Rectal Prolapse in Sheep

Genetic or Environmental?

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History

  • One or more layers of the rectum protrude through the anus
  • Commonly known as Rectal Prolapse
  • Cited in Journals as early as 1905

Diagnosis

  • An elongated, cylindrical mass fully or partially protruding from the anal orifice.
  • Early on, there is a short, non-ulcerated and inflamed segment.
  • Later, the protruding surface darkens and may become necrotic.
  • Animals may have trouble defecating while the tissue is protruding.

Genetic Transmission

  • Most common in feedlot (meat breed) lambs on high concentrate diets
  • More common in ewe lambs with more internal (pelvic) fat
  • Early studies showed correlation between tail length and susceptibility to prolapse
  • However, not all lambs with short, medium or long length tails prolapsed, leading researchers to return to genetic causation
  • A study done by Texas Tech at the University Sheep Center showed high genetic correlation:
  • 62.5% of prolapsed lambs (of all tail length) were sired by a single ram.
  • In the trial, the group with medium length tails prolapsed most often

Production Problems

  • Lambs that prolapse are costly to treat
  • Ewes that prolapse rectally as lambs are more likely to prolapse again as mature animals and produce lambs that prolapse themselves.
  • Lambs can die if left untreated.

Eradication Methods

  • Do not breed sheep that have prolapsed.
  • Cull animals that do prolapse.
  • Keep sheep out of dusty environments
  • Feed adequate roughage to feedlot lambs
  • Treat cases of cough immediately

Opinion

More research should be done to determine the genetic cause of rectal prolapse in sheep. Genetic testing similar to tests for scrapie susceptibility and spider lambs syndrome would help sheep producers focus on breeding genetic lines of sheep resistant to prolapse.