Anal Atresia in a Foal

Clinical Case A newborn male Welsh pony foal, born without an anal opening, was admitted for treatment (Figures 1 and 2). On presentation, the foal displayed signs of mild abdominal discomfort indicated by intermittent uneasiness, looking at the abdomen, and stretching into a “sawhorse” stance. The foal was observed to urinate normally. Pulse, mucous membrane color, and capillary refill time were within normal limits. The physical examination revealed no other abnormalities. Before surgery, a simple incision was made through the skin in the anal region using local anesthesia (Figure 3). However, the rectum was not identified by this procedure. In preparation for surgery, penicillin (16 mg/kg q12h IV), gentamicin (3 mg/kg/day IV), and flunixin meglumine (0.6 mg/kg/day IV) were administered. The foal was premedicated with xylazine (1.1 mg/ kg IV) and diazepam (0.01 mg/kg IV), and anesthesia was induced with ketamine hydrochloride (2.2 mg/kg IV) and maintained with isoflurane in oxygen using a semiclosed circuit system. The foal was placed in right lateral recumbency, with its tail pulled dorsally, allowing easy access to the anal region. An 8Fr urinary catheter was placed in the urethra to facilitate intraoperative identification of that structure. To provide sufficient exposure for dissection of the rectum, a midline skin incision was made, extending from 2 cm dorsal to 2 cm ventral to the anal region. Using blunt dissection, the rectal pouch was identified approximately 3 cm cranial to the skin surface. After further blunt dissection of the perirectal tissue, EQUINE