Laboratory tests were requested, including a complete blood count and biochemical panel, as well as imaging studies such as abdominal ultrasonography and contrast radiography.

Therapeutic treatment was initiated with meloxicam (0.1 mg/kg every 24 hours for four days), a nonsteroidal anti-inflammatory drug aimed at reducing inflammation, pain, and fever. Cephalexin (30 mg/kg every 12 hours for 10 days) was also prescribed as an antibiotic to prevent bacterial infectious complications. For pain and fever control, dipyrone drops (2 drops every 12 hours for three days) were indicated. Additionally, lactulose (1 mL every 12 hours for three days) was introduced as a laxative to facilitate intestinal evacuation and prevent constipation. Finally, a topical ointment (nystatin, neomycin sulfate, triamcinolone, and triamcinolone acetonide) was recommended for treatment of the perianal fistulas, applied twice daily for seven days after prior cleaning with water and neutral soap.

The complete blood count revealed microcytic normochromic anemia and thrombocytopenia, while the leukogram and biochemical panel were within normal limits. Abdominal ultrasonography showed intestinal inflammatory process and fecal retention, with no other relevant findings.

In the contrast radiographic examination, the barium enema technique was used to evaluate the colon and rectum. This involved prior patient preparation with 24-hour fasting and an enema immediately before the examination for intestinal emptying. Plain abdominal radiographs were obtained in laterolateral (left lateral recumbency) and ventrodorsal projections, revealing intestinal loops moderately filled with heterogeneous and gaseous (fecal) content, indicating fecal retention (Figure 2).

Figure 2 Source: Veterinary Clinic PUC-Campinas (2025). Note: A: Left laterolateral projection (LL); B: Ventrodorsal projection (VD).

Subsequently, barium at room temperature was administered via a size 6 rectal catheter in a volume of 11.2 mL (7 mL/kg) (Thrall, 2014). The procedure was performed under general anesthesia, which is required in most cases. The anesthetic protocol included methadone (0.2 mg/kg) combined with dexmedetomidine (1 mcg/kg) as pre-anesthetic medication, allowing venous catheterization after 10 minutes. This was followed by intravenous administration of ketamine (1 mg/kg) and propofol titrated to effect (2 mg/kg/min) until satisfactory immobilization for the procedure was achieved, reaching a total dose of 6 mg/kg.

Abdominal radiographs were then obtained sequentially: immediately after contrast administration (Figure 3), after 15 minutes (Figure 4), after 30 minutes (Figure 5), and finally after 1 hour and 20 minutes (Figure 6). A moderate amount of radiopaque contrast was observed filling the transverse and descending colon and rectum, with no signs of leakage, progressing through the rectal route and through two perianal fistulas. This finding demonstrated stenosis of the distal rectum, consistent with type I anal atresia.

Figure 3 Source: Veterinary Clinic PUC-Campinas (2025). Note: A: Left laterolateral projection (LL); B: Ventrodorsal projection (VD).

Figure 4 Source: Veterinary Clinic PUC-Campinas (2025). Note: A: Left laterolateral projection (LL); B: Ventrodorsal projection (VD).

Figure 5 Source: Veterinary Clinic PUC-Campinas (2025). Note: A: Left laterolateral projection (LL); B: Ventrodorsal projection (VD).

Figure 6 Source: Veterinary Clinic PUC-Campinas (2025). Note: A: Left laterolateral projection (LL); B: Ventrodorsal projection (VD).

After confirmation of the diagnosis, the patient was referred for corrective surgery. Pre-anesthetic medication consisted of methadone (0.3 mg/kg) administered intramuscularly, followed by venipuncture and administration of dexmedetomidine (2 mcg/kg) associated with ketamine (1 mg/kg). Induction was performed with propofol (2 mcg/kg/min) until an adequate surgical plane was achieved. Maintenance was carried out with isoflurane in a non-rebreathing circular system, combined with continuous infusions of remifentanil (12 mcg/kg/h), ketamine (0.6 mg/kg/h), and dexmedetomidine (0.5 mg/kg/h). A lumbosacral epidural block was also performed using lidocaine (0.22 mL/kg) and morphine (0.1 mg/kg). Throughout the procedure, the patient received lactated Ringer’s solution at a maintenance rate.

For correction of anal atresia, a number 4 urethral catheter was used to identify the anal orifice, followed by a 0.5 cm circumferential incision around the anal fold. After tissue excision, rectal mucosa was anastomosed to the skin using a simple interrupted suture pattern with 3-0 nylon (Figure 7). The perianal fistulas healed by second intention.

Figure 7 Source: Veterinary Clinic PUC-Campinas (2025).

In the immediate postoperative period, the patient received dipyrone (25 mg/kg) and dexamethasone (0.08 mg/kg) subcutaneously, as well as intravenous cephalothin (30 mg/kg). The following medications were prescribed: meloxicam (0.1 mg/kg every 24 hours for four days), cephalexin (30 mg/kg every 12 hours for 10 days), dipyrone drops (2 drops every 12 hours for three days), tramadol hydrochloride 100 mg/mL (1 drop every 8 hours for three days), and lactulose (1 mL every 12 hours for three days). The owner was instructed to perform local cleaning with water and neutral soap and apply cold compresses twice daily for 7 days. Additionally, continued observation was recommended, with veterinary care advised if necessary.

Ten days after the surgical procedure, the wound showed good healing, complete closure of the fistulas, and the dermorrhaphy sutures were removed, indicating positive postoperative progression.

Furthermore, one of the patient’s contacts presented clinical signs of canine distemper during the same period. After confirmation by ELISA testing, all puppies were placed under quarantine. For the present patient, a follow-up complete blood count was recommended, revealing structures suggestive of Lentz bodies (viral inclusions characteristic of canine distemper) in erythrocytes and neutrophils. Symptomatic treatment for distemper was initiated, and ELISA and PCR tests were requested; however, the patient showed acute worsening of the viral condition and died 10 days after suture removal. Due to the condition of anal atresia, fistulas, and previously described complications, the patient had not received primary vaccination and therefore lacked immunity against viral diseases such as distemper.