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What are Vesicular Stomatitis?

Vesicular stomatitis typically starts out as a fever and then symptoms such as loss of appetite due to lesions in the mouth and sloughing of the tongue follow. Your horse may also experience lameness if his coronary band develops coronitis. Diagnostics mainly consist of serologic testing for antibodies which can identify which virus is affecting your horse. There is no exact treatment for this condition, but the disease itself is self-limiting. Most horses recover well with very little supportive care making prognosis of recovery good.

Vesicular stomatitis is a reportable disease in many regions and should be taken very seriously. While many horses have a good prognosis for recovery, this is a serious condition that should be evaluated. If you suspect your horse may have contracted the disease, contact your veterinarian immediately. Once confirmed, state and federal animal health officials should be alerted.

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Symptoms of Vesicular Stomatitis in Horses

  • Fever
  • Ptyalism (hypersalivation)
  • Loss of appetite 
  • Ulcers and erosions of oral mucosa
  • Sloughing of tongue
  • Lesions at the junction of the lips
  • Coronitis with erosions
  • Lameness 
  • Crusting lesions (muzzle, abdomen, sheath, udder)

Incubation time of vesicular stomatitis ranges from 2 to 8 days. Fever is usually the first symptom to develop and then resolve before the other symptoms appear. 

Types

Vesicular stomatitis is related to several different viruses. These viruses are endemic to South and Central America as well as Mexico. Outbreaks have occurred in North America in multiple years throughout history. Transmission occurs when an infected animal comes into direct contact with a non-infected animal. Transmission can also occur when a blood-feeding insect takes a meal from an infected animal and then comes and bites your healthy horse.

Causes of Vesicular Stomatitis in Horses

The viruses responsible for causing vesicular stomatitis belong to the Rhabdoviridae family and the genus Vesiculovirus. In the western hemisphere, the Indiana serotype and New Jersey serotype are the two of interest. These viruses are similar in size and morphology but cause the animal to develop differing antibodies if affected. The specific antibody will be used in diagnosing the disease.

Diagnosis of Vesicular Stomatitis in Horses

In the majority of regions, vesicular stomatitis is a reportable disease making proper diagnosis extremely important. The veterinarian will begin by collecting a history from you such as when your horse’s symptoms began, how long they have been affecting him, if he has traveled anywhere recently, and any other questions that may offer information on your horse’s condition. She will follow with a physical exam and note every symptom your horse is experiencing.

Diagnosing this condition is based on clinical symptoms, antibody detection, viral detection, and detection of viral genetic material. When collecting samples for diagnostics, the veterinarian may want to collect vesicular fluid and epithelial tags or swabs from lesions. The most common serologic tests the veterinarian may choose to utilize are the ELISA test, the complement fixation, and virus neutralization. 

Further diagnostics may be requested by your veterinarian if she wants other information. For example, she may want routine blood work such as a complete blood count and chemistry panel to check organ function and any blood abnormality.

Treatment of Vesicular Stomatitis in Horses

In regards to vesicular stomatitis, there is no specific treatment. If your horse has lesions, cleaning them with a mild antiseptic will avoid a secondary infection from developing. If he is experiencing lameness, stall rest for a short period of time should help. If he is not eating much, softening his food should make it more palatable for him and easier to eat with mouth ulcers present. 

Virus transmitting insects like to live around moving bodies of water so keeping your horse away from streams or rivers can help. When it is insect season for your region, keep them in a sheltered area as much as possible during the insect’s feeding time. You can also apply insecticides to the inner pinna of your horse’s ear to discourage black flies from taking a blood meal from there. Keeping fans in your sheltered area will also discourage blood-sucking insects from landing on your horse and taking a meal since it will be too windy for them to land comfortably. 

Vesicular stomatitis is usually self limiting and will resolve itself somewhere between 10 to 14 days.

Recovery of Vesicular Stomatitis in Horses

The veterinarian will advise on continued supportive care as your horse improves. The most important thing is that he continues to eat so his gastrointestinal system stays in motion, and so colic does not develop. 

Studies have shown some horses who were once exposed to the disease produce antibodies for over 8 years after an outbreak, but sometimes re-infection can occur after a second exposure.