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West Nile virus vaccine.

The Importance of Keeping Your Horses Vaccinated for West Nile

Routine vaccinations are part of being a responsible horse owner. This month we are focusing on West Nile virus. WNV is a mosquito-borne virus that affects humans and other animals, of which horses represent 96.9% of reported non-human cases. West Nile was first introduced to the United States in 1999, WNV is now found in most states in the United States. 

How do Horses Contract West Nile Virus?

Wild birds are the natural hosts for WNV. Humans and horses are considered dead end hosts. The virus is only transmitted through mosquitoes; humans and horses cannot give it to each other. Although there are many symptoms of WNV, many horses that become infected do not show signs of illness. It is possible to develop neurologic disease even when evidence of the virus is not present in the form of symptoms. The virus enters the bloodstream, where it multiplies, through a bite from an infected mosquito. If the virus crosses the blood-brain barrier, it can cause inflammation of the brain and can lead to death. 

Horses contract the West Nile virus when a mosquito that has previously fed on an infected bird also bites them. This virus is a severe threat to horses, as the mortality rate of those infected is as high as thirty-four percent. The disease can cause serious illness by targeting a horse’s brain, spinal cord, and nervous system. Horses Infected with West Nile virus may have one or more of the following symptoms including inflammation of the brain. 

Common Symptoms: Mild to Severe

  • Lack of coordination (The most common symptom)
  • Low or no appetite 
  • Stumbling or falling 
  • Inability to stand 
  • Paralysis of the lower lip 
  • Muscle twitching 
  • Grinding teeth 
  • Inability to swallow 
  • Head pressing 
  • Colicky appearance 
  • Aimless wandering 
  • Hypersensitivity 
  • Excitability 
  • Excessive sweating 
  • Disorientation 
  • Convulsions 
  • Potential for total paralysis 

If the viral infection worsens a horse may unfortunately need to be euthanized. Typically, for the horses that survive, a full recovery is likely. On average, about two out of three horses that become ill will survive. To keep your horse healthy, it is vital that you maintain their vaccinations, ensuring they also receive the booster. If possible, ensure you do not have any breeding grounds for mosquitos in your horse’s vicinity. Be vigilant by making sure you do not have standing water on your property which is a breeding ground for mosquitos. It is also helpful to clean water buckets weekly and regularly clean troughs or stock them with larvae-eating fish. When irrigating pastures keep standing water to a minimum.  

At High Caliber Performance, we care about the health and well-being of your horses. West Nile virus is a serious threat to equine health, and keeping your herd up to date on their vaccinations can help lower the risk. Have questions or concerned about one of your animals? Reach out today: (281) 744-4247

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