Carolina Veterinary Surgical Service
Pyometra is an infection of the endometrium that occurs in dogs and cats during, or shortly after the diestral phase of the estrous cycle. Underlying factors which may predispose the bitch or queen to pyometra include cystic endometrial hyperplasia and exogenous hormone (progesterone, estrogen) administration. Pyometra may be classified according to the status of the cervix as open or closed, the former of which is reflected by the presence of purulent vaginal discharge. Bacterial agents associated with pyometra include E.coli, most commonly, as well as Staphylococcus sp, Streptococcus sp, and others.
Clinical signs that may be associated with pyometra include lethargy, depression, anorexia, fever, vaginal discharge, vomiting. Some cases may present with history of polyuria and polydypsia, which may occur in response to E. coli endotoxins.
Those patients affected with closed pyometra tend to be much more ill at presentation - these cases are less likely to be recognized early by owners as vaginal discharge is not a feature of the disease. Cases which present late in the disease process may be severely dehydrated and moribund. In many cases, abdominal distention is visible. Abdominal palpation may reveal a soft, doughy mass in the mid/caudal abdomen - care must be taken in palpating the abdomen of an animal suspected of having a distended uterus as there is the potential to perforate the viscus.
Most cases of pyometra will exhibit a marked increase in the white blood cell count, although some patients with open pyometra will have leukocyte counts within the normal range. A significant left shift may also be noted, particularly in cases of closed pyometra. Alterations in the biochemical profile may include pre-renal azotemia, hypoglyemia and mild elevation of alkaline phosphatase.
Uterine enlargment is easily identified in most cases of pyometra. Inability to visualize the uterus on survey films does not necessarily rule-out pyometra. Peritoneal sepsis associated with uterine rupture may also decrease the visualization of the abdominal viscera. The main rule-out to be distinguished from pyometra for uterine enlargment is pregnancy, keeping in mind that fetal calcification does not occur until week 6 of gestation. Ultrasonography may be of considerable value where the diagnosis is in question.
The recommended treatment for pyometra is ovariohysterectomy following appropriate patient stabilization to include aggressive IV fluid therapy, initiation of antiobiotic treatment (broad-spectrum), and IV dextrose where necessary. Prognosis with surgical therapy is usually good, although dogs that present with severe septicemia may have a guarded prognosis.
Complications which may occur include sepsis, and its sequelae e.g. DIC, cardiac arrhythmias, organ failure. Close post-operative monitoring and aggressive treatment is essential in complicated cases.
Medical treatment of pyometra has been reported, and is most often used in animals whose breeding value is of primary importance. This mode of treament is less successful than surgical managment, and carries a higher risk of complications. Dogs with closed pyometra are less likely to respond to medical treatment than those with open pyometra, and are more susceptible to developing life-threatening complications. Additionally, recurrence of pyometra with subsequent estrous cycle(s) is a significant possibility in those cases which respond to medical treatment.
Pyometra is a preventable disease - complete ovariohysterectomy (spay) performed prior to onset of the first estrous cycle will eliminate the risk of pyometra. Additional medical benefits to spaying include reduced risk of mammary (if spayed prior to second estrous cycle) and ovarian/uterine cancers. Spaying and neutering non-breeding animals will also help alleviate the problems of overpopulation and animal abandonment / abuse.
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