If your horse is rubbing its mane, swishing its tail excessively, or breaking out in hives, you’re not alone—and it may not just be bugs or behavior. Allergies in horses are more common than you might think, and they can affect both the skin and respiratory systems.
In this episode of Your Vet Wants You To Know, board-certified veterinary dermatologists Dr. Brittany Lancellotti welcomes follow dermatologist and horse lover, Dr. Julia Miller, who uncovers the often-overlooked world of allergies in horses. From chronic hives and hay sensitivities to the connection between equine asthma and environmental allergens, this episode is packed with practical advice for every horse owner.
What Do Allergies in Horses Look Like?
Allergic reactions in horses aren’t always obvious. According to Dr. Miller, the signs can vary depending on whether the skin or respiratory tract is affected.
Common Skin-Related Signs:
- Hives (urticaria)
- Itching and rubbing
- Hair loss or crusty patches
- Seasonal flare-ups
Respiratory Signs of Equine Allergies:
- Coughing or nasal discharge
- Exercise intolerance or poor performance
- Flared nostrils or increased respiratory effort
- Diagnosed equine asthma (formerly known as heaves or IAD)
Pro tip: Respiratory allergies in horses are often connected to the same environmental triggers that cause skin allergies!
What Causes Allergies in Horses?
The most common triggers for allergies in horses are environmental allergens. Horses, just like people and dogs, can become hypersensitive to substances in their everyday environment.
Common Equine Allergens:
- Hay and hay dust
- Dust mites
- Weed and tree pollens
- Mold spores
- Insect bites (especially Culicoides, or “no-see-ums”)
- Dander from barn cats or other animals
Fun fact: Dr. Miller’s own horse broke out in hives due to allergies—and the journey led her to become an equine dermatology expert!
How Are Horse Allergies Diagnosed?
The gold standard for diagnosing allergies in horses is intradermal allergy testing. This procedure is performed by a veterinary dermatologist and involves injecting small amounts of allergens into the skin to observe the horse’s reaction.
Intradermal testing helps identify:
- Specific environmental triggers
- Candidates for allergen-specific immunotherapy (custom allergy shots or oral drops)
Visual tip: Keep scrolling to see photos of intradermal skin testing on horses below!
What Treatments Are Available for Allergies in Horses?
Managing allergies in horses usually involves a multimodal approach—especially since long-term steroid use can be risky.
Multimodal Treatment Options Include:
- Allergen-specific immunotherapy (ASIT)
- Antihistamines like cetirizine or hydroxyzine
- Omega-3 fatty acid supplements (for skin barrier support)
- Chlorhexidine or lime sulfur topicals
- Steroids (short-term relief during flares)
- Environmental management (dust-free hay, improved airflow)
Dr. Miller emphasizes tailoring treatment to each individual horse—especially when dealing with both skin and respiratory symptoms.
Key Takeaways: What Every Owner Should Know About Allergies in Horses
- Allergies in horses often show up as hives or respiratory distress.
- Environmental triggers—like hay, dust, and pollen—are common culprits.
- Intradermal skin testing is a powerful diagnostic tool for allergies in horses.
- Multimodal treatment leads to better long-term results and fewer side effects.
- A board-certified veterinary dermatologist can help create a personalized plan.
Full Transcript for Allergies in Horses
Dr. Lancellotti: Welcome, everyone, to today’s episode of Your Vet Wants You To Know. I am excited to talk about a different species, when it comes to allergies. We talk a lot about allergies in dogs and cats, but we don’t talk a lot about other how allergies present with other species. So today, I’ve brought on a fellow dermatologist, Dr. Julia Miller, to talk all about allergies in horses. Welcome, Dr. Miller.
Dr. Miller: Hi. It’s so good to be here. Thank you.
Dr. Lancellotti: Tell us a little bit about your background. How did you get interested in dermatology, and in horses, specifically?
Dr. Miller: So I’ve been a horse girl since I was four years old. That’s when I got my first pony, Maggie. She was a real delight. I loved her. I rode my whole life. And when I ended up going to vet school, I was pretty certain that I wanted to be an equine podiatrist, because I took a gap year between undergrad and vet school, where I became a certified farrier. I loved horses and horse hooves. In vet school, I did equine track at Cornell, doing all of the extracurricular horse things. Externships in Lexington- all of that. But at Cornell, they don’t track too much, so I still had to take quite a few small animal cases and courses, and I think that really helped me, in the end. As it turns out, I am definitely one of the poster children for, “you never know where you’re going to end up in veterinary medicine, so enjoy the ride as much as you can.” Right?
