Pyometra and complete vaginal adhesion in a miniature horse

Abstract

A 4-year-old miniature horse experienced intermittent episodes of pyrexia, lethargy, and purulent vaginal discharge following dsytocia. Vaginal endoscopy and transrectal ultrasonography revealed a blind-ending vaginal cavity and distended uterus. Surgical treatment was declined and the mare was euthanized. Post-mortem examination confirmed the diagnosis of pyometra and vaginal adhesions.

A 4-year-old miniature horse was presented for dystocia 14 mo following fetotomy. Five months following fetotomy the mare had become lethargic, anorexic, and pyrexic. Colitis was suspected and treatment with flunixin meglumine (Banamine; Schering-Plough Animal Health Corporation, Union, New Jersey, USA), trimethoprim-sulfamethoxazole (Novo-Trimel DS; Novopharm, Toronto, Ontario), and bismuth subsalicylate (Kaopectate; Pfizer, New York, New York, USA) was initiated. The mare improved following treatment and diarrhea was never observed. Clinical signs recurred, followed by several bouts of treatment and remission, prior to the presentation at 14 mo post-fetotomy.

Case description

Four months following treatment for suspected colitis, the lethargy and pyrexia returned and at this time purulent vaginal discharge was present. The mare was treated with ceftiofur (Excenel; Pfizer, New York, New York, USA) 2.2 mg/kg BW, IM, UID for 5 d. Over the next several months intermittent bouts of illness occurred accompanied by purulent vaginal discharge. After each episode, the horse’s temperature, demeanor, and appetite returned to normal. Pyometra was suspected, and the mare was treated with cloprostenol (Estrumate; Schering-Plough Animal Health Corporation, Union, New Jersey, USA) 0.79 μg/kg BW, IM every 14 d for 12 wk to lyse the corpus luteum and promote uterine drainage. Uterine lavage was attempted using sterile saline and 1 g gentamicin (Gentamicin Sulfate Solution; Sparhawk Laboratories, Lenexa, Kansas, USA) in 1 L sterile saline was infused. A sterile uterine flush catheter was positioned in what was thought to be the cervix. However, uterine lavage and drainage proved difficult and this prompted vaginal endoscopy which revealed a blind-ending cavity full of purulent material within the vagina.

At this time, the mare was referred to the Ontario Veterinary College (OVC) for a surgical consultation. The mare was now in poor body condition and her haircoat was becoming increasingly dull. Upon presentation to the OVC, the mare weighed 93 kg, had a heart rate of 48 beats/min, respiration rate of 12 breaths/min, temperature of 38.0°C, and pink, moist mucous membranes with a capillary refill time of less than 2 s. Vaginal endoscopy was repeated and the cervix could not be visualized due to scar tissue obstructing the vaginal canal. At this time, the blind-ending cavity identified by the referring veterinarian did not appear to contain purulent material. Transrectal ultrasonography was performed using a 5 mHz linear probe, by attaching a stiff extension formed from a polyvinylchloride (PVC) pipe to the ultrasound probe. The mare’s rectum was gently evacuated of fecal material using lubricated fingertips, the well-lubricated probe and extension were gently inserted into the rectum and manipulated to identify the uterus. The uterus was found to be large and full of purulent material. The ovaries were not identifiable due to the limitations of transrectal ultrasonography in a miniature horse and the large size of the distended uterus. A diagnosis of pyometra and complete vaginal adhesion secondary to dystocia and fetotomy was made.

Due to the chronicity of the pyometra and likelihood of recurrence, a complete ovariohysterectomy was recommended. Surgical correction of the vaginal adhesions and drainage of the uterus was deemed unlikely to resolve the condition. Both surgical options were declined due to financial constraints and the mare was discharged.

