Clinical communication — Kliniese mededeling Surgical uterine drainage and lavage as treatment for canine pyometra

INTRODUCTION By definition pyometra is a pus-filled uterus. Pyometra is typically a post-oestral syndrome in adult bitches associated with a variety of clinical and pathological manifestations of genital and multisystemic disease. Pyometra is most commonly associated with polydipsia, polyuria, abdominal distension, vomition, poor appetite, weight loss and anaemia. A purulent vaginal discharge may, however, be the only symptom in some cases of pyometra when the cervix is open. It appears that the degree of patency of the cervix dictates the severity of the clinical signs to a large extent. Canine pyometra is a life-threatening disease. It is postulated that intrauterine bacteria, which ascend from the vagina during pro-oestrus and oestrus, induce the disease during metoestrus by acting on the progesterone-primed endometrium directly via toxin production, or indirectly by the release of inflammatory mediators. There is a clear association between cystic endometrial hyperplasia (CEH) and pyometra. CEH is a progressive degenerative process and is generally accepted to be the initiating lesion and contributes to failure to shed normally transient uterine infections by compromising the uterine environment and/or local defence mechanisms. Parity and age are significant risk factors in the development of pyometra. Escherischia coli, beta-haemolytic streptococci, Pasteurella multocida, coagulasepositive Staphylococcus spp. and Klebsiella spp. are amongst the organisms mostly isolated from pyometra cases, either in pure culture or mixed infections. As pyometra may have fatal complications, clients opting to retain their bitch’s reproductive capacity should be warned of potential risks of medical or surgical treatments. Pyometra cases show marked haematological and biochemical changes. These changes include elevated total white blood cell counts (WCC), marked left shift, toxic degeneration of neutrophils, elevated serum ALP levels and detection of plasma endotoxin in some cases. Clinical improvement of pyometra cases has been associated with reduction in plasma progesterone concentrations, increased vaginal discharges, reduction in diameter of the uterus as determined by ultrasonography and normalisation of haematological and biochemical profiles. Treatment of canine pyometra with prostaglandins (PG) is successful with clinical recovery rates approaching 80 % and post-treatment pregnancy rates attained varying from 40 % to 80 %. Prostaglandin F2α (PGF2α) facilitates smooth muscle contraction in the uterine wall leading to expulsion of uterine contents in cases of pyometra. It is this expulsion of uterine contents that is suspected to be responsible in part for recovery. The duration of prostaglandin administration is thus dictated by the uterine dimension, time it takes for vaginal discharges to subside and ultimately by return of the WCC to normal and the patient to clinical normality. To compare the success rate of treatment protocols for pyometra clinical recovery rates, pregnancy rates, litter size, recurrence rates and duration of treatment should be considered. In some cases, the duration of treatment is of concern. In a retrospective study, some dogs were treated with PG for up to 26 days and in another for over 3 weeks before cure was achieved. There are cases of canine pyometra refractory to PGF2α therapy and cases that recur at subsequent cycles. This accentuates the importance of immediate breeding after treatment. Combination therapy using prostaglandins with either dopamine agonists or progesterone receptor antagonists have been used to successfully treat spontaneously occurring cases of pyometra. In one study using cabergoline and cloprostenol clinical recovery was attained within 14 days in over 90 % of cases, with a pregnancy rate of 64 %. Combination therapy is probably the preferred choice in closed cervix pyometra as aglepristone was reported to open a closed cervix in approximately 48 h following the 1st administration. When combined with cloprostenol the clinical recovery rate was 84 % but the treatment frequently lasted up to 28 days. Intra-uterine antibiotics and antiseptics including povidoneiodine have been used successfully in treating uterine infections in cows. Intra-uterine infusions of saline, EDTATris, chlorhexidine gluconate and antibiotics have similarly been successfully used in mares. The uterine drainage and lavage as illustrated in this study was performed in an attempt to shorten the duration of treatment of pyometra in the bitch as well as achieve both high clinical recovery and pregnancy rates post-treatment.