Equis ISSN 2398-2977


Contributor(s): Susan Dawson, Melissa Kennedy




  • Family:Reoviridae.
  • Genus:Rotavirus.


  • L:rota- wheel.

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Clinical Effects



  • Subclinical intestinal infection; rotaviruses are generally host-species specific.
  • Fecal contamination of environment.


  • Feco-oral.

Pathological effects

  • Infected animals develop local and systemic immune responses.
  • Poor hygiene, overcrowding, stress and poor nutrition can lead to decreased immunity and rotaviral diarrhea   Diarrhea: foal - Rotavirus  .
  • Mares' milk and colostrum contain rotavirus antibodies (IgA) which provide protection for several weeks after foaling.
  • Virus infects mature enterocytes   →   malabsorption   →   poorly established colonic microflora of foals   →   unable to convert nutrients to volatile fatty acids   →   diarrhea.
  • Some cases show intestinal ulceration.
  • Clinical signs: depression, mild colic   Abdomen: pain - adult  , anorexia , abnormal gut sounds, watery or pasty diarrhea .
  • Usually in foals 2 days to 4 months old.
  • Mild infections may result in enterocyte damage and ill-thrift.
  • Concurrent salmonella   Intestine: salmonellosis  infection may make disease more severe.

Other Host Effects

  • Many infections are subclinical, especially in adults; rotaviruses are enzootic in equine populations.
  • Many animals show subclinical infection, therefore development of rotaviral diarrhea depends on various predisposing factors, eg climate, stress, age, intestinal flora, viral load and virulence, and hygiene.


Control via animal

Control via chemotherapies

  • Anti-ulcer therapy may be necessary, eg ranitidine   Ranitidine  and sucralfate   Sucralfate  .

Control via environment

  • Management: minimal movement of mares and foals.
  • Disinfection of stables.
  • Good hygiene.
  • Foals must receive adequate colostrum.


  • Rotavirus vaccination of pregnant cows increases specific immunoglobulin in colostrum and milk.
  • Similar strategies may be developed for horses.


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Further Reading


Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Netherwood T, Wood J L, Townsend H G, Mumford J A & Chanter N (1996) Foal diarrhea between 1991 and 1994 in the United Kingdom associated with Clostridium perfringens, rotavirus, Strongyloides westeri and Cryptosporidium spp. Epidem Infect 117 (2), 375-383 PubMed.
  • Dugdale D (1992) Outbreak of rotavirus diarrhea in 2 successive years on a studfarm. Equine Vet Educ (5), 233-236.

Other sources of information

  • Snodgrass D R (1992) Foal rotavirus - can we learn anything from calf scour? Equine Vet Educ (5), 245-247.
  • Proudman C (1992) Rotaviral diarrhea in foals - current concepts. Equine Vet Educ (5), 216-218.