18 Oct Equine Flu and Flu Prevention
Flu Shots and Equine Influenza
Equine influenza is a virus which sporadically occurs throughout the USA. In 2018 we saw 2 significant outbreaks of “flu” in our area. Respiratory infections are not limited to fall/winter months, but do seem to be more commonly seen at this time. This may be perhaps due to more indoor housing and/or stress from changing temperatures. Also, fall is a time when many young horses start into training, and attend their first shows, etc.
Horses in the outbreaks we experienced presented as suddenly VERY sick with fevers over 106, severe depression, anorexia, some had a cough, muscle soreness/weakness, and nasal discharge. In horses with a severe respiratory infection it is also very common to get a secondary bacterial infection, such as pneumonia. The incubation period is very short with influenza, seeing clinical signs as quickly as 3-5 days after exposure. Generally horses under age 5, and older horses or horses with other conditions show more severe clinical disease. Some horses rebounded very quickly, others took up to 4-6 weeks before they were able to return to work due to extreme side effects.
Have you gotten your Flu shot yet this year? Has your horse?
Horses at risk generally need to have co-mingling/ contact with other horses. Show grounds, race tracks, etc are areas in which the risk is highest. Young,
potentially stressed horses who have contact with each other (either directly or indirectly) are the perfect contenders for respiratory viruses to spread.
Like in humans, the transmission of influenza is through inhalation of droplets (up to 50 yards) or on materials such as hands, buckets, clothing, etc. Horses continue to shed infective virus for 7-10 days post infection. The virus stays viable for up to 3 days in the environment.
At least 2 weeks prior to travel horses should be vaccinated/ boostered for influenza. The vaccine has been found to not give great immunity for the full 12 months so vaccination every 6 months is indicated in horses who travel or live at barns where other horses are travelling. Influenza is found in many of the combination vaccines (6-way, etc), found in the commonly given “Rhino/flu” vaccine which is an excellent vaccine for respiratory diseases, and also can be given alone in either an injectable or intranasal form. In the face of an outbreak the intranasal vaccine is able to provide good immunity in under 5 days of administration, even in a previously unvaccinated animal.
Please discuss with your vet if an influenza vaccine is appropriate for your horse.