Equine Rotavirus Vaccine

Veterinarians recommend yearly vaccinations for equine rotavirus in mares. Vaccinating mares helps eliminate the risk of rotavirus infection to new foals. Rotavirus outbreaks occur throughout the world, and treatment costs to a farm with large numbers of sick foals can be devastating. The viral effects become maximized in the youngest animals.

  1. Transmission

    • Rotaviruses transmit by the oral-fecal route when foals eat or lick fecally contaminated materials. The virus enters the digestive system and attaches to the intestinal lining, where it infects the cells and decreases their absorptive capability. Thus, food digestion is impaired and watery diarrhea results in further environmental contamination. A very small amount of feces can contain more than 10 million viral particles, enough to infect an entire herd.

    Signs

    • The virus affects foals less than 14 days of age most severely. Foals more than two months old might show soft feces, but no other signs of sickness. Younger foals stop nursing, become depressed and exhibit watery diarrhea. The diarrhea causes dehydration and electrolyte imbalance, which causes death in severe instances. Careful foal monitoring must be implemented with rotavirus diarrhea.

    Treatment/Prevention

    • Foals cannot be vaccinated for rotavirus, because on infected farms they become sick before their immune systems have time to make the antibodies. Once the foals become infected, fluid therapy and nursing are the only treatment options. Sometimes, coating the intestinal tract with medication or replenishing the gut with probiotics relieves symptoms. Vaccinating the mares is the best option.

    Vaccination

    • Vaccines administered to mares at eight, nine and 10 months of gestation decreases rotavirus transmission to foals. The vaccine enhances antibodies against the virus in the mare's milk, and the antibodies will slowly decrease during the first two months of the foal's life. By the time the foal is susceptible to the virus, clinical signs will be minimal. The vaccine affects only rotaviruses in Group A species. Most outbreaks consist of viruses in Group A, but occasionally, other rotaviruses infect foals.

    Management

    • Adding another vaccine increases production costs, but economics prove otherwise. The expense of an outbreak can economically ruin a farm. Veterinary calls, diagnostics, fluid therapy and medications increase the cost of foaling during a rotavirus infection. Farm management techniques using proper sanitation, isolation and vaccination eliminate most outbreaks. Equine rotavirus vaccine, approved in 1996, has proven safe and effective in decreasing infection in foals.