Vaccination – Risk vs Reward

It’s the time of year when thoughts turn to ‘spring vaccinations’ for our horses. We want to protect them from possible life-threatening diseases and keep them healthy. But we also hear about vaccine reactions ranging from painful swellings to more severe reactions, including death. It all can be confusing and overwhelming with so much information and differences of opinion.


Personally, I think of vaccinations as just one way to protect my horses and look at them in the terms of risk vs. reward. In other words, what are the risk factors for my horses having vaccine reactions (long and short term) versus the rewards of using the vaccine for protection? The exposure level of my horse is based on where my horse lives and where my horse travels. How healthy is my horse? A healthier horse tends to be less reactive to vaccination and develop a higher level of protection. Horses that are very old, very young, stressed, or have some kind of chronic illness/condition all have a lower rate of proper response to vaccination. Yet, these are the very ones that are more susceptible to illness!

Also, how effective is that particular vaccine and what is its record of reactions? Respiratory vaccines are notorious for a high level of reactions and have a low protection rate. They tend to lessen symptoms more so than keep the horse from getting sick. Vaccines with a high level of efficacy include tetanus, rabies, and encephalitis. These have been shown to be protective for 3 years or more after initial doses. They have low initial reaction rates – though rabies in small animals can cause long-term issues such as skin and behavioral problems. Strangles, Potomac Fever, and Lyme disease vaccines all have a very high rate of reactions and are mostly used in areas where the diseases are endemic.


Adverse reactions to vaccines can happen anywhere from immediately after administration to up to 30 days after, or more. The risk of reaction increases when multiple vaccines are given at the same time. All vaccine labels read that they are for use in healthy animals only. So it is particularly important that your horse not be vaccinated if he is ill or has a chronic condition such as Cushing’s disease, horses prone to laminitis, tumors, or horses with allergies and even diarrhea!

Reactions range from fever, swelling, and pain at the injection site and lack of appetite to colic, laminitis, purpura, flare ups of chronic disease that were under control, allergies, melanomas, and of course there is always a chance of an immediate severe allergic reaction that can cause death…though this is extremely rare.


There are other ways to keep your horse healthy by supporting their immune system, keeping their stress factors low, keeping their gut happy, and minimizing exposure when possible. Your horse’s living conditions should provide a clean environment with plenty of fresh air, sunshine, clean water, regular exercise including turn out time; and a healthy diet that includes enough food/feeding times to keep food in the gut, yet not so much that your horse is overweight. There are also herbs, nutritionals, essential oils, and homeopathic medications that can help build your horse’s immune system and protect during times of stress or a disease outbreak.

Ultimately it is up to you as an owner to make an informed decision about how best to protect your horse from disease and keep them healthy.