If there were an outbreak of an infectious or zoonotic equine
disease, would you know how to keep you and your horses safe?
Would you know what to do if your horse was exposed or became
ill? While it is rare for humans to contract a disease from a horse, it
is possible. It is therefore very important to know which infectious
diseases are zoonotic diseases and understand how to prevent and
respond to them.
Our common ancestry with animals was recognized in the
nineteenth century by the physician Rudolf Virchow who coined
the term zoonoses—diseases that can be transmitted to humans
from animals. He said, “Between animal and human medicine,
there are no dividing lines—nor should there be.” This common
ancestry means we share much of the same biochemistry and therefore, much of the same susceptibilities. There are many bacteria
and viruses that are infectious between horses such as rotavirus,
Equine Herpesvirus, Equine Influenza, Rhinoviruses, Streptococcus equi, and Rhodococcus equi. However; there are also diseases
that can infect horses and are transmissible to either other horses
or humans (those we consider to be zoonotic diseases). Three of
the most important are salmonellosis, rabies, and leptospirosis.
Diseases transmitted specifically from horses
Salmonellosis is one of the most commonly diagnosed
infectious causes of diarrhea in adult horses, and foals are also
susceptible. Transmission often occurs by ingesting feed or
water contaminated by manure.
Rabies is a viral disease transmitted by contact between the
rabid animal’s saliva into open wounds or mucous membranes.
Often the saliva is delivered via the bite of a rabid animal such
as a skunk, raccoon, or bat. While the incidence of rabies in
horses is relatively low (due to successful vaccination efforts),
the disease is invariably fatal and has considerable public health
Leptospirosis is a potentially fatal bacterial disease that humans and horses can contract through direct or indirect contact
with infected urine, as well as ingestion of contaminated water,
hay, or grain. Leptospirosis is now classified as a re-emerging
infectious disease by the Centers for Disease Control and the
World Health Organization. Leptospirosis in horses has a range
of symptoms including fever, loss of appetite, lethargy, light
sensitivity, abortion, kidney disease, and eye problems such as
swelling, redness, discharge, and cloudiness.
Infectious and Zoonotic Disease:
How Can You Prevent the Spread?
By Rachel Wiesen, DVM Student (Class of 2014)
Edited by Stacy H. Tinkler DVM, MPH, Dipl ACVIM, Purdue Equine Community Practice
How to prevent infectious
and zoonotic disease
on your farm
Awareness is the first necessary
element for prevention. As an
owner, not only can you dramatically minimize introduction of
and spread of many diseases, you can contribute to a longer and
better quality of life for you and your horses by following this
simple step-by-step checklist:
1) Get Informed
A. Turn to a reliable source such as your veterinarian,, your local
veterinary teaching hospital, or appropriate state/federal officials
for accurate information and advice about infectious and zoonotic
diseases, routine vaccinations, and preventive medicine.
2) Create a Biosecurity Plan/Avoid Exposure
A. A biosecurity plan is a set of control measures designed to
reduce the spread of infectious diseases. Having one in place will
decrease the chances that your horse will contract an infectious
disease. Consult with your veterinarian to create a biosecurity plan
and vaccination program. This should include fly, rodent, bird,
and pest control, as well as traffic control on the farm.
B. Don’t take your horse anywhere where horses are known to
3) Monitor/Isolate Any Exposed and Sick Horses
A. If your horse becomes exposed to a contagious disease, isolate
him for at least 14 days (30 days is ideal) in a stall/pen at least
30-40 feet away from other horses. Monitor temperature every
day. Talk to your veterinarian on what to look for depending on
what disease your horse was exposed to.
B. Isolate sick, new, and horses returning from a show or event
for a minimum of 14 days. Only mix them with other horses if
they have not had a fever and have remained healthy during that
time. This will help reduce the risk of introducing any infectious
disease to the other resident horses.
C. If your horse becomes sick, work with your veterinarian to
provide appropriate care while keeping the sick animal isolated
from other horses. A separate barn is ideal, or you can designate
a quarantine area at the far end of your barn away from the main
traffic area and other horses.
D. Immediately isolate any horse with nasal discharge, cough,
fever, or diarrhea.