Unvaccinated Horses and Eastern Equine Encephalitis (EEE): An Emerging Concern in Ontario

In recent times, Ontario has witnessed a worrying outbreak of Eastern Equine Encephalitis (EEE) affecting its equine populations. The dire consequences of this mosquito-borne disease, especially among unvaccinated horses, prompt a significant call to action for horse owners and veterinarians alike.

Recent Cases Highlight the Growing Threat

Several heart-wrenching cases of EEE have surfaced in Ontario:

  • In the Regional Municipality of Niagara, a 4-year-old gelding developed neurological symptoms on September 6 which led to its eventual euthanasia.
  • In Parry Sound, a 3-year-old Miniature Horse tested positive for the disease and met a similar fate.
  • The City of Ottawa saw the demise of a 15-year-old Thoroughbred gelding, while in the United Counties of Leeds and Grenville, both an 18-year-old Quarter Horse mare and a 4-year-old donkey succumbed to the disease.
  • A particularly tragic case involved a yearling Quarter Horse filly and a suckling foal filly, both testing positive and eventually being euthanized in Leeds and Grenville.

These incidents underscore EEE's lethality and the critical need for comprehensive prevention measures.

Understanding EEE: Causes and Transmission

Eastern Equine Encephalitis is caused by the Eastern Equine Encephalitis Virus (EEEV). This virus is primarily maintained in bird populations and spread by mosquitoes. What's particularly challenging is that while infected horses carry the virus, they don’t reach the virus level required to be contagious to other horses or humans. Thus, the lifecycle of transmission predominantly relies on mosquitoes acting as carriers from wild birds to other hosts, including humans and horses.

Clinical Signs: Recognizing EEE in Horses

EEE is characterized by acute and progressively worsening symptoms. Early signs can include lethargy and incoordination, advancing to more severe neurological problems such as ataxia (loss of control of body movements), recumbency (inability to rise), seizures, and ultimately, death. Given the high mortality rate, it's critical to spot these symptoms early.

Prevention Strategies: A Multifaceted Approach

Due to the high fatality rate associated with EEE, prevention is crucial. Experts recommend a combination of strategies:

Vaccination

Regular vaccination is imperative in protecting horses against EEE. Veterinarians advise annual vaccinations, while equine health organizations may recommend more frequent shots in high-risk areas.

Mosquito Control

Effective mosquito control can significantly reduce the risk of EEE. Here are some practical measures:

  • Use EPA-labeled insect repellents containing DEET, picaridin, or oil of lemon eucalyptus.
  • Ensure homes and stables are mosquito-proof by installing or fixing window and door screens.
  • Eliminate standing water to prevent mosquito breeding grounds.
  • Stock water tanks with mosquito-eating fish or use solutions like Bacillus thuringiensis israelensis "mosquito dunks" which target mosquito larvae.

Stabling Practices

During prime mosquito activity periods, which are typically dusk and dawn, keeping horses stabled indoors can greatly reduce mosquito exposure. This practice is a simple yet effective layer of protection.

Water Management

Regular drainage and cleaning of water troughs and buckets are essential to prevent mosquito breeding. Aim to empty, scrub, and refill these water containers weekly.

A Call for Awareness and Proactive Measures

The recent EEE cases in Ontario emphasize the proactive role horse owners must take. Organizations like the Equine Disease Communication Center (EDCC) play an instrumental role by providing verified and timely information to the equine community. Horse owners must adhere to vaccination protocols, implement stringent mosquito control measures, and stay informed about the best practices in equine health.

In conclusion, the resurgence of EEE serves as a critical reminder of the steps needed to safeguard equine health. By understanding the disease, recognizing its transmission pathways, and adopting effective prevention techniques, horse owners can significantly mitigate the risks and ensure the well-being of their horses.

For further details, visit the original sources from [The Horse](https://www.thehorse.com) and other equine health networks.