Importance Of Vaccinating Your Horses

By Dr. Kari Vander Werf & Deb Haines


(Note that I am writing this as a Florida veterinarian who also practiced in KS and has seen the devastation of WNV, rabies, tetanus, and most recently (this past week) have had 3 cases of suspected EEE, one so far being positive on testing, first hand. Please, I don’t want to euthanize any more horses for an easily preventable disease!)

Please vaccinate your horse for the core diseases – EEE, WEE, Tetanus, WNV, and Rabies. At. A. Minimum. Please talk to your vet about risk-based vaccines such as PHF, Botulism, EHV 1/4, Strangles, etc.

The encephalitis viruses are devastating. It doesn’t matter if your horse never leaves your farm – guess what? These viruses are DELIVERED to your horse, like a fresh pizza, via mosquitoes. Rabies is in wildlife – have you EVER seen a bat, raccoon, or fox on your farm? Stray cat or dog? They could be rabid. Tetanus is in the environment – it’s everywhere. It doesn’t have to be a rusty nail – any puncture or wound can result in tetanus.

The vaccines for these core diseases are VERY effective if done correctly (boostered first vaccines, yearly to twice yearly afterwards depending on disease and how endemic it is in the area – see the charts below).

Any neurological horse is potentially a rabid horse – rabies can look like anything. It’s “The Great Pretender”. Testing for rabies is compulsory if there has been human exposure to saliva. This involves removal of the brain – there is no other way to test. Do you know how heartbreaking it is to a vet to have to explain that we now need to remove the head of your beloved horse to test it for rabies so that you and your family can be safe?

Please don’t come to this post saying “well they’ve shown vaccines to last for 7 years or longer”. That study was in dogs – dogs are not horses – and is a whole other discussion best left to PVC. They are exposed differently and have different immune systems and sensitivities to certain diseases.

Titers: Titers are challenging and the science, I hope, is improving. We don’t know what protective titer levels are for many of the diseases. It would be near impossible to get a challenge study done for rabies (a study in which you need to give rabies to an animal to see if they are protected at different titer levels – and it wouldn’t be just done in one animal, it would have to be done in many). Titer levels also only measure one arm of the immune system. And that titer would only be a point in time – the antibody levels can wane at variable rates. Could it be done for horses that react to vaccines (there are other things to try in this case) or are in areas of low disease prevalence, etc? Sure. But know that it’s a gamble if you live in an area of high exposure.

Vaccine reactions, ways to prevent: Splitting up the vaccines – every 2-4 weeks – with single antigen to find out which they are reacting to. Changing vaccine manufacturers (each manufacturer uses a different adjuvant and this is usually what the horse reacts to). Ensuring the vaccine is room temp when giving (but not for too long or it expires) – just not straight from the fridge/cooler. Pre-medication with an NSAID. Using other muscles than the neck.

Here are some links for reading:…

AAEP Guidelines:

AAEP Adult Vaccination Chart:

AAEP Foal Vaccination Chart:

Why it’s important to have your veterinarian administer the vaccines:


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