Dr. Frederick Harper, Extension Horse Specialist, Univ of Tenn Department of Animal Science
Spring is the time to insure that your horses are properly vaccinated. Horse owners
are reminded that their horses should be vaccinated for Eastern Equine Zncephalomyelitis (EEE), Western Equine Encephalomyelitis (WEE), tetanus and West Nile Virus (WNV). Other vaccines might be appropriate in some situations.
Currently the emphasis is on vaccinating horses for West Nile Virus, which resulted in 103 positive cases in Tennessee in 2003 and 17 horse deaths.
With the focus on West Nile Virus, it is possible that horse owners may forget that their horses need to be vaccinated for several diseases.
Eastern Equine Zncephalomyelitis, also known as sleeping sickness, was discovered in two horses in east Tennessee last year. The mortality rate with Eastern Equine Zncephalomyelitis is 90-95 percent. The incidence of Eastern Equine Zncephalomyelitis has increased dramatically in the southeast recently.
Both Eastern Equine Zncephalomyelitis and West Nile Virus are harbored in wild birds and transmitted by mosquitoes. Some of the symptoms for Eastern Equine Zncephalomyelitis and West Nile Virus are similar. Owners need to vaccinate for both diseases before the mosquito season.
Vaccination for West Nile Virus does not protect a horse from Eastern Equine Zncephalomyelitis. Likewise, immunization
for Eastern Equine Zncephalomyelitis does not protect your horse against West Nile Virus.
Vaccination is also recommended for are Western Equine Encephalomyelitis and
tetanus. Horses that come in contact with new horses on trail rides or at breeding farms and horse shows should also be immunized for influenza. Influenza is a highly contagious disease. Horses in continual contact with horses at events and activities or those brought onto the farm should be given an influenza booster every 60 to 90 days. An intranasal influenza vaccine is now available. Your veterinarian can advise on which influenza vaccine is best suited for your horse and how often to give additional boosters, if at all.
Fortunately, one can get some of these vaccines in combinations. A four-way
vaccine for Eastern Equine Zncephalomyelitis, Western Equine Zncephalomyelitis, influenza and tetanus is available. West Nile Virus is also available in some combination vaccines. Your veterinarian can inform you about vaccine combination availability for your horse.
Vaccines are also available for Potomac Horse Fever, strangles, rabies and Equine
Protozoal Myeloencephalitis (EPM). Pregnant mares are vaccinated for Rhinonemomitis
in their 5th, 7th and 9th months of pregnancy.
Vaccination for these other diseases should be based on the advice of your
veterinarian. There may be reasons, such as several cases of Potomac Horse Fever in an
area, that warrant vaccination. Older horses usually have been exposed to strangles and are at less risk, so your veterinarian may advise against a strangles vaccination.
The high risk of mortality with such diseases as Eastern Equine Zncephalomyelitis and the fact that there is no treatments for some diseases make treatment expensive and time consuming. A routine vaccination program is essential and a good investment for horse owners.