Cause:
These are thought to be congenital abnormalities. There is one case reported from a bison herd that was maintained for nearly 20 years by inbreeding (67).
Clinical signs:
The clinical signs reported include poor growth, rough hair coat, periodic episodes of diarrhea, and chronic bloat (67).
Diagnosis:
The affected bison in the report did not have an anus (67).
Postmortem findings:
The rectum ended blindly, and there was a small fistula between the rectum and the vaginal vault (67).
Treatment:
The only treatment that would have any chance of success would be surgical correction of the condition. In cattle the condition can sometimes be corrected if the blind end of the rectum is very close to where the opening of the anus should be. Surgical correction was not attempted in the case reported.
Control:
A sound breeding program that includes the introduction of out crosses to the herd should prevent the occurrence of most hereditary diseases.