Dr. Lancellotti: Yeah. We’ve heard that a lot from some of our guests. They’ve gone down these paths where they expect one thing, and all of a sudden, they’ve wound up in a completely different aspect of veterinary medicine. So it’s really cool to see how many different avenues there are.
Welcome to Dr. Julia Miller
Dr. Lancellotti: So how about dermatology? You are a board certified veterinary dermatology specialist. How did that come about?
Dr. Miller: After vet school, I did a large animal rotating internship at University of Georgia, and I loved it. But to be perfectly honest, I was just kind of burned out, after my internship, from specialty care. I just wanted to go and practice. That’s what I wanted to do. Interestingly, my life is a series of comedic errors, at times. At the time when I left my internship, it was 2013, and the economy was not very good, so equine veterinarian jobs were not very prevalent. I actually ended up taking a mixed animal job because that was more available, and more fiscally responsible, truthfully. That’s when I found myself really loving my small animal cases, more and more, every day. I still loved working with horses, but I started to embrace the dark side, if you will, and enjoy my small animal cases a lot. Then, as much as I didn’t want to love dermatology (because spoiler alert, my dad is a veterinary dermatologist, so this apple really tried hard to fall far from the tree- I was doing my best), but when I was in general practice, I just found myself loving my derm cases. I’m a talker, I’m a people person, and I love the relationships that you build with your derm cases. I love the funkiness of a derm case, the arts and crafts of it all- I really enjoy that. I found myself becoming more and more interested in dermatology as I moved through a few different mixed animal practices. Then, I finally gave in and called my dad, one day, and I said, “Dad, I’ve got to tell you, I think I want to do dermatology.” I think he hooped and hollered in the background, because I finally admitted something that had been brewing for a while, to be honest with you. So I returned to Cornell and I did my derm residency there. Then, after my residency, I stayed on there as faculty, for a while, and now I’m back out in horse country, in Kentucky, as a dermatologist in private practice.
Dr. Lancellotti: That’s great. That’s really fun. I bet he must have been over the moon excited about your decision to follow in his footsteps. That’s great.
Dr. Miller: He’s not a very emotive man, in general, but I think he was.
Dr. Lancellotti: I mean, hooping and hollering- that’s pretty emotive.
Dr. Miller: Pretty good. Yeah.
Allergies in an Arabian Horse
Dr. Lancellotti: So I am excited to talk about horses, today, because this is something that I don’t get to see, on a very regular basis. But I did enjoy some of the horse cases that I saw during my residency, working up their allergies. When you think about horses and allergies and the cases that you’ve worked with, is there one horse, in particular, that comes to your mind, that you have fond memories about, or maybe memories of struggling with that case? Tell me a little bit about one horse that sticks out.
Dr. Miller: Yeah. There have been some real gems that I’ve really enjoyed, but probably one that sticks out to me the most was an older Arabian horse that I loved dearly. And I loved his client. This is when I was at Cornell, and they drove from Connecticut, so it was quite a trek to come see us. This horse actually had some skin issues, as well as respiratory issues. It had been diagnosed with equine asthma, and this family had actually previously lost their other horse because of equine asthma, and having to use so many steroids that the horse ended up foundering. Unfortunately, it had to be euthanized, so the owner’s experience was very fearful of medications.
They loved this horse with everything, and they really wanted to take care of this horse as much as they could, so they were seeking alternate treatment options for allergies and equine asthma. So this particular horse came to Cornell, we did some intradermal skin testing (which is one of my favorite things to do), and we put the horse on immunotherapy. Then, that client and I talked quite a bit about managing the environment, about what we could do for its airway, and also what we could do for its skin. We were in touch quite a bit, and the horse ended up doing incredibly well, managed on only immunotherapy, which is so safe. The client was just so thankful. We would have regular catchups. “How are you doing now? Now that it’s springing, how’s everything going?” And the horse did really well, so that was a very notable one for me.
