Which Diseases Should I Vaccinate My Horses Against?

In accordance with recommendations by the American Association of Equine Practitioners (AAEP), The Equine Center suggests vaccination against the following 9 diseases (representing 6 vaccinations).

RABIES – Rabies is a non-curable, fatal disease that can be transmitted from horse to human. San Luis Obispo County is a hot bed for rabies, frequently number one in the State of California in incidence. Anyone who has seen a skunk during the daytime has seen a rabid animal. Since horses usually exhibit signs such as excess drooling and in coordination, dental abnormalities are often suspected first. Frequently by the time rabies is determined many people have been exposed. Horses and cattle have the highest incidence of rabies in livestock animals. The Department of Animal Regulation treats horse and dog bites under the same policy because the consequences are the same. This means that if your horse bites someone and you cannot document rabies vaccination Animal Regulation will recommend your horse be euthanised and tested for rabies. Your only other option is to confine your horse to a strict 6-month quarantine. Because of the risk factor to human and animal health, the high incidence of rabid wildlife in this area, and the availability of safe and effective vaccines we strongly recommend vaccination against rabies. Foals are given a series of two injections 3-4 weeks apart beginning at 6 months of age. Adults are vaccinated annually.  The Equine Center recommends Merials Imrab-3 and uses for all of its herd health needs.

ENCEPHALITIS (Sleeping Sickness) – Encephalitis is a viral disease that attacks the brain in both people and horses. It is harbored in the wild bird population and during the summer months is spread by mosquitoes. There are three forms; Venezuelan (VEE), Eastern (EEE) and Western (WEE), all of which can be vaccinated against. A fourth form known as West Nile Virus (WNV) has caused death in horses and humans in New England and New York in 1999. In 2000 and 2001 the disease re-emerged in the eastern half of the US killing several horses and at least three humans. As of September 2001 a vaccine for the vaccination of horses has become available and approved for use by the California State Veterinarian’s office. Although risk is not high on the Central Coast, outbreaks of encephalitis have been reported in this county in the late ‘70s. It is believed that West Nile Virus will enter the state in either 2002 or 2003. Because of the public health threat, and ease of vaccination, we recommend inoculation against all four forms of encephalitis. Foals are given a series of 3 vaccines, 3-4 weeks apart beginning at 6 months of age. Adults are vaccinated annually.

TETANUS (Lockjaw) – Tetanus disease is the result of a toxin produced when a bacterium enters an animal’s body through a puncture wound. This bacterium is found in virtually every type of soil on the Central Coast. The toxin causes paralysis and loss of control of the nervous system, frequently leading to death. Although a safe and effective vaccine has been available for many years, our practice still occasionally sees a case of Tetanus in unvaccinated horses that have received a puncture wound. Even if your horse does survive tetanus, he/she will suffer a painful illness and you will incur an expensive course of treatment. Foals are given a series of three vaccines 3-4 weeks apart beginning at 6 months of age. Adults are vaccinated annually.

INFLUENZA (Flu) – Influenza is a highly contagious disease caused by one of several strains of a virus that attacks the mid and lower respiratory system. Influenza spreads rapidly because the virus is transmitted through airborne contamination. Infected horses become quite ill for several days, and will cough for up to three weeks. Yearlings, two-year olds and aged horses frequently develop secondary bronchitis and pneumonia, requiring expensive courses of antibiotics and other medication. On the Central Coast this disease is seen most commonly in early fall as the futurity season begins. During this time horses that travel the show circuits become stressed and susceptible to the disease. These horses then return to their barns and infect other horses. Although flu vaccines are given more often than other vaccines in order to maintain protection, they are both safe and effective. A new intra-nasal vaccine is now also available. While intramuscular injections raise the level of resistance throughout your horse’s entire immune system, the intra-nasal vaccination is applied directly into the upper airway where the virus attempts to enter your horse’s body.  Local vaccination offers the horse additional immunity in the upper airway before the virus gets a chance to enter your horses system. We have vaccinated several horses that have subsequently gone to shows where respiratory disease was present. None of these horses became ill. The additional advantage of this vaccine is that it does not require intramuscular injection, thereby decreasing the number of vaccination reactions. It is expected that in 2002 a combination Flu and Rhino vaccine for intra-nasal use will be available as well. Foals are given a series of three of the intramuscular vaccines at 3-4 week intervals beginning at 6-9 months of age, and the intranasal form at 11 months of age. Adults are vaccinated quarterly, usually alternating the intramuscular and intranasal forms of the vaccine.

RHINOPNEUMONITIS (Rhino) – This disease is caused by a herpes virus. There are four forms of the disease syndrome; Venereal, Neurologic, Respiratory, and Abortion. Vaccination is available for the Respiratory and Abortion forms. The respiratory form differs in symptoms from influenza in that the virus attacks mostly the upper airways. The first symptoms are frequently depression and an elevated temperature followed by runny eyes and nose. The abortion form frequently shows no outward symptoms at all until mid to late term pregnant mares begin to abort their fetuses. The vaccines are safe and effective, but adults require vaccination 2-4 times per year in order to insure protection. Foals receive a series of three vaccines at 3-4 week intervals beginning at 4-6 months of age. An intra-nasal form of the vaccine, in combination with Flu, is expected to be available in 2002.

STRANGLES (Strep, Distemper) – This is a highly contagious respiratory disease affecting primarily yearlings and two year-olds, but can effect all age groups. It usually causes large abscesses under the jaw producing pain, discomfort and weight loss. Occasionally an internal, life-threatening form of the abscesses also occurs. Even vaccinated horses may show signs of the disease.  Strangles is frequently seen on the Central Coast during the summer months. We recommend vaccination as part of your spring inoculations in some situations. Please consult with us as to whether vaccination is appropriate in your situation. Foals are vaccinated beginning at 4-6 months of age with an initial series of three injections 3-4 weeks apart. Adults are vaccinated 1-2 times per year depending on the risk of the disease

POTOMAC HORSE FEVER (PHF) – This disease is a cause of colic and fatal diarrhea syndromes, and more recently has been associated with a laminitis (Founder) syndrome seen in pastured horses in summer. Although reports of PHF on Central Coast horses are rare, it is seen frequently in parts of Northern California and especially Oregon. New research by The University of California at Davis shows that fresh water snails carry the organism that transmits the infective form of the disease. Horses most likely to show the laminitis form of the disease are located near creeks or streams, or spend time on irrigated pastures - all common conditions on the Central Coast. Because of our proximity to areas that have encountered PHF, the prevalence of conditions where the organism thrives, and the seasonal incidence of the disease, we recommend vaccination as part of your spring inoculation series. Foals receive a series of 3 vaccines 3-4 weeks apart beginning at 3-5 months of age. Adults are vaccinated annually.

The infectious diseases explained above represent those we recommend inoculation against for horses living on the Central Coast. There are several other disease entities for which vaccination is available for horses traveling to other regions of the country where the threat of those diseases exists. If you plan to travel outside the western U.S. please contact our office for recommendations on any additional inoculations, which your horse may require.

For more free health records or educational brochures on a variety of topics relevant to your horse, please contact us at The Equine Center (805) 541-6367.