Equine Vet Services



Vaccination Chart At Bottom Of Page

What Is A Vaccination (Immunization)
Vaccination involves the injection (with a sterile syringe and needle) of bacteria or viruses that are inactivated or modified to avoid
causing actual disease in the horse. Two or more doses are usually needed to initiate an adequate immune response.
Once the immunization procedure is completed, the protective antibodies in the blood stand guard against the invasion of specific
diseases. Over time, however, these antibodies gradually decline. Therefore, a booster shot is needed at regular intervals. Protection
against some diseases such as tetanus and rabies can be accomplished by boostering once a year. Others require more frequent
intervals to provide adequate protection.

Why The Need To Vaccinate?
It is up to you to protect your horse against contagious diseases and parasites.  Immunizations easily and effectively protect your
horse from the ravages of disease.  Vaccinations place a protective barrier between your horse and a whole list of problems: tetanus,
EPM, West Nile, encephalomyelitis (sleeping sickness), influenza, rhinopneumonitis, rabies, strangles and others.

A good immunization program is essential to responsible horse ownership, but just as in humans, vaccination does not guarantee
100% protection. In some situations, immunization may decrease the severity of disease but not prevent it completely. This is due
to many complicated scientific reasons, such as differences in the type or severity of some diseases (such as influenza).

Vaccinations are also a vital part of proper equine management. If used in a program that includes regular deworming, an ample supply
of clean water, a good nutrition program, and a safe environment, you and your equine will be all set to enjoy many happy, healthy,
productive years together.

What Vaccinations Do You Need?
Equine Vet Service can help you design and maintain a health management program to reduce exposure to infectious disease agents
in your horse's environment and lessen the incidence of illness. 
The specific immunizations needed by a particular horse or horses depend upon several factors: environment, age, use, exposure risk,
geographic location, and general management. We can help you determine the vaccination program best suited to your horse's
individual needs.

The following diseases are those most often vaccinated against. Your horse(s) may or may not need all of them.

Sometimes called "lockjaw," tetanus is caused by toxin-producing bacteria present in the intestinal tract of many animals and found
in abundance in the soil where horses live. Its spores can exist for years. Symptoms include muscle stiffness and rigidity, flared nostrils,
hypersensitivity, the legs stiffly held in a locked position as the disease progresses, muscles in the jaw and face stiffen, preventing the
animal from eating or drinking. More than 80 percent of affected horses die. Luckily, this disease is not contagious. Contamination is
through wounds, especially in the case of lacerations and deep punctures.  The spores enter the body through wounds, lacerations, or
the umbilicus of newborn foals.  
Horses are particularly susceptible to the paralyzing toxin produced by the bacterium Clostridium tenani
in a wound.  In addition, areas where horses are located have high levels of the bacterial spores.

All horses should be immunized annually against tetanus. Additional boosters for mares and foals may be recommended by your
veterinarian. Available vaccines are inexpensive, safe, and provide good protection.
Of all the vaccinations that horses receive, tetanus
toxoid is by far the most important.  The vaccination is highly efficacious in preventing the disease.

There is also a tetanus antitoxin that only offers protection for up to three weeks, and it has the potential to cause liver disease.

Equine Encephalomyelitis:   
More commonly known as "sleeping sickness," this disease is caused by the Western Equine Encephalomyelitis (WEE) virus or
the Eastern version (EEE). WEE has been noted throughout North America, while EEE appears in the east and southeast.
VEE, the Venezuelan variety, has not been seen in the United States for many years. However, a recent outbreak of VEE occurred
in Mexico. Sleeping sickness is most often transmitted by mosquitos, after the insects have acquired the virus from birds and rodents.
Humans also are susceptible when bitten by an infected mosquito, but direct horse-to-horse or horse-to-human transmission is
very rare.
Symptoms vary widely, but all result from the degeneration of the brain. Early signs include fever, depression, and appetite loss.
Later, a horse might stagger when it walks, and paralysis develops in later stages.
About 50 percent of horses infected with WEE die, and the death rate is 70 to 90 percent of animals infected with EEE or VEE.
All horses need an EEE and WEE vaccine at least annually. Pregnant mares and foals may require additional vaccinations.
The best time to vaccinate is spring, before the mosquitos become active.
The vaccination schedule is the same as tetanus toxoid,
and is typically given at the same time.
In the South and West, some veterinarians choose to add a booster shot in the fall to ensure
extra protection all year-round.