Allergies in Horses: An Overview
Dr. Lancellotti: So let’s talk a little bit about allergies in horses, specifically. We’ve talked a lot about allergies in other episodes, but it’s always been in relation to dogs and cats. The way the allergies affect dogs and cats is a little bit different from how it can affect horses. What are some of the things that a horse owner might notice, if their horse does have allergies?
Dr. Miller: That’s an excellent point to bring up- horses are not big dogs. They’re kind of big cats, in some ways, in some of the things they do. but they do have different signs for their allergies. One of the most notable ones is that horses love to make hives. That’s something that we don’t see in our cat species, but we really don’t see that commonly in dogs either. But man- does a horse love to make a hive.
I want to remind everybody that horse hives come in all shapes and sizes. They can just be a little bump. They can look like a doughnut of swelling. They can have what’s called zebra urticaria, where it almost looks like there’s waves in their skin. Horse hives can have unique clinical experiences, and that’s one of the big things we see with horses that have environmental allergies, for sure.
The other thing is that horses are not going to look traditionally itchy, like your dog. That doesn’t mean that they aren’t itchy, but they show their itch in different ways. One of the ways they might show their itch is by rubbing their mane off. Some people think that if a horse has rubbed their mane off, it’s just a stall vice. But in reality, that horse is probably itchy, and that’s why they’re actually rubbing their mane, which can be the same thing with the tail.
When you go out in the pasture and you see the horses who have their tails bushed out, because they’ve been scratching their tail, that can also be a sign of environmental allergies. They’re not necessarily going to chew on their feet like a dog does, but they might rub on the barn. I actually saw a horse that, very cleverly, was rubbing its belly on the ground. They do itch like our small animal species, but they demonstrate it in different ways, so you have to be a little clever, in noticing their clinical signs of allergy.
Dr. Lancellotti: It sounds similar to how a lot of people will assume that a cat is anxious, or has some type of behavioral issue, if they’re over grooming their belly, but it’s actually itchy from allergies. With a horse, they’re taking off the hair on their mane and their tail because they’re itchy, not because they’re anxious.
Asthma (Heaves, RAO, COPD) with Allergies in Horses
Dr. Lancellotti: In the story, at the beginning, you mentioned a horse that had both skin problems and respiratory problems. Is that something that you see commonly, or is this like a one-off case?
Dr. Miller: I am getting more and more consultations for horses with equine asthma. We used to call it heaves. That was a big one- recurrent airway obstruction (RAO). Then it was chronic obstructive pulmonary disorder (COPD). Now, everyone is really seeing it as more of an allergic aspect. When you start calling it equine asthma, that’s when the allergist and the dermatologist start to get involved with things. I have actually had several very successful cases now that have come to me for allergy testing and immunotherapy, to help manage their respiratory disease. I don’t guarantee success, but I’ve had quite a few cases that have done really well with the introduction of immunotherapy. You get the skin stuff, the recurrent hives, itchiness, and things like that, and then also, on the other side, there can be a respiratory component, in some of these horses.
Triggers of Allergies in Horses
Dr. Lancellotti: We talk about fleas, food and environmental factors, in dogs and cats. In terms of horses, what are the most common things for horses to be allergic to? And my husband wanted me to specifically ask you if horses can be allergic to hay.
Food Allergies in Horses
Dr. Miller: Horses probably can have food allergies (in the traditional sense that we think about with dogs and cats), but to pull everything back and find out what the horse is allergic to, in an elimination diet trial, is incredibly difficult, in the equine world. You need to change the hays. And how do you find a pure hay that is just Timothy or just alfalfa? You need to change the grains. Horse grains are a mixture of about 90 billion things. Do you stop the grain? Do you not? Diet trials and horses are practically just very difficult, so it’s possible we might be under diagnosing true food allergies in horses, but I don’t know that we’re necessarily going to get that data anytime soon, just because of the practicality.
