Fecal retention in a puppy

William J. Downs College of Veterinary Medicine, Cornell University, Ithaca, NY

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Christopher R. Tollefson College of Veterinary Medicine, Cornell University, Ithaca, NY

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 MS, DVM, DACVR

History

A 16-day-old 0.5-kg intact female Boxer dog was presented for a 16-day history of not passing stool since birth and formula coming from the nose during nursing. The dog was urinating normally and had been nursing normally until the day of presentation, when hyporexia was noted. On physical examination, the dog was bright, alert, and responsive and was mildly dehydrated, estimated at 6% to 7%. The dog’s abdomen was tense and moderately distended. No anal orifice was grossly detected but no other developmental abnormalities such as cleft palate or open fontanelles were appreciated. Point-of-care blood work, including a PCV, total solids, and spot blood glucose, was unremarkable. Abdominal radiographs were obtained (Figure 1).

Figure 1
Figure 1

Right lateral (A) and ventrodorsal (B) abdominal radiographic images of a 16-day-old (0.5-kg) intact female Boxer dog with a history of fecal retention since birth.

Citation: Journal of the American Veterinary Medical Association 261, 9; 10.2460/javma.23.05.0233

Diagnostic Imaging Findings and Interpretation

The colon is severely dilated and contains a large volume of structured, soft tissue opaque, fecal material (Figure 2). The colonic diameter measures approximately 97% of the height of the pelvic canal on the lateral projection. The rectum is diffusely gas filled and abruptly ends in a blind sac approximately 0.5 cm from the external anal dimple. Portions of the small intestine are identified by the presence of diffuse, moderate intraluminal gas dilation. Non-aerated small intestine is not visualized due to organ crowding and poor abdominal serosal detail normally present in puppies (lack of fat, brown fat).

Figure 2
Figure 2

Collimated images of Figure 1. Diffusely severely dilated large intestine with abnormally large amount of retained fecal material (arrows), diffusely mildly dilated gas-filled small intestine (arrowheads), and a rectum abruptly terminating in a blind gas-filled sac (asterisk) are seen.

Citation: Journal of the American Veterinary Medical Association 261, 9; 10.2460/javma.23.05.0233

In concert with clinical history, radiographic images demonstrated abnormal fecal retention and small intestinal dilation secondary to the colonic obstruction. Based on the radiographic changes and physical exam findings, atresia ani was diagnosed.

A fluoroscopic positive contrast vaginogram was performed to evaluate for a colovaginal fistula. Iohexol was injected via a red rubber catheter into the vagina (Figure 3). No abnormal diverticula or evidence of fistulas were detected.

Figure 3
Figure 3

Chronologic still images from a positive contrast fluoroscopic fistulogram performed on the dog in Figure 1. Contrast agent (iohexol) is seen entering and pooling in the vagina before exiting through the vulva. No contrast agent is seen in the rectum.

Citation: Journal of the American Veterinary Medical Association 261, 9; 10.2460/javma.23.05.0233

Treatment and Outcome

An anoplasty was performed to repair the atresia ani. A small skin incision was made into the center of the anal sphincter and the underlying tissues were sharply and bluntly dissected until the blind pouch of the rectum was reached. Care was taken to preserve the anal sacs and ducts during dissection. The blind end of the rectum was excised, and a simple interrupted pattern was used to appose the mucosa and submucosa of the rectal opening to the skin of the anus.

Subsequent follow-up revealed intermittent constipation and tenesmus that required multiple enemas. The constipation initially started to develop approximately 2 weeks post-operatively and continued intermittently for 3 additional months. The dog was maintained on lactulose as needed for softer stool. A ballooning and de-obstipation procedure under general anesthesia was performed 1 month post-operatively to correct a perianal stricture. Topical pramoxine and hydrocortisone were prescribed to help prevent future strictures. Most recent recheck examination (2 months post-operatively) revealed normal defecation, healthy rectal tissues, and no other abnormalities.

Comments

Atresia ani is a developmental congenital anomaly caused by failure of the terminal colon and rectum to develop.1 This abnormality is more frequently seen in large animals, especially swine, and is less common in small animals.2 It is rare in the dog, but atresia ani is the most commonly reported anomaly associated with the anus and rectum and can lead to meconium impaction and megacolon.1 Other reported developmental anomalies include atresia recti and coli, fistula, diverticula, and hypospadias.1,3 Females are 1.8 times more likely to be affected.3 Breeds that are overrepresented include poodles and Boston terriers.1,4,5

Atresia ani are classified by type and include congenital anal stenosis (Type I), imperforate anus and blind rectal pouch in close proximity to the overlying skin (Type II), imperforate anus with a more cranial termination of the blind rectal pouch (Type III), and discontinuity of the proximal rectum with normal anal and terminal rectal development (Type IV).1 In this case, type II was present as an anal dimple was identified and the blind rectal pouch was near the perineum.

