The Latest Understanding, Treatment and Nutritional Intervention For Horses Experiencing Skin & Respiratory Allergies
Much like the impact that allergies have on humans and their daily quality of life, horses are affected by both skin and respiratory allergies that go beyond simple discomfort to limit performance capacity, cause infection, alter behavior and, in severe cases, cause permanent damage to the skin and lungs.
Allergies are a constant frustration shared by horse owners and veterinarians. Their specific cause is often shrouded in mystery, and the breadth and effectiveness of available treatments are limited. There are, however, several insights gleaned from existing data, evolving research and anecdotal success seen by veterinarians that are offering relief to affected horses.
What is an “Allergy?”
“Allergies are immune disorders characterized by hypersensitivity to specific substances that result in an excessive inflammatory response,” explains Tara Hembrooke, PhD, MS, Research Scientist with Platinum Performance, Inc. “Most commonly,” she continues, “allergic reactions affect the skin and respiratory airways in horses and generally develop in response to exposure to insect bites, molds, spores and certain proteins present in pasture grasses.” Allergies are ubiquitous, meaning that potential causes are everywhere in the typical horse’s environment, making allergens difficult to avoid and pinpoint diagnostically.
“The number one thing I try to do is first identify the problem and be as specific as I can,” says Roland Thaler, VMD, owner of Metamora Equine in Metamora, Michigan. “When I get a horse with a cough, runny eyes or increased respiratory effort, then I try to say ‘is this an allergy, a bacterial issue or a virus?’ ” A veterinarian’s primary approach is very often an elimination strategy; slowly eliminating elements from a horse’s environment until symptoms improve and the cause of the allergic response can be determined, or at least narrowed.
The Immune System Component
With an allergic response being attributed to an immune system hypersensitivity, maintaining a healthy immune system becomes greatly important. “In addition to a balanced diet, supplementation with specific nutrients can help support the immune system and, thereby, reduce the occurrence of allergic response and other immune-related reactions,” says Dr. Hembrooke. The health of the equine immune system plays a role in virtually every other aspect of a horse’s overall health and, arguably, their performance as well. One of the most effective ways to maintain an optimally-functioning immune system is to provide the foundational support needed for optimal wellness; it’s one of the primary reasons Platinum Performance® was developed in clinical practice over 20 years ago. Paying close attention to a horse’s diet, then supplementing them with the missing pieces and more therapeutic nutrients lays the groundwork for horses to thrive long-term as healthier animals and more durable athletes.
Skin Allergies & Insect Bite Hypersensitivity
Skin allergies are by far the most common type of allergies in horses, developing as a result of exposure to virtually anything the horse may come into contact with, from pollen, dust and mold to shampoos, fly spray and saddle pads. Although rare, skin allergies can also present as a reaction to certain grasses, grains, feed additives and supplements, and take on several forms. “Skin allergies may present as itchiness and possibly damage to skin like bald spots or scabs,” says Dr. Hembrooke. The intersection of the immune and nervous systems results in an itching sensation for affected horses, oftentimes resulting in loss of use until the allergic response can be mitigated. “Raised bumps that may or may not be itchy may be another sign,” continues Dr. Hembrooke, “and while skin allergies are mostly seen as a nuisance, they can result in infection if not controlled properly.” Kim Gill-Favier, DVM, shares the frustration of chronic skin allergies, “The most common thing I see is urticaria, or hives. It always seems to come up in February and March when we’ve had a lot of rain, things are starting to bloom and there may be molds. Horses will start to have urticaria, which you treat once and it always seems to come back.”
Horse owners don’t necessarily equate a horse’s insect bites and the subsequent reaction to an allergic response, but in reality, horses can be predisposed to react more severely depending on the state of their immune system. Insect bite hypersensitivity (IBH) is the most prolific equine allergy, and subsequently, among the most extensively studied. Characterized by a skin reaction to bites from insects such as Culicoides, flies, mosquitos and other insects, IBH affects an incredibly large number of horses regardless of breed, age or discipline. “IBH is really a big problem,” says Dr. Thaler. “I don’t think we approach it strongly enough and fly spray just isn’t cutting it. We should be treating these horses proactively.” Aside from removing horses from an outside environment during times of prime insect activity, such as dawn and dusk, fans can be added to barns and stalls to help curb insect activity. Working from within the horse, their diet should be focused on reducing inflammation and maintaining a balanced immune system. High-quality forage with limited grains and
concentrates plus a focus on omega-3 oils and supplemented omega-3 fatty acids and antioxidants can lay the groundwork for a horse that’s more equipped to handle the insult of insect bites.
