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.
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.1
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.2
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.3,4
Regardless of cervical patency, ovariohysterectomy is the treatment of choice for dogs with pyometra that are not deemed reproductively important by their owners.4 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.
Figure 1. An exteriorized uterus during an ovariohysterectomy for pyometra.
After surgery, patients with pyometra may develop wound infections, fistulous tracts, or local swelling of the surgical incision site or may hemorrhage.5 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.