Colic due to dorsally located perirectal abscesses: A retrospective case series of six horses

Perirectal abscesses have only rarely been reported in horses. This case series describes the clinical signs, diagnosis, treatment and outcome of six horses with this condition. The equids affected were geldings or stallions of various breeds and aged from 4 months to 21 years (median age 10 months). Typical clinical signs included colic with tachycardia, tenesmus, dyschezia and abdominal distension. The diagnosis was obtained by transrectal palpation and ultrasonographic examination in five of six horses and by median laparotomy in one horse. All abscesses were located dorsally to the rectum. Rectal impaction and large colon tympany were common secondary findings. Microbiologic examination of abscess content revealed Streptococcus equi subspecies zooepidemicus in all horses. Abscesses were treated by a combination of medical and surgical approaches. One horse had to be euthanised due to complete obstruction of the pelvis by the abscess. In the other horses (5/6), the disorder was associated with an excellent prognosis. In terms of the total population of horses presenting with colic in the investigated period, the prevalence of cases with perirectal abscesses was 0.4%. Although uncommon, described cases indicate that perirectal abscesses should be considered as differential diagnosis for young and mature horses with colic signs.