While hot summer weather is taking its toll on horses and humans, horse owners need to face the threats brought by mosquitoes and the risks of core equine diseases including tetanus, Eastern and Western Equine Encephalomyelitis and West Nile virus.
Diagram of mosquito to bird to horse and human by West Nile virus
Your veterinarian will help you decide what vaccines are essential for your horse, when they should be administered and at what frequency to help provide optimal immunity.
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Vaccines are available for these core equine diseases and horse owners need to make sure they follow veterinarian guidelines related to keeping horses vaccinated on schedule.
Tetanus
All horses are at risk of development of tetanus, an often-fatal disease caused by a potent neurotoxin produced by the anaerobic, spore-forming bacterium, Clostridium tetani.
Clostridium tetani bacteria are present in the intestinal tract and feces of horses, other animals and humans, and are abundant as well as ubiquitous in soil. Spores of Cl. tetani survive in the environment for many years, resulting in an ever-present risk of exposure of horses and people on equine facilities.
Tetanus is not a contagious disease but is the result of Cl. tetani infection of puncture wounds (particularly those involving the foot or muscle), open lacerations, surgical incisions, exposed tissues such as the umbilicus of foals and reproductive tract of the postpartum mare (especially in the event of trauma or retained placenta).
Clinical signs begin with hyper-responsiveness to noise or movement and progress to horse having erect ears; flared nostrils; elevated head; stiff, erect tail; a stiff-legged gait progressing further to muscle spasms; convulsions and death by asphyxia.
Eastern and Western Equine Encephalomyelitis
Transmission of Eastern Equine Encephalomyelitis (EEE) and Western Equine Encephalomyelitis ( WEE ) viruses is by mosquitoes , and infrequently by other bloodsucking insects, to horses from wild birds or rodents, which serve as natural reservoirs for these viruses.
Human beings are also susceptible to these diseases when the virus is transmitted to them by infected mosquitoes; however, horse-to-horse or horse-to-human transmission by mosquitoes is highly unlikely, because the amount of virus in the blood of horses affected by EEE or WEE is small.
Clinical signs can include behavioral changes, loss of appetite and fever. These clinical signs can progress in 12 to 24 hours to dementia with head pressing, teeth grinding, circling and often blindness. The disease is fatal in up to 90 percent of cases. Surviving horses often have residual mental dullness. Treatment is generally supportive.
West Nile Virus
The West Nile virus is transmitted from avian reservoir hosts by mosquitoes (and infrequently by other bloodsucking insects) to horses, humans and a number of other mammals. West Nile virus is transmitted by many different mosquito species, and this varies geographically.
Clinical signs include fever, lethargy, weakness, altered behavior, somnolence, blindness and other neurological signs including muscle tremors, ataxia and seizures. Approximately 1/3 of horses that develop clinical signs of disease may die. Horses that survive often retain mentaldeficits
Your veterinarian and your vaccine program
Your veterinarian will decide what vaccines are essential for your horse, when they should be administered and at what frequency in order to help provide optimal immunity. For foals, the vaccination history of the mare will help determine at what age their initial vaccines can be given.
The foal’s susceptibility to disease and ability to mount an appropriate immune response to vaccination, based on the presence or absence of maternal antibodies derived from colostrum, should be discussed with your veterinarian.
More information on vaccination guidelines for both adult horses and foals can be found on the American Association of Equine Practitioners website: www.aaep.org.
Press release by Zoetis