Equine Influenza: 
This respiratory disease can often affect large numbers of horses, but is usually not fatal. 
Influenza is one of the most common respiratory diseases in the equine. The risk of influenza is higher for young horses than older
The virus is highly contagious and can be transmitted by the air  from equine to equine over distances as far as 30 yards, for
example, by snorting or coughing.
Signs to watch for are similar to those in a human with a cold, i.e., dry cough, nasal discharge, fever, depression, and loss of appetite.
With proper care, most equines recover in about 10 days. Some, however, may show symptoms for weeks, especially if put back to
work too soon. Influenza is not only expensive to treat, but results in a lot of "down time" and indirect financial loss, not to mention
discomfort to your equine.
Unfortunately, influenza viruses constantly change in an effort to bypass the horse's immune defense. Therefore, duration of protection
is short-lived and revaccination is recommended.
Since the virus can mutate frequently, vaccinations should contain the most recent
Not all equines need influenza vaccination. However, animals that travel or are exposed to other equines should be regularly
|immunized against influenza. Follow your veterinarian's advice as to whether your equine needs influenza vaccine.

Rotavirus causes diarrhea in foals anywhere between 12 hours of age to five months of age.
The vaccine has some efficacy, therefore mares should be vaccinated at eight, nine, and 10 months of gestation.
Foals can be vaccinated at a young age.

Equine Rhinopneumonitis: 
Caused by a herpesvirus (similar to the human common cold), this disease, like influenza, is rarely fatal, but can cause the horse
to be very sick for a prolonged period of time.  And like influenza, vaccination cannot guarantee that the horse will not contract the
disease.   However, horses that have been vaccinated most often demonstrate much milder symptoms that those that have not been

Two distinct viruses, equine herpesvirus type 1 (EHV-1) and equine herpesvirus type 4 (EHV-4),
cause two different diseases, both of which are known as rhinopneumonitis. Both cause respiratory tract problems,
and EHV-1 may also cause abortion, foal death, and paralysis.

Infected horses may be feverish and lethargic, and may lose appetite and experience nasal discharge and a cough.
Young equines suffer most from respiratory tract infections and may develop pneumonia secondary to EHV-1.
Rhinopneumonitis is spread by aerosol and by direct contact with secretions, utensils, or drinking water. Virus may be present
but unapparent in carrier animals.

All pregnant mares must be immunized. Foals, weanlings, yearlings, and young equines under stress also should be vaccinated.
Immune protection is short. Therefore, pregnant mares are vaccinated at least during the 5th, 7th, and 9th months of gestation,

Vaccination of foals is usually done at greater than six months of age with 2-3 boosters 3-4 weeks apart. 
Adults should be vaccinated 1-4 times per year depending upon risk factors.


This upper respiratory disease, caused by Streptococcus equi, is highly contagious when present on a farm. 
Horses could carry
the organism in the guttural pouch for at least two years.
The disease is characterized by large abscesses under the throat which
can sometimes take weeks or months to resolve. 
There may be some side effects associated with vaccination; therefore, it is important to discuss the risks versus benefits of
vaccination with your veterinarian.
The Strangles vaccine is not a routine part of the vaccination program unless there is a problem
with strangles in the area. This is due to a high risk of local reaction and other side effects with the injectable vaccine. The vaccine
does not provide long-term immunity, and it should not be given with other shots.
Foals may be vaccinated at 2-3 months with a booster 2-3 weeks later.

Rabies is a frightening disease which is more common in some areas than others. Equines are infected infrequently, but death
always occurs.
Rabies has a high level of public significance as human exposure can be devastating. Rabies can be transmitted
from equines to humans,
 although there are no reported cases in humans from equine exposure. The rabies vaccine is a “must-do.”

The primary carriers of rabies in Kentucky are skunks and raccoons.  But even horses housed in the city are not necessarily protected
as rabies can be carried by dogs, cats, squirrels or any warm blooded mammal.
Foals may be vaccinated at 4 months of age with a booster 3-4 weeks later. 
 The rabies shot is given in two initial doses four weeks
apart followed by yearly boosters.

Vaccination of pregnant mares is not recommended as safety studies have not been performed.

This disease is found mainly in the mid-Atlantic states, and vaccination might not be indicated in your area. Botulism can be fatal
and is very expensive to treat.
It causes a flaccid paralysis, and is often the result of horses eating around the carcasses of animals
that have died.  It has also been cited as being found in newly disturbed earth and in alfalfa hay. 
Botulism is known as "shaker foal
syndrome" in young horses. Botulism in adult horses, "forage poisoning," also can be fatal.
Foals are most commonly affected,
but horses of all ages are at risk.
Consult with your veterinarian for his or her recommendations in your area.
Vaccines are not available for all types of botulism, but
pregnant mares can be vaccinated in endemic areas.

Equine Viral Arteritis (EVA):
EVA is a contagious, sexually transmitted disease that can cause abortion, edema (fluid swelling), and various other symptoms.
It is a complicated disease which can result in some breeding restrictions and export problems.
Vaccination is very effective and is
required annually by law for Thoroughbred stallions in Kentucky, including teasers. Mares sent to a positive stallion should be vaccinated.