The study of respiratory allergies in horses is advancing well beyond the limited understanding of decades past. A greater link between the horse’s environment and varying levels of respiratory distress has been made, leading to a change in nomenclature and stronger ties between the study of respiratory allergies in horses and humans. “We study what is now called equine asthma,” explains Cyprianna Swiderski, DVM, PhD, DACVIM, Associate Professor, Equine Medicine Department of Clinical Sciences at Mississippi State University. “And the first thing is to recognize that equine asthma is a syndrome that typically houses what was formerly known as inflammatory airway disease and also RAO, or recurrent airway obstruction.” There are two levels of severity when it comes to equine asthma, with the first being formerly known as equine inflammatory airway disease, and now referred to as mild to moderate asthma. The second was formerly regarded as RAO, and now deemed severe asthma. “With severe asthma, there are horses who go in the barn, they’re exposed to moldy hay, and that’s how they trigger that disease,” says Dr. Swiderski. Growing up in Maryland, Dr. Swiderski was shocked by the prevalence of severe asthma in the horses she saw when she moved to the southeastern United States. “These horses differed from the barn-associated disease I had grown up with, in that they experienced signs on pasture during conditions of high heat and humidity. I had never seen horses in so much distress,” she says, with a hint of sadness underlying the determination in her voice. “I’ve become passionate about equine asthma because my heart goes out to these horses that have no real way to escape from the pasture associated antigens that are triggering this disease that is chronic and progressive. Horses ultimately can die from it.”
Symptoms of the barn associated form of severe equine asthma can include nasal or ocular discharge, coughing or labored breathing and can often be greatly impacted by modest changes to a horse’s environment. “I’ll first try to get this horse away from the dust,” says Dr. Thaler. “I’ll try to get [the barn associated horses] outside the barn, have their hay soaked to minimize what they’re inhaling from it, and I’ll have my clients add the right oil to the feed.” Choosing an oil, such as omega-3-rich flax oil, can reduce the severity of the inflammatory response, while more pro-inflammatory omega-6-heavy oils, such as corn oil, can further exacerbate the problem. Beyond oils, short-term treatment with corticosteroids is commonplace to help get symptoms under control, as is the use of certain targeted nutrients for longer-term benefit. “My reason for going to nutrition is to get these horses off the corticosteroids as quickly as I can while using as little of them as I can,” says Dr. Thaler. “A lot of my show horses are pretty overweight, so for several reasons I try to use nutrition, and specifically, the Platinum Skin & Allergy formula. I use it as an adjunct to therapy and to support these horses by trying to reduce the inflammatory response.”
The Impact of Your Horse’s Diet
Inflammation is known to play a significant role in allergic response. Horses maintaining a low level of chronic inflammation are more equipped to handle allergens while horses above the inflammatory disease threshold with unchecked chronic inflammation are more apt to experience a serious reaction in response to an allergen. Diet is perhaps one of the best ways to influence health and help manage inflammation in a horse’s body.
“A primary goal is to establish or re-establish a proper balance between the high-inflammatory omega-6 fatty acids and the low-inflammatory omega-3 fatty acids,” says Dr. Hembrooke. Oils high in omega-6 fatty acids, like corn and cottonseed, should be eliminated and replaced with low-inflammatory oils high in omega-3 fatty acids like flaxseed. Antioxidants like vitamins E and C may help with repair of damaged tissue. Also, these antioxidants can help with the internal inflammatory state. Oxidation and inflammation are intertwined. If there is a strong immune response, then there is going to be an increased production of free radical species that can be mediated with antioxidants. Quercetin is a powerful polyphenolic antioxidant that offers further support for allergies by naturally inhibiting the release of histamine. Pro- and prebiotics should also be considered as they will
“I remind my clients how much it costs to have me come out to treat their horse for hives compared to how much it costs to practice proactive care and use the Platinum formulas I recommend.”
Kim Gill-Favier, DVM
support a healthy gut microbial population that is going to then support a healthy immune state.
