Pyometra in Large Animals
Pyometra is characterized by accumulation of purulent or mucopurulent exudate in the uterus. In cows, it is invariably accompanied by persistence of an active corpus luteum and interruption of the estrous cycle. In affected mares, the cervix is often fibrotic, inelastic, affected with transluminal adhesions, or otherwise impaired. Mares may continue to cycle normally, or the cycle may be interrupted. Discharge from the genital tract may be absent or intermittent and corresponding to periods of estrus. In general, affected animals do not exhibit any systemic signs of illness, but affected mares may be in poor condition. In both cows and mares, pyometra must be distinguished carefully from pregnancy before treatment is undertaken.
The treatment of choice in cows is administration of prostaglandin F2α or its analogues at normal luteolytic doses. Expulsion of exudate and bacteriologic clearance of the uterus follows in ~80% of treated cases. Although first-service conception rate after treatment may be low, most cows may be expected to conceive within three or four inseminations. The treatment may need to be repeated in ~20% of cows. No intrauterine treatment is recommended in conjunction with the prostaglandin.
In the face of cervical changes, drainage of the affected equine uterus may be virtually impossible. Lavage of the uterus using large volumes of fluid is recommended; however, the condition frequently recurs, and permanent cure in these cases requires hysterectomy or wedge resection of the cervix to allow continual uterine drainage, a salvage procedure that allows continued use of the mare but renders her infertile.
Pyometra is seen in small ruminants, swine, and other species; diagnosis is rendered more difficult by animal size and management practices. If pyometra is diagnosed, evacuation of the uterus is recommended.