Because the vaccine is a modified live vaccine, it is possible for a vaccinated animal to pass the disease on by respiratory droplet
infection to other horses in close proximity for a period of three to four weeks. Consequently, all horses in the same barn should be
vaccinated at the same time and quarantined for three to four weeks.
A blood test should be done before the first vaccination to differentiate a positive result from exposure vs. vaccination. Vaccination once
per year should be sufficient.
Follow your veterinarian's recommendations. Currently, only certain breeding stock is being routinely
vaccinated under specific state regulations.  These regulations should be strictly adhered to or the horse may face serious obstacles
to a breeding career.


Potomac Horse Fever:
This disease, which causes severe diarrhea and death, is not currently in this region. However, horses planning to travel to the
east coast, or other areas where the disease is prevalent, should be vaccinated.  Foals may be vaccinated at 4-6 months of age with
2 doses 3-4 weeks apart. 
Boosters may be given twice a year for those horses in an endemic area.
One third of affected horses die. Contact your veterinarian
for further advice..

West Nile Virus:
The West Nile Virus affects a number of different species, including man, horses, and birds. It is most commonly spread by the bite of
a mosquitoes, no direct horse to horse or horse to man transmissions are known at this time.  Although it is rarely fatal in humans,
mortality rates in horses can reach up to 40 percent.  Even though the winter will kill the present population of mosquitoes, the disease
can remain endemic in an area. 
Early vaccination, before there is a wide outbreak, is recommended.  The vaccination is given initially with a booster 3-6 weeks later,
and then annually thereafter. In places with a mild winter boosters could also be given in the fall.

Equine Protozoal Myeloencephalitis (EPM)
EPM is a debilitating neurologic disease of horses. It can affect the brain, brainstem, spinal cord or any combination of these three
areas of the central nervous system. The disease may present itself with a variety of different clinical signs, dependent on the location
of the damage caused by the organism within the CNS.
 Although the incidence of EPM is not high in the population of horses,
those horses affected are often severely affected.
The causative agent of EPM has been identified as Sarcocystis neurona.
Clinical signs are vague, but can include weakness, lameness, incoordination, difficulty moving (especially in hindquarters), or in
rising from lying down. Signs can also include seizures, weight loss, blindness, loss of balance, head shaking and inappropriate

Possum feces are the source of the infection for horses. Possums acquire the infection by eating infected birds. Horses are then
affected by eating pasture, hay, grain, or water contaminated with possum feces.

The vaccine has been demonstrated to produce high levels of antibodies against the Protozoa Sarcocystis neurona.  In vitro tests
have shown that the antibodies produced have been effective against the organism. Foals 4 months or over may be vaccinated and follow
with a booster 4 weeks later. Annual revaccination is recommended.

Foal Vaccinations
Foals are born immunocompetent, which means they have the ability for a normal immune response. Therefore, if a mare is not vaccinated,
then a foal can be vaccinated at any time. However, if a mare is vaccinated, then she can pass along her antibodies in the colostrum
(first milk). Adequate colostrum intake is essential. Sometimes if vaccines are administered to foals too early they interfere with colostral
antibodies. Today, vaccine recommendations for young horses have been pushed back, with each vaccine having a different timing for the
initial dosing series.


The schedule below is a suggested vaccination schedule and is based on
generally accepted veterinary practices.
Infectious disease control programs in conjunction with vaccinations are important in
maximizing the health, productivity and performance of your horse. 

Schedules for stallions should be consistent with the vaccination program
of the adult horse population on the farm and modified according to risk.

You should consult with your veterinarian regarding a vaccination program that will
provide the most benefits for your horse.

EEE=eastern equine encephalomyelitis, WEE=western equine encephalomyelitis,
 VEE=Venezuelan equine encephalomyelitis; EHV-1=equine herpes virus type;




Performance Horses

Pleasure Horses



Tetanus toxoid

(Note:  Tetanus Anti-toxin, often given at birth, does not invoke long term immunity in foals.)

From nonvaccinated mare: First dose: 3 to 4 months Second dose: 4 to 5 months

From vaccinated mare: First dose: 6 months Second dose: 7 months Third dose: 8 to 9 months




Annual, 4 to 6 weeks prepartum

Booster at time of penetrating injury or surgery if last dose not administered within 6 months



EEE: (in high-risk areas) First dose: 3 to 4 months Second dose: 4 to 5 months Third dose: 8 to 9 months

WEE, EEE (in low-risk areas) and VEE: From nonvaccinated mare: First dose: 3 to 4 months Second dose: 4 to 5 months Third dose: 5 to 6 months

 From vaccinated mare: First dose: 6 months Second dose: 7 months Third dose: 8 months

Annual, spring

Annual, spring

Annual, spring

Annual, spring

Annual, spring

Annual, spring

Annual, 4 to 6 weeks prepartum

Annual, 4 to 6 weeks prepartum

In endemic areas booster EEE and WEE every 6 months; VEE only needed when threat of exposure; VEE may only be available as a combination vaccine with EEE and WEE.


