What is Rotavirus?

Rotavirus is one of the most common causes of foal diarrhoea under the age of 6 months (AAEP, 2021). The younger the foal is affected, the more severe the disease is for them and the more infectious they are. The virus damages the intestinal lining and thus impedes digestion and absorption of food, resulting in severe diarrhoea. 

How do foals get rotavirus?

Foals pick up rotavirus from eating contaminated material such as hay or straw or licking contaminated surfaces. The spread is faecal-oral so foals who are infected will shed the virus in their faeces, leaving other foals who are in contact with them, common surfaces, or equipment at risk of picking up infected faecal particles orally. 

Foals are at particular risk if the mare is not vaccinated against rotavirus and if they don’t receive as much colostrum as they should – also known as the failure of passive transfer (AAEP, 2021). 

If a mare and foal live on a stud or premises where foals have previously suffered from rotavirus, the virus may lay dormant in the environment and also be passed onto the foal by personnel who don’t adhere to proper hygiene and biosecurity measures and spread the virus from one foal to another.

Once a foal ingests rotavirus the incubation period is between 12-24 hours. This means it only takes 12-24 hours before the foal starts to show symptoms.

What are the symptoms of rotavirus?

Foals with rotavirus will suffer from diarrhoea, lethargy, decreased nursing appetite and energy, dehydration, and often but not always a fever. The younger the foal, the greater the severity of the disease, generally. Sometimes an individual foal will be affected or there is a  spreading outbreak amongst a group of foals (AAEP, 2021).

What to do if you suspect your foal has rotavirus

If your foal develops diarrhoea, it is recommended to call your vet immediately. This is especially important if they are very young (around 1 week old), as they can be especially vulnerable and become severely ill very quickly without prompt treatment.

Before your vet arrives, separate the foal and mare from other horses and especially any other foals they might be mixing with. You should treat them as if the foal does have an infection like rotavirus before you get confirmation from your vet’s diagnostic tests, as this will prevent further spread to other foals in the interim. 

How is equine rotavirus diagnosed?

Foals can be diagnosed with rotavirus with a PCR test of their faeces or an ELISA blood test. 

Treatment of rotavirus

You should always be guided by your veterinarian who is handling the case as treatment specifics will vary from foal to foal. The main thing to remember is that early detection and thus treatment makes the prognosis much better for a foal with rotavirus. 

Treatment for rotavirus on foals is usually comprised of supportive therapy such as IV fluids, gastrointestinal protectants, anti-inflammatories and probiotics. Foals will tend to lose a lot of fluid via their diarrhoea and reduce their intake of fluids as they drink less, so it is vital that they receive fluid therapy and this in turn supports the gut as well as the rest of their vital organs.

While you’re treating a foal with rotavirus, proper biosecurity measures are key to preventing the spread to other foals. You should handle the infected foal wearing PPE such as disposable gloves, overalls and boot covers that you can discard before handling others. The foal should also have its own stable management utensils such as a water bucket, feed bowl, wheelbarrow, brush, bedding, etc. that don’t get shared with the rest of the yard. Even if you don’t touch the foal, but touch these items, you should always disinfect your hands afterwards before touching any other foal or item that another foal might come into contact with. Having a disinfectant solution to spray on your boots and disinfectant wipes at the entrance to the quarantined area, makes it easy to remember and keep consistent. 

Once the foal’s symptoms have resolved, they can still shed the virus for up to 3 days (AAEP, 2021). Their quarantine must then also continue for another 3 days in order to prevent other foals from becoming infected after they get reintroduced into the herd.  

Can humans catch rotavirus from foals?

Rotavirus in foals is not known to be zoonotic, which means it doesn’t get passed to humans. However, there is always a risk of coinfection with other viruses or bacteria that may be potential zoonotic agents. Therefore, it is always recommended to follow strict hygiene protocols when dealing with a foal with diarrhoea. 

FAQs

How do you treat diarrhoea in a foal?

Foals will always need supportive therapy when being treated for diarrhoea. This usually comprises fluids, gastrointestinal protectants and probiotics. Depending on what is causing the diarrhoea, they may also have other medical treatments recommended to them by their veterinarian, such as anti-inflammatories or antibiotics. Always consult your vet before treating your foal with diarrhoea.

How long does rotavirus last?

This depends on how old the foal is and how quickly they started to receive treatment for the rotavirus. If your foal has diarrhoea, you should call your veterinarian immediately for advice.

How do you prevent rotavirus in foals?

The most effective way to prevent rotavirus in foals is to adhere to sensible biosecurity measures. For example, if a new foal is due to enter an established herd, set up a 2-week quarantine period before exposing them to the rest of the herd, and monitor them for clinical signs.

If there are any rotavirus-positive foals in the yard, these should be kept separate from any others and every precaution to prevent fomite transmission of the disease should be taken. 

In a yard with lots of foals, adequate and regular disinfection of the stables, equipment etc. will also help to prevent rotavirus infection in foals. 

Finally, to set up foals for success in fighting off infections, it should be ensured that foals consume plenty of colostrum at birth. This will mean that they receive enough antibodies from the mare to fight off the disease themselves. 

This article was written by Alice Barker BVSc MRCVS.

References

https://aaep.org/sites/default/files/2021-03/Rotavirus_Guidelines.pdf