Environmental Allergies in Horses
Dr. Miller: For the vast majority of horses, I think they are much more allergic to environmental things. And those allergies come from both inhalant and contact. Hay is one of the number one things we see- Hays and grasses. So that could be Timothy hay, alfalfa hay, coastal, or any particular type of hay they’re on. But I get a lot of horses that are also allergic to weeds and there are weeds in the horses world everywhere. I get horses that are allergic to dust mites, which is great fun if you’ve ever been in a barn that isn’t dusty, I’d love to visit. They can also be allergic to things like humans or the barn cat. I have also had a few horses that were incredibly reactive to cat, and then lo and behold, there’s a couple of barn cats hanging around. So they can be allergic to many of the same things as dogs and cats. But I certainly do see a lot of grass, weeds, and hay.
Identifying Triggers of Allergies in Horses
Dr. Lancellotti: If we are going to figure out the trigger, how do you go about doing that? Are there certain tests that you recommend ?
Allergy Testing in Horses
Dr. Miller: In order to find out what they’re allergic to, and start that process, my most favorite thing is allergy testing. They’re my favorite species to do it in. They respond and react beautifully. The test is very safe to do, in a horse. So that is 100% my favorite thing to do, to figure out what’s going on with their allergies.
Dr. Lancellotti: Yeah, I love doing allergy testing and immunotherapy, in our small animal species, as well. And I remember, from my residency, going out and doing those tests on the horses and seeing what beautiful hives that they have on their skin tests. It’s so easy to read and so distinct, especially compared to cats, who make really terrible skin tests. They’re just not great to skin test at all. Even when they get a good skin test on a dog, it’s nothing like a good skin test on a horse, so that must be a lot of fun.
Dr. Miller: A horse skin test is going to show you, with your eyeballs, so much better than small animal. I agree with you wholeheartedly. You get these very flat nothings, and then these big juicy hives. They’re my favorite. I love them.
Treatments for Allergies in Horses: Steroids
Dr. Lancellotti: Once you’ve identified their trigger, and you’re trying to get them relief, what different options do we have for horses? It’s certainly a little bit different than what we have available for our small animal patients. What kind of medications might you recommend? Are there different environmental changes that the owner could make? You mentioned changing out the bale of hay, if there’s an acute reaction, but what kind of things can the horse owners do to make their animals’ life a little bit easier?
Treatments for Allergies in Horses: Antihistamines
Dr. Miller: Antihistamines are another potential option, for horses, with variable success. Some horses seem to respond fairly well to antihistamines, and in other horses, it doesn’t do anything for them. I think it’s always worth a try, because what if you have the horse that does well? Especially, in the more mildly affected horses. If you have a horse that’s just incredibly itchy and hivy, an antihistamine is probably not going to cut the mustard and do quite enough. But there’s a number of different antihistamines out there, that I will use over the counter- Zyrtec (cetirizine), hydroxyzine, or tri-hist granules, so you can certainly speak with your veterinarian about what options they may offer for antihistamines, as well.
Treatment of Allergies in Horses: Supplements
Dr. Miller: Another thing that I like, in managing anything with environmental allergies, is multimodal management. There’s not one silver bullet. We do lots of different things to help those horses out. Some of the things I actually really like are some very nice anti-itch or pro skin supplements on the market. I feel like a supplement seller right now. Welcome to Horse World. But there are some lovely ones. Platinum Performance makes one called Skin and Itch. Smart Pack has some nice ones too. They tend to be higher in omegas, and horses benefit from Omega supplementation, much like our dogs and cats do, as well. Some of them have different herbal formulations. And the supplements are not going to be the answer to a severely affected horse, but as part of multimodal therapy, I have seen some excellent success, because they help promote the epidermal barrier and they also help reduce some of the inflammation there.
Avoidance of Environmental Triggers in Horses with Allergies
Dr. Miller: Environmental changes are really hard. Certainly, changing hay source is something I recommend routinely. Sometimes, changing pastures has helped some of my horses, although that’s a little up in the air. But I’ve had a few of my clients actually move barns, and that has helped their particular horse. In desperate times, that might be something to consider.
But much like you mentioned before, avoidance of things that they’re allergic to in the environment is practically impossible. There’s no way to remove every dust mite from a barn. I don’t recommend anybody to get rid of their barn cats because barn cat dander is going to be there for the next 30 years, even if there isn’t a cat. So keep your cats please. We love them. They’re wonderful. One of my favorite creatures is a barn cat. Unfortunately, there’s just not a whole lot we can do for avoidance, and that’s where the allergy testing and immunotherapy comes in.
