Equine Vaccines: An Individualized, Informed Approach for Your Horse

By KC Equine Wellness

As we move into spring, it’s a good time to pause and consdier how we approach vaccines. This time of year often brings up the same questions for many owners—what they’re vaccinating for, what the real risks are, and how those decisions are being made. It’s easy to feel unsure or simply follow whatever is presented as a standard protocol, especially when the season gets busy and everyone seems to be doing the same thing. But spring doesn’t have to feel like a checklist or a rush. It can be a thoughtful opportunity to look at your horse’s actual exposure, lifestyle, and health history, and to make choices that feel appropriate rather than protocol.

Working with a wide range of horses across different disciplines and health backgrounds, I’ve seen how individual responses to vaccines and how they vary more than many people realize. Some horses handle them okay, while others show reactions that are immediate, delayed, or subtle enough that they’re easy to miss. These patterns have become more noticeable over the past few years, and they highlight why a one‑size‑fits‑all approach doesn’t always serve every horse well. My intention is to support owners in making informed, confident decisions that respect each horse’s unique needs, sensitivities, and overall health picture. Spring is a good time to slow down, ask questions, and ensure the plan you follow truly aligns with your horse’s wellbeing.

Your horse is an individual. Their vaccine plan should be too.

Why We Need to Rethink “Standard Protocols”

What I find consistently is that most owners don’t actually know what they are vaccinating for or why. Vaccines are often given simply because it’s “standard protocol,” regardless of the horse’s age, health status, history, or risk level. But horses are suffering under this one‑size‑fits‑all approach, and it’s time we start looking at each horse as an individual. Vaccine schedules are not based on how long immunity actually lasts; they are based on the fact that immunity has been tested for a period of time, often a year, not that it expires at one year. In dogs, research is already showing that core vaccines last far longer than annual schedules suggest, and similar conversations are beginning in the equine world. 

Before vaccinating, it’s worth asking what diseases are actually present in your area, what your horse’s true exposure level is, what the risks of the disease itself are, whether titers are an option, and what is mandatory versus optional. Most importantly—are you making an intentional decision, or simply following routine?

Before You Vaccinate: Key Questions to Consider

These are the same questions I walk clients through every year, because thoughtful decision‑making starts with understanding your horse’s true risks, health status, and history. The first step is determining whether the diseases you’re vaccinating for are actually present in your region. If a disease isn’t circulating locally, the real‑world risk may be extremely low.

Next, consider your horse’s actual exposure. Horses who travel, show, or live in busy lesson barns encounter very different risks than retired horses or those in closed, consistent herds. Then I look at the severity of the illness itself: if a horse becomes sick, is it typically fatal, or is their immune system generally capable of handling it?

When reviewing statistics—especially mortality rates—I also look at the horses behind those numbers. Were they healthy? What was their age? These details matter. This is the level of nuance I bring into every risk assessment to make informed, confident decisions. 

Your horse’s current health status is also a major factor. Vaccination should be approached with caution in horses with underlying conditions such as PPID, insulin resistance or metabolic issues, a history of laminitis, ulcers or chronic digestive problems, leaky gut, hives or chronic skin issues, or any state of immune compromise. These horses often have a harder time processing immune challenges and may be more prone to reactions and flare ups.

It’s also essential to consider whether your horse has ever reacted before. If your horse requires bute or banamine to “get through” vaccines, that is not normal— it is an indicator that you horse is struggling or may be experiencing an adverse reaction. Another question to explore is whether titers are an option. Titers can help determine whether your horse already has immunity, and while they are often more expensive than vaccines, they can be incredibly valuable for horses who are sensitive or have a history of reactions.

Finally, take time to understand what is mandatory versus optional for your horse. Not all vaccines are required, and not all are appropriate for every horse. Your horse’s vaccine plan should reflect their individual needs, not a blanket protocol.

If You Choose to Vaccinate: Support Matters

If vaccination is the right choice for you and your horse, there are ways to reduce the risk of reactions:

1. Avoid combination vaccines when possible. Try to space out their vaccines to reduce immune load. Combination vaccines typically contain more total adjuvant and preservative (aluminum and mercury) load than single‑antigen vaccines, because each antigen in the combo requires stabilization.

2. Avoid giving vaccines at the same time as other procedures.
Stacking multiple stressors on the body at once can overwhelm a horse’s system. I often see vaccines administered during dentals, scopes, sedation, or joint injections, and this combination places a significant burden on the immune system. When the body is already processing sedation, inflammation from dental work, or the immune activation from joint injections, adding a vaccine on top of that increases the likelihood of a reaction. It’s simply too much at once. Spacing out procedures allows the body to recover and respond appropriately, rather than being pushed into overload.

3. Prepare your horse before, during, and after vaccination.

Download my full support guide.

