In this episode of the Disease Du Jour podcast, Sally DeNotta, DVM, PhD, DACVIM, joined us to talk about equine infectious disease patterns and emerging threats. She also offered advice on how veterinarians can help protect their patients, especially in the face of natural disasters and climate change.
Equine Vaccination Recommendations
DeNotta said veterinarians and horse owners should focus on the core vaccines designated by the American Association of Equine Practitioners, including Eastern and Western encephalitis, tetanus, West Nile virus, and rabies.
“Rabies tends to be the one that is perceived to be perhaps the lowest risk by many horse owners because it’s quite rare,” said DeNotta. “Although the incidence is low, the risk is very real.” She shared a story about a well-kept, recently imported horse in Central Florida that died from rabiIn this episode, Dr. Sally DeNotta discusses equine infectious disease patterns and emerging threats.es and exposed 20 people to the disease, simply because nobody realized the horse hadn’t been vaccinated.
“I try to get the message out to owners, stakeholders, and veterinarians alike that not only should we not be skipping or prolonging the interval on the rabies vaccine, but we should be really vigilant about making sure that if someone says this horse is up to date, that we’re actually checking and making sure that is correct,” she said.
DeNotta also reminded veterinarians to ensure horses have the correct vaccines when they are traveling to new regions of the country or arriving from Europe. Many horses come to Florida for the winter show circuit from other parts of the country or from overseas, and these horses might not be adequately vaccinated against arboviruses.
“There is a misconception amongst owners, trainers, facility owners, and sometimes veterinarians that we are importing horses that have been vaccinated for U.S. diseases,” DeNotta said. “They think it’s a part of their requirement to leave their home country, which it absolutely is not.” She recalled one horse that had been recently imported from Europe and was showing in Florida that died after contracting EEE because it hadn’t received the vaccine.
Emerging Equine Infectious Disease Threats
DeNotta said veterinarians need to be on the lookout for New World screwworm (NWS), a parasitic worm that eats living flesh and can kill the host animal. This disease was endemic in the U.S. decades ago and was successfully eradicated. However, there has been recent NWS activity in Central America, Costa Rica, and Panama. Because the U.S. shares a border with Mexico, there are concerns about potential encroachment.
“These larvae are susceptible to many anthelmintics, including ivermectin, so there’s no resistance patterns that we worry about,” DeNotta said. “They’re not superbugs; they just shouldn’t be here.” All horses entering the U.S. from Mexico or another endemic country must now be quarantined for an additional seven days, during which time they’re sedated and meticulously examined for any wounds or signs of larva.
Impact of Climate Change on Equine Infectious Disease Patterns
With climate change, “the diseases are coming to an area near you,” DeNotta said. “You don’t have to go anywhere!”
Following severe weather events such as hurricanes, standing water and humid conditions create the perfect breeding ground for mosquitoes, resulting in an uptick in EEE and WNV cases. Severe flooding in the Midwest and Northeast is also causing an uptick in mosquito-borne diseases in areas of the country that previously didn’t see many cases. DeNotta said EEE used to be more of a southeastern disease but now has a strong epicenter in the Great Lakes region. Furthermore, the geographic distribution of ticks infected with Anaplasma and Borrelia is expanding out of the Northeast and moving south.
“As a veterinarian, I would say just be aware that diseases that maybe 10 years ago weren’t really on your radar, you’ve got to keep an eye out,” DeNotta said.
Wildfires are another concern for infectious disease transmission. During an evacuation, horses might move to regions with different endemic diseases. At evacuation centers, many horses are commingling and sharing water sources, which is a huge risk factor for spreading strangles or influenza.
Final Thoughts
In closing, DeNotta advised veterinarians to pay attention to the AAEP’s infectious disease updates and resources, including its webinars featuring experts from around the country. She also recommended subscribing to alerts from the Equine Disease Communication Center and informing clients when there’s a disease outbreak in your region. (To be alerted when an equine infectious disease is reported in your state or surrounding area, sign up here for text alerts for the EDCC Health Watch program, hosted by the Equine Network.)
About Dr. Sally DeNotta
Sally DeNotta, DVM, PhD, DACVIM, is a member of the clinical faculty at the University of Florida College of Veterinary Medicine. She currently serves as the chair of the AAEP Infectious Disease Committee. Originally from the rural Oregon coast, she spent time in private practice in Oregon and Colorado before completing an internal medicine residency and PhD at Cornell University. She joined the UF faculty in 2018, where her clinical interests include equine infectious disease and clinical neurology. When not in the hospital, she is the UF equine veterinary extension specialist, serving as the liaison between the College of Veterinary Medicine and the Florida horse industry.
Related Reading
- A Refresher on Protecting Horses Against Arboviruses
- The Future of Equine Infectious Diseases in a Changing Climate
- Researchers Identify Potential New Transmission Method for West Nile Virus
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