep bitch who had to have the ovariohysterectomy. Wanted more info on this but after reading this I think I'm good. She had the closed cervix one though and it was overlooked the first time i took her to the vet because she had a hernia. Went home thinking this was why she hadnt been acting like herself. But after another week of her still not feeling well, not eating good, and her middle started to look weird to me. So i knew something more had to be going on. Took her back to the vet to get bloodwork and an xray. He told me he thought this was what it was and she needed to go into surgery immediately. So she was put in for surgery after I left. Thankfully she made it through and is gaining weight. I had never heard of this and even though I won't be able to breed her, future knowledge is a good thing. I will certainly be more careful and attentive in the future.

 

BUMP KELTIC shared something my vet never even heard of helping diagnose and fix her.THANK YOU KELTIC...
Someone might be going through this and can benifit from it also and needs to be bumped every so often.

 

If your vet never heard of Pyometra I would be looking for a new vet.

 

Have you dealt with it before?Yes she old and outdated but tries to take care of us,another vet mentioned cyrvex cancer but not PYOMETRA, as it seems rare and recomended i take her to a female reproduction speacilist. I read this thread and realized the symptoms are the same and i sure apperciated it.

 

Pyometra is far from rare.


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