Equine flu is an infectious disease affecting the upper respiratory tract of horses. It is endemic in the UK with frequent outbreaks recorded over the last few years.1
A horse with flu needs complete rest and isolation, often putting them out of action for weeks. In addition to this, outbreaks can affect competitions at all levels, potentially resulting in the cancellation of events in order to control the spread of disease.
Clinical signs usually appear within 1–5 days of exposure to the flu virus and can last for 3–6 weeks. They can include a high temperature, cough, nasal discharge, enlarged glands under the lower jaw, conjunctivitis, depression, loss of appetite and filling of the lower limbs.
If your horse shows any of these clinical signs consult your vet immediately, even if your horse has been vaccinated. This will allow appropriate tests to be carried out to determine the cause, and ensure that a suitable treatment plan is put in place. Remember to keep the horse isolated from others during this time as flu is highly infectious.
The equine flu virus evolves and changes constantly and it is important that its development is monitored in order to ensure vaccines protect against the circulating strains. Recent outbreaks in the UK are known to be of a strain called Florida Clade 2 (a sublineage of H3N8).1 Current guidelines from the World Organisation for Animal Health (OIE) recommend that vaccines should contain both Clade 1 and Clade 2 strains of the Florida sublineage.2
Your vet will be able to provide guidance on vaccines and the correct vaccination schedule for your horse.
Diagnosis And Surveillance Of Equine Flu
The Horserace Betting Levy Board (HBLB) Equine Influenza Surveillance Programme at the Animal Health Trust (AHT) provides a laboratory testing service to all vets allowing them to submit swabs taken from horses with suspected flu and confirm not only if flu is present, but also which strain is responsible.
1Equiflunet. Available at: equiflunet.org.uk (Accessed January 2016).
2OIE Expert Surveillance Panel on Equine Influenza Vaccine Composition – conclusions and recommendations (March 2015). Available at: http://www.oie.int/our-scientific-expertise/specific-information-and-recommendations/equine-influenza/
(Accessed January 2016).