Attitudes about vaccination have changed in the last 20 years. Vaccines were once seen as the best way to prevent many diseases in horses, and their disadvantages weren’t often considered. Now we are looking harder at vaccines and understanding the risks of over-vaccination. Ideally, vaccination protocols should be tailored to the individual horse. The vaccines for that horse can then be based on likely exposure to the disease in question, and his ability to mount an adequate response. Titers may be used to assess response to previous vaccines or natural exposure. However, the decision to vaccinate is sometimes forced on us since many boarding facilities and horse shows require horses to receive vaccines.


If you are facing the need to vaccinate your horse, there are things you can do to make the process successful, with minimal negative effects. Vaccines are designed to be given to healthy horses; many of the negative effects occur in animals that are not in full health. The goal of a vaccine is to stimulate your horse’s immune system to mount an immune response to the injected disease antigen, so he will quickly respond in the case of a natural infection. If the horse does not have a strong immune system, the vaccine will not be protective. Ultimately, the protection from disease must come from your horse’s response to the vaccine, not the vaccine itself.

Chronic conditions such as laminitis, uveitis, allergies, tendency to colic, cancerous tumors and old age are all signs that a horse is not healthy enough to be given vaccines. Cushing’s and insulin-resistant horses may also react poorly to vaccination. These conditions should be resolved before vaccines are given.


Inadequate nutrition can also weaken your horse’s immune system. Diets low in trace minerals, such as zinc, can result in a weak immune system. Horses that are thin and undernourished should be allowed to gain condition before being vaccinated. If possible, hay
should be tested to make sure it provides adequate levels of protein and minerals to support a healthy immune system in your horse. If your hay is low in minerals, then a whole food (such as blue-green algae) may provide the missing trace elements.

Stress is probably one of the biggest enemies of your horse’s immune system. Weaning, moving from one barn to another, hard training, showing, inclement weather and poor herd dynamics can all cause enough stress to lower a horse’s ability to respond well to vaccines. It is best to vaccinate your horse at a time when he can be in his normal surroundings, have a week or so off from training, and when weather conditions are not extreme.

Vaccines can help prevent disease in healthy horses, but they are not without possible negative effects. Unhealthy horses should not be vaccinated. Healthy horses can be assisted to respond well to vaccines, and treatments can be given to counter bad reactions. Use titers to avoid additional vaccines whenever possible. Kansas State University will do rabies titers and the USDA lab will test for Eastern, Western, Venezuelan and West Nile encephalitis. Your vet should be able to do these tests if you ask for them.

Madalyn Ward is trained in Veterinary Homeopathy, Acupuncture, Bowen Therapy, Network Chiropractic and Equine Osteopathy. Memberships include the American Veterinary Medical Association, American Association of Equine Practitioners and American Holistic Veterinary Medical Association. She has authored three books, Holistic Horsekeeping, Horse Harmony, Understanding Horse Types and Temperaments and Horse Harmony Five Element Feeding Guide.,