Starting with the right hay is crucial, but realizing exactly what nutrients hay is providing — and what it’s not — is equally as important. For instance, the level of omega-3 fatty acids and antioxidants in fresh, still growing alfalfa can be 38-40 percent higher than the same alfalfa just 6 weeks post-harvest. With nutrient rates diminishing over time in even the highest-quality hay, baled hay stops short of delivering all of the necessary nutrients horses need to function at their best, making supplementation an excellent choice. It’s for this reason that foundational wellness and performance formulas like Platinum Performance® Equine, Platinum Performance® CJ and Platinum Performance® GI are recommended to support immune function, allergic response and total body health. “Most of my patients are already on Platinum Performance Equine or Platinum Performance CJ,” says Dr. Gill-Favier of her approach. “If they have recurrent urticaria, then I put them on the Platinum Skin & Allergy. I warn my clients that it may take a few weeks to turn their horses around, but it seems to solve the problem. I really don’t have many allergy-related issues anymore with this program, and horses with fly bites respond really well to it also.”
When ‘Natural’ May Be Better
Targeted nutrition can be significantly effective in supporting a normal allergic response because of its impact on inflammation, managing oxidative stress and helping to maintain an optimal equine immune system. Though natural, these nutrients are potent and well-researched tools for veterinarians and horse owners to turn to for longterm results in horses with chronic allergies. “For me, I would rather take a nutritional approach or an herbal approach,” says Dr. Gill-Favier. “I don’t want to have horses on (dexamethasone) all the time; I think it’s dangerous, and especially so with a lot of these horses that are borderline metabolic.” Therapeutic nutrients can be used as an adjunct to clinical therapies for sustained results, helping a horse’s body to heal without the side-effects often seen with prolonged pharmaceutical intervention.
Prevention vs. Treatment
With the use of environmental intervention and nutrition, a large majority of allergy issues can be avoided before they ever have the opportunity to become clinical. “There’s no one thing,” says Dr. Gill-Favier. “You have to manage the environment, nutrition and take a total holistic approach.” From keeping dust under control to managing insect activity and choosing a high-quality, anti-inflammatory diet together with the right supplements, small steps can lead to significant results. “I remind my clients how much it costs to have me come out to treat their horse for hives compared to how much it costs to practice proactive care and use the Platinum formulas I recommend,” says Dr. Gill-Favier.
“With additional research into understanding the complex immune mechanisms associated with allergic responses in horses, it will be possible to gain a better understanding of how to manage the clinical manifestations of allergies,” says Meri Stratton-Phelps, DVM, MPVM, DACVIM, (LAIM), DACVN, Veterinary Clinical Nutritionist with Platinum Performance, Inc. “The effect of the gastrointestinal microbiome on the health of the immune system and an improved understanding about the barrier function of equine skin as it relates to atopic dermatitis are important areas of research in the future.” The gut microbiome to which Dr. Stratton-Phelps is referring is seen by many in both veterinary and human medicine to be the so-called ‘next frontier.’ With far-reaching influence on numerous systems in the body, the gut microbiome is thought to affect immune function, metabolic health, allergic response and even play a role in predetermining a human or horse’s propensity for disease.
While other aspects of veterinary medicine may be more clearly defined and their treatments more black and white, equine allergies are a gray area that take trial and error combined with tried and true strategies for the most positive outcomes. Much is happening and great hope is on the horizon for significant breakthroughs that could further improve the health, longevity and performance capacity for horses afflicted with skin and respiratory allergies. “In our horses where this is chronic and progressive, if we can decrease their progression, then they can stay where they are longer, and if we can moderate them, then they can have a longer and better quality of life,” says Dr. Swiderski.
Ultimately, it comes down to a greater focus on prevention and a treatment plan with long-term and sustained results as the end goal. Dr. Gill-Favier reminds herself often of why she chooses the approach she does. “The body — whether that’s a human or a horse — has a tremendous capacity to heal if we give it the right tools and get out of the way.”
For Supportive Literature:
• Fadok, Valerie A. Update on Equine Allergies. Vet Clin Equine 29 (2013) 541-550.
• Jensen-Jarolim et al. Outstanding animal studies in allergy II. From atopic barrier and microbiome to allergen-specific immunotherapy. Curr Opin Allergy Clin Immunol 17 (2017) 180-187.