Equine Influenza Vaccine – New USEF Rules

Equine influenza virus (EIV) is one of the leading respiratory diseases in the United States and, in recent years, the number of infected horses has been on the rise.

Since 2008, Merck Animal Health has collected more than 4700 samples from horses presenting with signs of acute infectious upper respiratory disease and/or acute neurologic disease as part of an ongoing research program. The 2 leading diagnoses, based on samples submitted from horses of all disciplines and ages across the United States, have been equine herpesvirus-4 and EIV.

In an effort to protect horses against these 2 prevalent respiratory diseases, the United States Equestrian Federation (USEF) will implement a rule effective 1 Dec 2015, mandating that all horses be current (within 6 months) on their EIV and equine herpesvirus vaccines prior to entering a USEF show.

Kent Allen, DVM, volunteer chair for the USEF veterinary committee and drug and medications committee, believes the rule change will benefit both horses and show competitors.

“This rule change and uniformity of rules is going to help us not only better protect our horses against infectious upper respiratory diseases, but it also will improve the welfare of these show horses,”
Allen said. “It is important for every owner, as well as the entire USEF organization to ensure that each horse is adequately protected through appropriate vaccination.”

Allen said the new rule will be straight-forward and easy for USEF competitors to implement.

“The bottom line is your horse must be current on the equine influenza and equine herpesvirus vaccines by 1 Dec 2015,” he said. “If you maintain this vaccination schedule and obtain appropriate documentation, you will not only comply with the rule, but you also will ensure your horse is adequately protected against these highly contagious respiratory diseases.”

Even if you do not compete in USEF shows, EIV should still be a top-of-mind disease concern for all horse owners.

“This highly contagious virus can infect an entire barn of horses in less than 48 hours and it can take weeks to months for each infected horse to completely recover,” said D Craig Barnett, DVM, Merck Animal Health director of equine veterinary technical services. “Owners and veterinarians alike need to make sure horses at risk for EIV are adequately protected through appropriate vaccination.”

There are several different EIV vaccines available, including an intranasal option. Allen said he uses this product (FluAvert IN) because of its unique intranasal application.

“The athletes in my care need all of their muscles to compete at the highest level,” Allen said. “Any time I can avoid disrupting the muscles they use to compete, I will. I find the intranasal administration of the vaccine to be a superior delivery method.”

This intranasal product has been proven safe and effective in numerous studies, even in horses with compromised immune systems from traveling and/or training. And, researchers continue to study the product and its efficacy. For instance, a new study conducted at Colorado State University demonstrated how the product stimulates a non-specific, innate immune response at the site of respiratory infections: the upper respiratory tract. This non-specific immune response may help provide some degree of protection against not only EIV, but other respiratory pathogens as well, researchers said.

Influenza is one of the most common and contagious equine respiratory diseases and can lead to significant time away from the saddle. If your horse travels, is in training, shows, races, is young or old, and/or comes in contact with other horses that meet the mentioned criteria, then he is at risk for contracting EIV.

“Owners need to be concerned about infectious upper respiratory diseases, especially the most prevalent like EHV-4 and EIV,” Barnett said. “Although they are not typically fatal, they can require significant recovery time and are certainly uncomfortable for the horse.”