Topical Therapy for Allergies in Horses
Dr. Lancellotti: So what are the other things that we can do which make us less reliant on using medications that have more risks associated with them, especially on a long-term basis? In dogs and cats, we talk about this being a lifelong disease, and it’s a lifelong disease for our horses, as well. So if a horse has foundered once, you want to try and minimize how many steroids they get, so that you can protect them from foundering again and creating those severe problems. I love using multiple things to help manage the disease overall. I think it’s great to use some nutrition.
We do a lot of topical therapies in our dog patients, because they get a significant amount of skin infections, secondary to their allergies. Do you see a lot of those secondary skin infections in horses, the way that we do in dogs? And is there any benefit to doing topical therapy with these guys?
Dr. Miller: Yeah, that’s a great question. I don’t see as much staph or skin infection in horses, which is good, but it is out there. One of the most common times you actually might see a bacterial infection, in a horse, is if that horse was covered in hives. Sometimes, the hives will ooze, and then that ooziness predisposes the horse to getting a bacterial infection. A classic scenario is, “Hey, my horse had some hives the other day. We treated them, but now he’s really crusty. What’s going on?” That often indicates that they may have a secondary staph infection.
Horses respond beautifully to topicals. The good news is that most of us are fairly able to bathe our horses. Maybe not in winter time (things get a little tricky when it’s cold), but certainly in the summer. Most of my horse clients are very used to bathing horses and there are great medicated shampoos out there. Many of the products, like the Dechra products, even have a horse on the label. And horses benefit from the chlorhexidine and miconazole containing products, just like a dog or a cat would, as well. If you can bathe the cat though, good on you. I’m very proud of you.
Shampoos can be very beneficial. There are a lot of excellent topical sprays out there, so I recommend a lot of Vetericyn. It’s a hypochlorous acid (bleach) based spray, but it’s in low concentration, so it works beautifully and is not harmful to the skin. Then there are also even drying powders, if you’ve got a big quarter horse in the back that gets thick thighs. So there are a lot of really good topicals out there, if there are secondary bacterial infections.
One myth I want to dispell is that everybody thinks that if horses get funky skin, that it’s ringworm. I cannot tell you how many times that I’ve heard, “it’s just fungus.” It’s actually quite uncommon that the horse has ringworm or true fungus in the skin. It’s much more likely that the horse has a bacterial infection, so if you’re going to choose a topical product to treat funky crusty skin, choose a product that’s going to cover a bacterial infection, because it’s more likely that it would be effective in that particular horse.
Allergies in Horses: The Big Takeaways
Dr. Lancellotti: It sounds like there are a lot of different options for horse owners that have a horse that’s either developed hives or has had some respiratory issues. If you are a horse owner out there that has a horse that you’re concerned about, don’t be afraid to reach out to your family veterinarian to talk to them about what might be going on. Also, consider finding a dermatologist in your area. We are the allergy specialists of the veterinary world. What are some of the big takeaways that you would like the horse owners listening to remember about equine allergies?
Dr. Miller: Equine allergies are fairly common, truthfully, and they’re in varying degrees. Much like with dogs and cats, they can be mildly affected or very severely affected. Pay attention. If you have that horse that’s buzzing their mane off every summer, there’s probably a reason why that’s happening, and maybe considering a further workup would be a good idea. I think it’s really important that you have a good working relationship with your family veterinarian, so that we’re not just calling them out, in an emergency, when there are tons of hives. Keep on track of things. Call them up and say, “Hey, things aren’t bad. I don’t need you to come out, but what should I do for my horse at this particular point?” If you can head things off at the pass, before needing steroids when they get to full blown hives, I think that’s ideal for a lot of horses.
Pay attention to the little things and then see if you can get on top of management early. Catching things early and often is very helpful. I love topicals, so getting yourself a good medicated shampoo for your horse is always a good idea, but make sure you dry your horses thoroughly, particularly their distal limbs. You don’t want to let the water pool on their legs or they might get scratches. And I absolutely think if you have any concerns or questions about your allergies, in your horse, and you’d like to seek specialist care, we are out there. Dermatologists love to see horses, so reach out and see if getting a barn visit would be an option, because we’d love to help you out.