Equine Vaccine Support Guide

4. Learn more about toxic load and immune overwhelm.

You can watch my webinar from the Holistic Equine Vaccine Conference with Dr. Jeff Grognet on Solving the Toxic Overload Problem in Horses—vaccines are one part of that bigger picture.

Watch Webinar

5. Give your horse some time off the week of their vaccine. Your horse likely does not feel well after their vaccines, so don’t ask them to work. Take them for a hand walk to get them moving but keep it low key for at least a few days. 

My Personal Experience: Yolo’s Story

I don’t just see these reactions in my clients’ horses—I’ve lived it myself. A few years ago, my horse Yolo developed gastric ulcers two weeks after receiving a flu/rhino vaccine. Immediately afterward, he became lethargic, mildly colicky, and lost his appetite. Two weeks later, his behaviour shifted dramatically—his nervous system felt wired, he became anxious and unsettled, and then he colicked again, something he had never done before. I decided to scope him, and the ulcers were confirmed. Looking back, it made complete sense. He had been over‑vaccinated his entire life as a show horse imported from Germany, and he arrived to me already stressed, nutritionally depleted, and living right at the edge of what his system could handle. That flu/rhino vaccine was the tipping point that pushed him past his threshold. Most owners would have continued vaccinating him annually without realizing what was happening beneath the surface, and he would have continued to deteriorate. I’m grateful I caught it—and we are still working through this years later. I also want to note that I made this decision based on the fear of being judged by my vets, something I will not do again.

Fortunately, I am not the only one making these correlations. There are vets doing research and really starting to correlate gastric ulcers to vaccination. Dr. Renee Tucker is one of those vets, you can always look up her findings and education around this. 

Common Vaccine Reactions I See in Practice

Keep in mind that reactions don’t always happen immediately. Some appear weeks or even months later.

Common, immediate or short‑term reactions

• Injection site swelling
• Hematomas
• Injection site abscesses
• Fever
• Lethargy
• Loss of appetite
• Laminitis
• Colic
• Pain and stiffness, sometimes so bad they can't reach hay on the ground

Delayed or chronic reactions

• Hives
• Scratches and skin issues
• Hoof abscesses
• Behavioural changes (anxiety, tension, reactivity)
• Neurological signs (stumbling, tripping, balance issues)
• Ulcer development
• Extreme weight loss
• Immune dysregulation
• Worsening of pre‑existing conditions (PPID, IR, allergies, gut issues)

If your horse experiences any of these, it’s important to pause and reassess the risk level of vaccines for your horse. These reactions would be a contraindication for further vaccination and often what I find is once they have started having reactions, they seem to worsen.

Remember to report any vaccine reactions to  your veterinarian and the manufacturer. 

Understanding Immune Load

A major part of this conversation is the immune system itself. Your horse has an immune system—just like you—and it plays a central role in keeping them healthy, resilient, and able to handle everyday exposure to viruses, bacteria, and environmental pathogens. When the immune system is functioning well, it responds appropriately to challenges. But when it becomes overloaded, stressed, or inflamed, it becomes far more vulnerable. This is why some horses tolerate vaccines without issue while others struggle. Multiple vaccines given at once, frequent boosters, or combination vaccines can push horses past their threshold. Combination vaccines in particular contain higher amounts of adjuvants and preservatives, including aluminum and mercury in thimerosal. For sensitive horses, that added load can simply be too much for their system to process.

This is why immune support isn’t seasonal—it’s year‑round work. You build a resilient immune system through:

• Appropriate diet and nutrition
• A forage‑first, whole‑foods‑based diet
• Bioavailable minerals and nutrients
• Forage variety to support a diverse microbiome
• Avoiding high‑sugar hay, processed feeds, excessive protein, poor‑quality multi mineral mixes, sugar, soy, dairy, by-product feeds.
• Managing stress load
• Meeting natural movement needs
• Ensuring social connection and companionship

These foundations matter in keeping our horses healthy. When we understand immune load—and support the body accordingly—we can make more thoughtful decisions about how and when to vaccinate.

Final Thoughts: Vaccinate With Intention

Your horse deserves individualized care, thoughtful decision‑making, and a clear understanding of both risks and benefits. They deserve a plan that supports their whole‑body health, not a routine followed simply because it’s what has always been done. Vaccination is one tool—not the only tool—and it should be used with intention rather than obligation. You never have to make choices from a place of fear, pressure, or judgment. When decisions are made out of fear, they rarely end up being the most appropriate ones. 

What I see so often is that owners feel pushed into certain choices because they worry about being judged or because they’ve been told there is only one “right” way to do things. I want you to know that you are allowed to pause, ask questions, gather facts, and listen to your intuition. I know firsthand what it feels like to make decisions based on fear or external pressure—I’ve done it myself, and I’ve regretted it. Our gut feeling matters, and it’s often the piece we overlook. I am here to support you, no matter what you decide. 

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