It is now August, which means Fall vaccines are upon us here in Southern California. If you haven’t already made an appointment with your veterinarian for a semi-annual wellness exam and vaccines, this should give you an idea of exactly what to expect when discussing your options.
First, vaccines are either a live modified or killed version of the disease we are protecting against administered in an adjuvant to prepare the body with a defense mechanism should they ever be exposed to the disease in its natural state. This way, when a horse gets bit by a mosquito carrying West Nile, the body will recognize it and be able to defend itself. Just like with people, if a horse has a bit of a reaction to the vaccine (like lethargy, mild fever, localized swelling, loose stool, etc) it’s not because they’ve contracted the vaccine, but because their immune system is doing it’s job to protect the body. If we know ahead of time that a horse has a history of reacting to vaccines, we can premedicate them with various injections like Bute, Banamine, Diphenhydramine, Dexamethasone to give the body a boost in its response. We can also separate vaccines by a couple of weeks to decrease the likelihood of a reaction.
When talking about vaccines with your vet, they will likely mention that there are “core” vaccines and “lifestyle” vaccines. What this means is that the “lifestyle” vaccines are optional based on the area you live in and your horse’s likelihood of being exposed to the disease. The core vaccines here in the united states are:
Vaccine | How It’s Spread | How Often (Minimum) |
Eastern & Western Encephalomyelitis | Mosquitoes | Every Spring |
West Nile Virus | Mosquitoes | Every Spring |
Rabies | Any mammal, most commonly skunks or bats | Annually |
Tetanus | Penetrating Injury | Annually |
How often these vaccines need to be given depends on what part of the country you live in (the charts above and below represent what we do here in Southern California). You may be thinking, “My dog only needs his vaccines once every three years. Do I really need to give my horse vaccines this often?”. In short, yes. Generally, horses are not as good as dogs and cats are at protecting themselves against disease and they get exposed much more frequently. Since Rabies is a zoonotic disease that people can die from, we tend to stay on top of that the most, but please still consult your local veterinarian for their recommendation.
Here are the lifestyle vaccines:
Vaccine | How It’s Spread | How Often |
Influenza & Rhinopneumonitis (Flu/Rhino) | Nose to Nose contact, Coughing, Shared Equipment | Every 6 months |
Strangles | Horses, Equipment, Handler Clothing | Annually (generally unnecessary in CA) |
Potomac Horse Fever | Snails and water | Varies (unnecessary in CA) |
Botulism | Bacteria in hay | Annually (unnecessary in CA) |
Flu/Rhino is required by most of the United States Equestrian Federation horse shows, all Olympic level shows, and horseracing events. Equine Influenza can lead to pneumonia just like it does in people, but there are different strains which change on a regular basis. Strangles is more practitioner dependent meaning your veterinarian will decide whether or not it is worth it for you to have your horse protected against it. Here, we currently don’t see it enough for the benefit of the vaccine to outweigh the possible reactions to the vaccine which can include purpura hemorrhagica causing skin sloughing in severe cases. Potomac Horse Fever is most commonly only seen in horses living near the Potomac River Valley (Maryland, Pennsylvania, Virginia, and West Virignia) whereas Botulism is more common in the Northeast part of the United States and is the worst during the winter.
You may have also heard some people mention the word “titer”. Although I haven’t seen many people in the horse world decide to run titer tests on their horses, it is a little more common with dogs and can be a useful tool when deciding whether or not your animal really needs another vaccine. A titer is a blood test that determines if a horse has enough antibodies to fight off a disease. Titer tests are available for EWE, WNV, and Rabies, so you may consider doing a test instead of administering the vaccine again if your horse has reacted strongly to one of them in the past.
Another big tip I’d like to share with everyone is to please please please buy your vaccines through your veterinarian, not the feed store. Almost all vaccines are guaranteed by their manufacturer meaning that if your horse gets sick from something it has been vaccinated against, the manufacturing company will pay for the treatment but only if the vaccine has been administered by a veterinarian because they know the product has been handled properly. When you buy a vaccine from a feed store, not only do you lose out on that coverage, but you are taking a gamble on whether or not the feed store employees have properly handled their vaccine shipments. If the case was not put in a refrigerator immediately upon delivery, even if it sat out for only a few minutes, the vaccine becomes completely useless and there's no way to tell by looking at it if it's still good.
We also want to make sure not to give vaccines to a sick horse because their immune system will not respond appropriately. This is why it is necessary for your veterinarian to examine your animals when you ask them to administer a vaccine. If you do decide to DIY it, you’ll want to make sure all of your horse’s vitals are within normal limits first.
It is also important to note that vaccination frequency depends on your horse’s life stage as well. Young horses and senior horses may need to have additional boosters if their immune systems are not functioning at 100%. Pregnant mares have a completely different vaccine schedule while they are pregnant. We will vaccinate them for Rhino at either 3, 5, and 7 months or 5, 7, and 9 months to reduce abortion rates and administer all of their regular vaccines (independent of their previous schedule) at 10 months to make sure their colostrum carries antibodies for each disease to provide protection for the foal until they are ready to get their own vaccines.
Here is a link to the American Association of Equine Practitioners' vaccine guidelines for adult horses or broodmares and their guidelines for foals.
If you want to learn more about general horse health and enjoy listening to podcasts, I highly recommend starting on "Straight from the Horse Doctor's Mouth" with Erica Lacher, DVM :
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