Veterinarians Who Treat Allergies in Horses
Dr. Lancellotti: Many family veterinarians are comfortable managing horses with allergies, but if we have listeners who are interested in finding a dermatologist near them, there is a link on the website, if you’d like to consult with the specialist. There’s also a link to the American Association of Equine Practitioners, so that you can find a veterinarian who’s specific with horses. There’s also a link for the American College of Veterinary Dermatologists. Dr. Miller, if folks would like to consult with you locally, where could they find you?
Dr. Miller: I practice at the Animal Dermatology Clinic in Louisville, Kentucky. Feel free to give us a call there. Your family vet can also call for consultations. I am happy to chat with your family vet about your case, if you’re too far away, or if I wouldn’t be able to come out and see them. I love to consult with veterinarians on cases. I also practice at a satellite in Lexington, so that also helps me out, some days, when I can get down there. But I would be happy to chat with you or your family vet.
Dr. Lancellotti: I’m sure you get plenty of cases in Lexington with the equine allergies and stuff. There’s a big horse country there. Dr. Miller, you do a lot of stuff on social media, as well. Where can people follow you, if they want more information, to check out what you’re doing in the veterinary dermatology world?
Dr. Miller: Yeah, I’d love to have you guys follow me on Instagram @drjanimaldermatologist. I try to post some small animal and large animal stuff on there. I certainly try to lecture in different places around the country. I’ve done some webinars, so if you see anything, I’d love to have you take a listen. There is a lot of really lovely education out there, this podcast included. I think it’s wonderful that you’re listening. Keep opening your mind and expanding it, and gaining that extra knowledge. I think that one of the great things that social media has done for us is opened up all of these doors, where you can learn a lot from really cool people. So I appreciate you for listening to this podcast, and you, Brittany, for putting it on. It’s really so helpful to get the insider views.
Scratching the Itch
Dr. Lancellotti: In each episode, we end with a segment called Scratching the Itch. This is a segment designed to highlight something, whether it’s a human interest story, a product, or a website. It’s just something that provides relief or makes you feel good, hence, scratching the itch. Dr. Miller, do you have a ‘scratching the itch’ for our listeners today?
Dr. Miller: I do. There is a medication on the market that I adore, which smells really bad, called lime sulfur dip. I’m going to throw this out here because we are in a large animal episode. Luckily, most horses live in barns, so if they smell a little bad, the scent dissipates and we’re okay. If you have a horse that has crusties or itchies, and you’re looking for a product that’s easy to apply, lime sulfur dip is often very effective, and something that I recommend routinely. The benefits are that it’s antibacterial, antifungal, it helps with crusting, and it actually has some anti-inflammatory and anti-itch benefits. And let’s add another one- it helps treat external parasites, as well. So it’s not necessarily a webpage, but there are a number of different lime sulfur containing products out there. Wear gloves when you use it, or else your hands are going to smell terrible for a while, but diluted lime sulfur is an excellent option, if you’re looking for kind of a catch-all treatment that works for a lot of equine skin disease.
Dr. Lancellotti: That’s great. That is one of the most interesting ‘scratching the itches’ that I’ve had. It’s funny because in my mind, as a small animal dermatologist, I would never put lime sulfur as my scratching the itch. I apologize to owners when I prescribe it to them. I’m like, “I’m so sorry. I’m not prescribing this because I hate you. I’m prescribing this because it’s really effective, but it smells really bad.” I just think that’s adorable that’s the something that you highlighted to provide relief or make you feel good, but with that very big asterisk there. It smells awful.
Dr. Miller: So bad. But listen- we’ve all smelled bad things. It’s a temporary scent. And it’s the smell of relief. I think that’s what you need to go for. It’s just the smell of relief and we love it.
Dr. Lancellotti: That’s great. Thank you very much, Dr. Miller, and thank you for your time coming on and talking about this topic today. I hope that there are some listeners out there who have gotten some good information, and feel more comfortable talking with their family veterinarian or reaching out to a dermatologist about their horse’s allergies. Thank you so much for your time.
Dr. Miller: Thank you so much for having me. I really appreciate it.
Dr. Lancellotti: And for everyone out there, I look forward to your next visit with Your Vet Wants You To Know.