Three days later the mare was re-treated with cloprostenol for 1 treatment. Two days after short cycling, purulent vaginal discharge was detected and the mare returned to the referring veterinary clinic for repeat vaginal endoscopy. The cervix could not be identified and the blind-ending vaginal cavity was found to be distended with purulent material. An attempt was made to insert an endotracheal tube and artificial insemination rod through the cavity into the uterus. However, the hole draining the purulent material from the uterus into the vaginal cavity was too small to accommodate either instrument.

At this time the owners elected humane euthanasia. A postmortem examination of the reproductive tract revealed uterine horns that were diffusely enlarged and contained a large amount of purulent material despite draining for approximately 48 h. An incision was made into the body of the uterus and the area was explored for the cervix or another connection between the uterus and vaginal cavity. The uterus was completely separated from the vagina by fibrosis except for a 5-mm drainage tract. Examination of the ovaries revealed a corpus luteum on the left ovary. Bacterial culture and sensitivity performed on a sample of the purulent material revealed presence of Streptococcus zooepidemicus and Pseudomonas spp. Both isolates were susceptible to gentamicin, ceftiofur, enrofloxacin, and rifampicin.

Discussion

A fetotomy is an occasionally necessary but unfavorable option in equine dystocias. The goal of a fetotomy is to quickly decrease the size of the fetus so that safe extraction can occur (1). With prolonged manipulation and traction, cervical and vaginal adhesions are likely and can adversely affect fertility (2). The cause of this mare’s vaginal adhesion and obstruction, which lead to her pyometra, was suspected to be the dystocia and fetotomy 14 mo previously. Dystocia is a common occurrence in miniature horses and their small size complicates fetal manipulation and performance of fetotomy. Equine pyometras most often result from obstruction of the reproductive tract, which prevents uterine drainage resulting in accumulation of exudates and secretions (3).

A retained corpus luteum and anestrus are not consistent findings in the mare with pyometra (4). Bacteria are not always present in equine pyometra; however, S. zooepidemicus, Escherichia coli, Actinomyces spp., Pasteurella spp., Pseudomonas spp., and Propionibacterium spp. are the bacteria most commonly seen (4). Treatment of pyometra in mares with prostaglandin F-2α to promote lysis of the corpus luteum and uterine evacuation is usually the first recommendation, and should be combined with uterine lavage and uterine antibiotic infusion based on culture and sensitivity testing (4). Prostaglandin treatment in this mare was unsuccessful because of the vaginal adhesion obstructing complete drainage of the uterus. Uterine lavage was attempted to remove the purulent debris from the uterus. The benefits of uterine lavage are 4-fold, and include improving efficacy of intrauterine antibiotics by removal of organic debris, reducing bacterial numbers in the uterus, stimulating uterine contractions and clearance, and recruiting neutrophils via transient endometrial irritation (5). By the time the horse was referred to the OVC, the chronicity of the pyometra suggested that uterine lavage and drainage would not prevent recurrence. The prognosis for future breeding following successful treatment of a chronic pyometra is still very poor, as subsequent endometrial atrophy is severe and irreversible (6).

In a study of 17 mares that underwent ovariohysterectomy, pyometra was listed as the indication for this surgery in 13 of the 17 mares (7). In the present study, ovariohysterectomy was considered to have a good prognosis despite the technical difficulties of the procedure and advanced stage of the disease (7). However, for this horse, financial restrictions combined with the level of risk resulted in the owners electing euthanasia. The most important surgical consideration with the procedure is to minimize peritoneal contamination with bacteria and uterine debris (3). For this reason, pre-operative uterine drainage is recommended. For this miniature horse, drainage would have required surgical correction of the vaginal adhesion, since adequate drainage was otherwise not possible. Post-operative complications of equine ovariohysterectomy include incisional infections, intra-abdominal hemorrhage, septic peritonitis, uterine stump infections, abdominal pain, and decreased fecal output or diarrhea (8).

Early diagnosis and management of the pyometra in this mare were complicated by the small size of the patient. Transrectal ultrasonography is possible with a PVC pipe extension on the probe and allows visualization of the reproductive tract as in full-sized horses. Treatment and management options are otherwise similar between miniature and light horses.