ISSN 2398-2977      

Equine rotavirus A


Synonym(s): ERVA




  • Family: Reoviridae.
  • Genus: Rotavirus.


  • L: rota - wheel.

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Clinical Effects



  • Subclinical intestinal infection (apparently healthy foals can test positive on qPCR on fecal material); rotaviruses are generally host-species specific where group A rotaviruses have been the causal agent infecting equids, until the recent discovery of a group B rotavirus in foals in 2001.
  • Fecal contamination of environment, and likely transmission via infected fomites.
  • High fecal shedding in diarrheic foals can lead to one case developing into a farm outbreak.


  • Feco-oral.
  • Fomites can be contaminated and serve as a source of virus particles.

Pathological effects

  • Incubation period typically considered to be 12-24 h.
  • Severity of disease affected by age, immune status, viral dose and virulence of the strain. Younger foals being more severely affected .
  • Mares' colostrum, especially in vaccinated mares, contain rotavirus antibodies which provide protection for several weeks after foaling.
  • Virus infects mature enterocytes at the villus tips. This results in villus tip damage causing inflammation, reduced digestive abilities (especially lactase which reside on the villus tip glycocalyx) leading to maldigestion which gives rise to an osmotic diarrhea, as well as malabsorption. This can lead to intestinal dysbiosis and possibly pathogenic bacterial overgrowth.
  • Gastric ulceration has been noted in some sick foals Stomach: gastric ulceration - foal:
    • No evident exists to directly link rotavirus infection with gastric ulceration, the current supposition is that stress, pain and anorexia are likely contributors to gastric ulceration seen in foals at this age with this disease.
    • Some foals have been noted to go and develop duodenal ulcers and subsequent stricture formation but any direct link to rotaviral diarrhea is unknown.
  • Clinical signs:
    • Depression, anorexia, ileus, gastrointestinal tract wall inflammation, abdominal distention and colic in very young foals under a week of age, increased volume watery diarrhea that can on occasion have a slightly reddish-brown color.
    • In foals aged 60-120 days clinical signs can be mild colic, anorexia and watery diarrhea. Foals can be seen to be apparently healthy with normal bloodwork (CBC, serum biochemistry) at 24 h and quite sick at 48 h of age with a degenerative left shift and neutropenia evident on CBC and severe electrolyte derangements (decreased Na, K, Cl, bicarbonate) 24 h later when exhibiting signs of rotaviral diarrhea.
  • Rotavirus A is more commonly seen in neonates under a week of age in foals born to unvaccinated mares.
  • Neonates are more vulnerable to the development of severe clinical signs compared to older foals.
  • In mares vaccinated with the current vaccine (Rotavirus A G[3] genotype) Rotavirus A vaccine milder clinical signs develop in their foals at 60-120 days of age. These infections can be RVA [G3], RVA [G14] or both.

Other Host Effects

  • Many infections are subclinical.
  • Adults do not tend to be affected by rotavirus infection.
  • Rotaviruses are enzootic in equine populations and should also be considered potentially zoonotic.
  • Rotavirus has been identified in feces of normal healthy foals.
  • The development of clinical disease may be associated with factors such as climate, stress, age, intestinal flora, viral load and virulence, and hygiene. However, studies in equines are needed to better understand these factors.


Control via chemotherapies

  • Chemotherapy is limited to supportive care.
  • Gastric ulcer prophylaxis is often indicated, eg microencapsulated omeprazole Omeprazole with or without sucralfate Sucralfate. Ranitidine Ranitidine and sucralfate can also be used in combination as gastric ulcer prophylaxis. Administration of sucralfate is typically recommended at a time when other medications are not also administered.

Control via environment

  • Management: minimal movement and handling of mares and foals, especially during an outbreak.
  • Sanitization of stables after removal of organic material and the use of a disinfectant active against rotavirus under barn conditions.
  • Discontinuation of use of a leaf blower to 'sweep' barns.
  • Attention to hygiene among staff handling foals.
  • Foals must receive adequate colostrum within recommended period after birth.


  • Rotavirus vaccination with the existing conditionally licensed vaccine (RVA[G3] strain) is indicated during every pregnancy Rotavirus A vaccine.
  • A course of 3 doses at 8th, 9th and 10th months of gestation as per manufacturer's recommendations.

Other countermeasures


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Further Reading


Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Uprety T, Wang D & Li F (2021) Recent advances in rotavirus reverse genetics and its utilization in basic research and vaccine development. Arch Virol 166 (9), 2369-2386 PubMed.
  • Carossino M, Barrandeguy M E, Erol E et al (2019) Development and evaluation of a one-step multiplex real-time TaqMan® RT-qPCR assay for the detection and genotyping of equine G3 and G14 rotaviruses in fecal samples. Virol J 16 (1), 49 PubMed.
  • Maguire J E, Glasgow K, Glass K et al (2019) Rotavirus Epidemiology and Monovalent Rotavirus Vaccine Effectiveness in Australia: 2010-2017. Pediatrics 144 (4), e20191024 PubMed.
  • Tamim S, Matthijnssens J, Heylen E et al (2019) Evidence of zoonotic transmission of VP6 and NSP4 genes into human species A rotaviruses isolated in Pakistan in 2010. Arch Virol 164 (7), 1781-1791 PubMed.
  • Carossino M, Barrandeguy M E, Li Y et al (2018) Detection, molecular characterization and phylogenetic analysis of G3P[12] and G14P[12] equine rotavirus strains co-circulating in central Kentucky. Virus Res 255, 39-54 PubMed.
  • Miño S, Adúriz M, Barrandeguy M et al (2017) Molecular Characterization of Equine Rotavirus Group A Detected in Argentinean Foals During 2009-2014. J Equine Vet Sci 59, 64-70.
  • Nemoto M, Ryan E, Lyons P et al (2017) Molecular characterisation of equine group A rotaviruses in Ireland (2011-2015). Vet J 226, 12-14 PubMed.
  • Luchs A & Timenetsky Mdo C (2016) Group A rotavirus gastroenteritis: post-vaccine era, genotypes and zoonotic transmission. Einstein (Sao Paulo) 14 (2), 278-287 PubMed.
  • 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

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

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