Knowledge is the key to disease prevention
Infectious diseases are those diseases that horses can get
from each other, or via a vector, such as a mosquito, which
may transmit the disease from horse to horse. Horse owners
can vaccinate their horses against many of these diseases,
or their veterinarian may administer the vaccinations.
Some vaccines are considered "core" vaccines that cover
diseases that all horses need to be immunized against. Some
horses may need to be immunized only when there is significant
risk that they will be exposed to the disease in their natural
environment, or if they may be exposed when traveling, showing,
or competing. In addition, horses must be vaccinated at different
life stages. Most vaccines need to be given annually. Find
a good Vaccine
Schedule to check when your horse needs these immunizations.
Tetanus is caused by a bacterial toxin normally found in the
soil and in the feces of horses. The bacteria that produce
the tetanus toxin need a decreased oxygen supply to multiply,
so any area where there is a deep puncture wound or where
a wound has healed over (such as the navel stump of a newborn
foal) is an area where tetanus can thrive. Symptoms of tetanus
include an elevated third eyelid and stiff neck, progressing
to overall muscle stiffness causing a 'sawhorse' stance. Tetanus
is often fatal, but a yearly vaccine can prevent it, and the
vaccine is a good idea because small cuts can go unnoticed
and become infected.
Equine Encephalomyelitis (sleeping sickness)
This is a disease that affects the nervous system, and can
be caused by equine encephalomyelitis viruses (Eastern, Western,
and Venezuelan), which are carried by mosquitoes. Signs include
depression and a high fever, followed by a period when the
horse appears blind, nervous and uncoordinated, which progresses
to muscle tremors, yawning, and eventually, complete paralysis.
Proper vaccination and good mosquito control are important
to help prevent this disease.
This viral disease is spread by inhalation of drops of infective
material. Signs include a dry, hacking cough, sudden onset
of fever, watery nasal discharge, weakness, stiffness, loss
of appetite and depression. Infection with equine influenza
is rarely fatal but can cause problems such as emphysema,
pneumonia or bronchitis. Equine Herpesvirus (rhinopneumonitis,
rhino, viral abortion) There are 2 types of equine herpesvirus:
EHV-1, which causes respiratory disease (fever, cough, nasal
discharge), reproductive problems (abortion, stillbirth),
and neurological problems (hindlimb weakness, difficulty walking,
sometimes paralysis); and EHV-4, which just causes respiratory
problems and is usually only a problem in younger horses.
Once a horse has been infected with EHV-1, he will always
be a carrier, and the virus may re-activate within the horse
during times of stress. A horse that has been infected with
EHV-4 will always test positive for it also, but usually will
not show clinical signs of it again after the initial infection.
West Nile Virus
Horses get WNV by being bitten by an infected mosquito; most
horses do not show any signs and recover on their own, but
in some horses the infection affects the central nervous system
and causes signs including fever, weakness or paralysis of
the hind limbs, impaired vision, lack of coordination, head
pressing, convulsions, inability to swallow, and coma.
This is a viral infection of the central nervous system, and
although it is not common in horses, rabies can be transmitted
to horses by the bite of an infected animal such as a skunk,
raccoon, fox, dog or bat. Rabies can be transmitted to people.
We recommend that you check with your veterinarian regarding
recommendations for rabies vaccination for your horse.
Strangles (shipping fever)
This contagious respiratory disease is caused by a bacterial
infection. Signs include a fever, thick, yellow, nasal discharge
and swollen, abscessed lymph nodes under the jaws. The infection
is spread by infected material from nasal discharge or abscesses
contaminating stalls, feed troughs, pastures, etc. Young horses
are the most susceptible to strangles and many horses seem
to have a lifetime immunity after recovering from this disease.
Potomac Horse Fever
This disease is a bacterial infection of the blood and tissues
and is thought to be transmitted to horses by arthropod vectors
such as ticks, lice, mites, and fleas. It is much more common
in some areas of the country than others. Signs include a
high fever, depression, decreased gut sounds, and a profuse,
watery diarrhea that can lead to laminitis, colic, dehydration,
shock, and death.
Another common horse condition are worms, although not
technically a disease, they are parasites. Learn more about
horse supplies available to keep your horse healthy.
About the Author
Brent Goodman holds degrees in English from Ripon College,
a Masters of Fine Arts from Purdue University, and has extensive
experience in research communications and educational publishing
across various fields of study. He is currently a Copywriter
Foster & Smith Pet Supplies, the nation's leading online
and catalog pet supplier.