Dynamic chronic rectal obstruction causing a severe colonic dilatation in a cat

Abstract

Case summary: A 5-year-old male neutered domestic shorthair cat was presented to our referral centre with a 13 month history of chronic tenesmus due to malunion of the right caudal iliac body. Constipation and pelvic canal stenosis were initially addressed by the referring veterinarian with a right femoral head and neck excision and a right acetabulectomy without observable clinical improvement. At admission, abdominal radiographs revealed severe colonic distension and a narrowed pelvic canal caused by the right proximal femur. Rectal examination and colonography revealed a dynamic compression of the rectum, which worsened with femoral abduction and improved with femoral adduction. A right hindlimb amputation was performed to relieve the obstruction. The cat defaecated 2 days postoperatively and was discharged uneventfully. Neither faecal tenesmus nor dyschaezia were observed over the following 10 months.

Relevance and novel information: The dynamic nature of the rectal obstruction most likely prevented the development of an irreversible colonic dilatation leading to a megacolon. This is the first report describing a chronic dynamic rectal compression, which was successfully managed with a right hindlimb amputation without the need for subtotal colectomy.

Figure 1

Ventrodorsal pelvic radiographs (initial referring practice radiographs). Malunion of the right caudal iliac body (left arrow) and malunion of the left caudal acetabulum (right arrow). Sacral index of 0.48 (52% of pelvic narrowing, according to Hamilton et al). R = right; L = left

Figure 2

Right lateral caudal abdominal radiograph (initial referring practice radiographs). Colonic diameter 3.7 cm. Ratio of colonic diameter to L5 length is 1.61, compatible with megacolon (a ratio >1.48 is suggestive of megacolon, according to Trevail et al)

Figure 3

Right lateral caudal abdominal radiograph (admission radiographs at our referral hospital; 13 months after initial referring practice radiographs). Colonic diameter 3.0 cm. Ratio of colonic diameter to L5 length is 1.3, compatible with colonic distension

Figure 4

Ventrodorsal pelvic radiograph (admission radiographs at our referral hospital, 13 months after initial referring practice radiographs). Right acetabulectomy and femoral head and neck excision can be observed on the right hemipelvis. Sacral index of 0.38 (62% of pelvic narrowing). R = right; L = left

Figure 5

Right lateral caudal abdominal radiograph after colonography (1 day after admission at our referral centre). Colonic diameter 3.4 cm. Ratio of colonic diameter to L5 length is 1.48, compatible with borderline megacolon

Figure 6

Ventrodorsal pelvic radiograph after colonography (1 day after admission at our referral centre). Rectal stricture of 2 mm can be seen due to abduction of the right femur. Sacral index of 0.07. Narrowing of the pelvic canal of 93%. R = right; L = left

Figure 7

Right lateral caudal abdominal radiograph taken 2 days after right hindlimb amputation. Colonic diameter decreased to 2.7 cm and megacolon was not observed. Ratio of colonic diameter to L5 length was 1.17 (within normal limits)