Inactivated injectable: From nonvaccinated mare: First dose: 6 months Second dose: 7 months Third dose: 8 months Then at 3-month intervals

From vaccinated mare: First dose: 9 months Second dose: 10 months Third dose: 11 to 12 months Then at 3-month intervals

Every 3 to 4 months

Every 3 to 4 months

Annual with added boosters prior to likely exposure

At least semiannual, with 1 booster 4 to 6 weeks prepartum

A series of at least 3 doses is recommended for primary immunization of foals.

(EHV-1 and EHV-4)

First dose: 4 to 6 months
Second dose: 5 to 7 months
Third dose: 6 to 8 months
Then at 3-month intervals


Every 3 to 4 months

Optional: semiannual if elected


Annual with added boosters prior to likely exposure


Fifth, seventh, ninth month of gestation (inactivated EHV-1 vaccine);
optional dose at third month of gestation.

Vaccination of mares before breeding and 4
to 6 weeks prepartum is suggested. Breeding stallions should be
vaccinated before
the breeding season and semiannually


Injectable: First dose: 4 to 6 months Second dose: 5 to 7 months Third dose: 7 to 8 months (depending on the product used) Fourth dose: 12 months




Optional: semi-annual if risk is high

Optional: semi-annual if risk is high

Semi-annual with 1 dose of inactivated M-protein vaccine 4 to 6 weeks prepartum

Vaccines containing M-protein extract may be less reactive than whole-cell vaccines. Use when endemic conditions exist or risk is high.


Foals born to non-vaccinated mares: First dose: 3 to 4 months Second dose: 12 months

 Foals born to vaccinated mares: First dose: 6 months Second dose 7 months Third dose: 12 months




Annual, before breeding

Vaccination recommended in endemic areas. Do not use modified-live-virus vaccines in horses.

Potomac Horse Fever

First dose: 5 to 6 months Second dose: 6 to 7 months




Semi-annual with 1 dose 4 to 6 weeks prepartum

Booster during May to June in endemic areas.


Foal from vaccinated mare: 3 dose series of toxoid at 30-day intervals starting at 2 to 3 months-of-age

Foal from non-vaccinated mare: see comments

Not applicable

Not applicable

Not applicable

Mares should be vaccinated at eight, nine, and 10 months gestation.

Only in endemic areas. A third dose administered 4 to 6 weeks after the second dose may improve the response of foals to primary immunization.

Foal from non-vaccinated mare may benefit from: 10 toxoid at 2,4 and 8 weeks-of-age; 2) transfusion of plasma from vaccinated horse; or 3) antitoxin. Efficacy needs further study.

Equine Viral Arteritis

Intact colts intended to be breeding stallions: One dose at 6 to 12 months-of-age

Annual for colts intended to be breeding stallions

Annual for colts intended to be breeding stallions

Annual for colts intended to be breeding stallions

Annual for seronegative, open mares before breeding to carrier stallions; isolate mares for 21 days after breeding to carrier stallion

Annual for breeding stallions and teasers, 28 days before start of breeding season; virus may be shed in semen for up to 21 days. Vaccinated mares do not develop clinical signs even though they become transiently infected and may shed virus for a short time.

Rotavirus A

Little value to vaccinate foal because insufficient time to develop antibodies to protect during susceptible age

Not applicable

Not applicable

Not applicable

Vaccinate mares at 8, 9 and 10 months of gestation, each pregnancy. Passive transfer of colostral antibodies aid in prevention of rotaviral diarrhea in foals.

Check concentrations of immunoglobulins in foal to be assured that there is no failure of passive transfer.

West Nile Virus  



Annual, spring



Annual, spring Annual, spring  

Initial dose followed by a second dose in 3-6 weeks with semi-annual or annual boosters.

A third initial dose is ONLY needed if the second booster dose was given after the 6 week period following the first dose. This dose should also be given in the 3-6 weeks period.

Have vaccine series completed
at least one month prior to the mosquito season

EPM   Annual, spring Annual, spring Annual, spring   Initial dose followed by a second dose in 3-6 weeks with semi-annual or annual boosters.


Equine Veterinary Service
4025 Coleman Cut Road   Paducah, KY. 42001
Phone (270) 554-6601     Fax (270) 554-0089

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