Abstract

Ovariohysterectomy following chronic pyometra in an American Miniature Horse mare

Kaitlyn Steele,^a Korrine Tate,^a Michelle Tucker,^a Justin Hayna^a

^a Purdue University College of Veterinary Medicine, Purdue University, West Lafayette, IN

A 6-year old American Miniature Horse mare was referred for management of chronic pyometra of approximately 4 months duration. History included abortion at 8-9 months gestation, 8 months prior to presentation. Clinical signs consisted of intermittent discomfort and dysuria. Three months prior to presentation, manual debridement of cervical adhesions was performed by the referring veterinarian, temporarily alleviating the clinical signs. On presentation, physical exam parameters were unremarkable, while reproductive exam revealed a grossly inflamed, fibrotic and sealed transverse fold; attempts to bypass the transverse fold and enter the vagina were unsuccessful. Transabdominal ultrasonography showed a large, fluid-filled viscus in the caudal abdomen. The cervix could not be identified. Complete blood count and serum biochemistry profiles were consistent with an inflammatory process. Transvaginal ultrasonography demonstrated a transverse fold thickness greater than 1 cm, thus making it unsuitable for laser ablation. Abdominal computed tomography was performed, which confirmed the diagnosis of a severe pyometra extending cranially to the 11th intercostal space. Due to pain refractory to medical management, an ovariohysterectomy was performed. After partial exteriorization and abdominal packing, the uterus was decompressed through a stab incision using suction. Approximately 8 liters of purulent material were drained. The cervix could not be identified; therefore, intra-operative transvaginal palpation was used to establish the caudal boundary for resection. Sharp resection was performed, and the cranial vagina was closed using 2-layer closure. The uterus and both ovaries were submitted for gross and histopathologic analysis. The uterus demonstrated severe endometritis with marked fibrosis. Both ovaries contained hemorrhagic luteal structures. Culture and susceptibility testing of uterine contents revealed a mixed bacterial growth, with a predominant population of a multidrug-resistant methicillin-resistant Streptococcus pseudintermedius. The mare recovered and was discharged on flunixin meglumine and chloramphenicol. Three weeks following surgery, the client reported the mare was doing well.

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