Anal Stenosis in a Dairy Calf

Background: Congenital abnormalities, present at birth, affect both structure and function, posing significant challenges in livestock anal atresia is a congenital malformation categorized in 4 types and characterized by complete or partial occlusion of the anal opening. Clinical signs usually manifest within the first days of life due to fecal retention. Diagnosis is based on clinical history and physical examination. Treatment involves surgical reconstruction, with outcomes depending on the type of atresia and the moment of intervention. In this report, we describe the therapeutic management of a 7-month-old mixed-breed dairy calf diagnosed with type I anal atresia, specifically anal stenosis.  Case: A 7-month-old mixed-breed female calf (~80 kg) with weight loss and chronic defecation difficulty since birth presented tenesmus, rectal distension, and a narrowed anal orifice measuring 0.5 cm in diameter. Upon presentation, the calf had a body condition score of 4, in a scale from 1 to 9, showing emaciation and notably underdeveloped relative to peers. The animal was diagnosed throughout clinical evaluation with type I congenital anal atresia (anal stenosis). The herd had no prior similar cases. Under field conditions, after sedation and local anesthesia, surgical correction was performed via anoplasty. Postoperative care involved wound cleaning, antibiotics, and anti-inflammatory treatment. Fifteen days postoperatively, the anal orifice had expanded to 1.3 cm in width and 2.5 cm in height, with marked improvement in appetite, defecation and increased fecal output. Delayed diagnosis adversely affected the calf’s physical development; however, surgical intervention via anoplasty successfully restored fecal elimination. Given the potential for a hereditary component, the owner was advised not to include the calf in future breeding programs and to avoid repeating the parental cross that produced this individual. Discussion: The case report demonstrates that even when surgical correction of type I anal atresia is delayed beyond the neonatal stage, favorable outcomes are achievable in animals without systemic compromise or additional malformations. The 7-month-old calf responded well to anoplasty, with restored fecal passage, improved condition, and no complications during follow-up. These results align with literature indicating that timely diagnosis and proper surgical technique are key to prognosis, though early intervention remains preferable. The case also reinforces the hereditary component suspected in some congenital anorectal malformations, making it advisable to exclude affected animals from breeding and avoid repeating the parental cross. Anoplasty remains the definitive treatment, being feasible under field conditions when performed with adequate technique to improve anal lumen size. Postoperative complications, though uncommon, can include fecal incontinence, infection, wound dehiscence, and restenosis, underscoring the need for regular follow-up and owner education. Congenital anal atresia is a rare yet potentially life-threatening condition in calves, necessitating prompt surgical intervention to restore normal defecation and prevent systemic complications. Early diagnosis and timely treatment are essential to avoid growth retardation and enhance long-term quality of life. This case contributes to the growing body of evidence that surgical correction of anal atresia can successfully restore quality of life, even when performed later in life, although initial growth may be markedly impaired Keywords: anus, atresia ani, anal dysgenesis, fecal retention, congenital abnormality, gastrointestinal.