Physical exam is an essential component of the diagnostic work-up, but imaging is crucial in a supporting role. Abdominal radiographs aid in classifying the type of atresia ani and can confirm fecal retention. They also identify the extent of colonic dilation, which can be a helpful prognostic indicator for risk of developing secondary megacolon.4 Generally, a colonic diameter enlargement greater than 1.5 times the length of L7 is indicative of large bowel dysfunction.5

Sometimes, as in the case described, abdominal radiographs can even identify the blind end of the terminal gastrointestinal tract because of intraluminal gas highlighting the caudal rectum. In addition to partial tail agenesis seen on physical exam, abdominal radiographs can also identify any sacrococcygeal deformities, which have also been reported as occurring in conjunction with atresia ani.3

Contrast studies are a useful tool to diagnose rectovaginal and/or rectovestibular fistulas which are commonly seen concurrently with atresia ani.1 For Types III and IV, more advanced imaging techniques like computed tomography may be necessary to more accurately characterize the extent of atresia ani and for surgical planning, if pursued.

Euthanasia is often elected in cases of atresia ani as treatment with surgical correction may be unrewarding long-term. Prognosis is fair to good, depending on how early surgical intervention is performed. Common post-operative complications include recurrent constipation, perianal stricture, persistent megacolon, and fecal incontinence.

Acknowledgments

None reported.

Disclosures

The authors have nothing to disclose. No AI-assisted technologies were used in the generation of this manuscript.

Funding

The authors have nothing to disclose.

References

  • 1.

    Vianna ML, Tobias KM. Atresia ani in the dog: a retrospective study. J Am Anim Hosp Assoc. 2005;41(5):317-322. doi:10.5326/0410317.

  • 2.

    Kilic N, Sarierler M. Congenital intestinal atresia in calves. Rev Med Vet (Toulouse). 2004;155(7):381-384. Accessed May 7, 2023. https://www.researchgate.net/publication/234032622

    • Search Google Scholar
    • Export Citation
  • 3.

    Ellison GW, Papazoglou LG. Long-term results of surgery for atresia ani with or without anogenital malformations in puppies and a kitten: 12 cases (1983-2010). J Am Vet Med Assoc. 2012;240(2):186-192. doi:10.2460/javma.240.2.186.

    • Search Google Scholar
    • Export Citation
  • 4.

    Rahal SC, Vicente CS, Mortari AC, Mamprim MJ, Caporalli EH. Rectovaginal fistula with anal atresia in 5 dogs. Can Vet J. 2007;48(8):827-830. Accessed May 7, 2023. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1914316/

    • Search Google Scholar
    • Export Citation
  • 5.

    O’Brien TR. Large intestine. In: O’Brien TR, ed. Radiographic Diagnosis of Abdominal Disorders in the Dog and Cat: Radiographic Interpretation, Clinical Signs, Pathophysiology. Covell Park Vet Co; 1981:360.

    • Search Google Scholar
    • Export Citation
  • Figure 1

    Right lateral (A) and ventrodorsal (B) abdominal radiographic images of a 16-day-old (0.5-kg) intact female Boxer dog with a history of fecal retention since birth.

  • Figure 2

    Collimated images of Figure 1. Diffusely severely dilated large intestine with abnormally large amount of retained fecal material (arrows), diffusely mildly dilated gas-filled small intestine (arrowheads), and a rectum abruptly terminating in a blind gas-filled sac (asterisk) are seen.

  • Figure 3

    Chronologic still images from a positive contrast fluoroscopic fistulogram performed on the dog in Figure 1. Contrast agent (iohexol) is seen entering and pooling in the vagina before exiting through the vulva. No contrast agent is seen in the rectum.

  • 1.

    Vianna ML, Tobias KM. Atresia ani in the dog: a retrospective study. J Am Anim Hosp Assoc. 2005;41(5):317-322. doi:10.5326/0410317.

  • 2.

    Kilic N, Sarierler M. Congenital intestinal atresia in calves. Rev Med Vet (Toulouse). 2004;155(7):381-384. Accessed May 7, 2023. https://www.researchgate.net/publication/234032622

    • Search Google Scholar
    • Export Citation
  • 3.

    Ellison GW, Papazoglou LG. Long-term results of surgery for atresia ani with or without anogenital malformations in puppies and a kitten: 12 cases (1983-2010). J Am Vet Med Assoc. 2012;240(2):186-192. doi:10.2460/javma.240.2.186.

    • Search Google Scholar
    • Export Citation
  • 4.

    Rahal SC, Vicente CS, Mortari AC, Mamprim MJ, Caporalli EH. Rectovaginal fistula with anal atresia in 5 dogs. Can Vet J. 2007;48(8):827-830. Accessed May 7, 2023. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1914316/

    • Search Google Scholar
    • Export Citation
  • 5.

    O’Brien TR. Large intestine. In: O’Brien TR, ed. Radiographic Diagnosis of Abdominal Disorders in the Dog and Cat: Radiographic Interpretation, Clinical Signs, Pathophysiology. Covell Park Vet Co; 1981:360.

    • Search Google Scholar
    • Export Citation

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