Last Updated on February 25, 2022 by Allison Price
What allergies are and how they can affect horses’ bodies
Any horse can experience allergic reactions at any time. A mild case of transient itching is a sign of an allergic reaction. However, more severe reactions can cause serious problems for your horse’s health. The immune, respiratory and integumentary systems are the most affected by allergies. If left untreated, they can have a serious impact on an animal’s performance as well as their well-being. Let’s look at why allergies occur, what they do to your horse’s body and how you can treat them or even avoid them.
Allergies and the Immune System
The immune system, a powerful network of cells and antibodies that recognizes dangerous invaders before they can inflict harm on the host, is able to disarm them. This immune response is vital for survival. It protects against all pathogens, including viruses and bacteria. The immune system isn’t perfect. Sometimes the immune system reacts to something that is generally harmless. This causes an allergic reaction. These reactions can be very dangerous.
Samuel White, PhD is a professor of horse science at Nottingham Trent University in England. He is well-known for his research on the identification and development of allergens in horses. “IgE binds with cells and releases inflammatory chemicals. These molecules are responsible to the common symptoms of allergies such as itching and swelling.
Avoid Triggering Allergens
Horses can become allergic to substances in their environment. Lisa Fultz DVM, MS and Dipl. “Hay naturally contains microscopic fungalspores, as well as bacterial, dust, and other components that horses inhale while they eat.” ACVIM is a Florida-based large animal intern medicine specialist who is interested in respiratory disease. “Barns can also be exposed to noxious gases due to the presence of ammonia in their urine. These substances inhaled can cause an allergic reaction that results in narrowing of the airways, mucous production, and cough.
It is possible to reduce common allergens in the horse’s environment and restore his comfort. Fultz suggests that you can remove horses from their stalls and clean out the aisle. You could also try to get rid of the leaf blower entirely. Avoid storing hay in the same barn with sensitive horses. Hay particles and spores can cause irritation, even when they aren’t visible from the air. While soaking hay can take some time, it is essential to help horses suffering from respiratory allergies.
A bonus benefit to feeding hay at ground level is that horses can spend a portion of their day with their heads down, as nature intended. This encourages natural drainage of allergens, irritants and bacteria from the lungs.
Avoid storing hay in the barn with sensitive horses.Dr. Lisa Fultz
Respiratory Allergies & Asthma
Equine veterinarians often use the phrase “Every cough means one thing”. This could be allergy-induced asthma. Recent research has focused on the causes and effects of what is now known as equine asthma.
White states that horses with severe asthma would have lower levels of inflammation and obstruction. This could manifest as frequent coughing, mucous buildup and exercise intolerance. Milder cases of asthma can still be associated with poor performance, coughing, inflammation, mucous production and mucous production.
Many respiratory allergies are caused by dust in bedding and hay. Veterinarians recommend that horses be exposed to fresh air as much as possible. A small number of horses with asthma are affected by pasture-associated equine asthma. These horses require the opposite treatment. They are more comfortable in a barn that is well ventilated. Although most common in the summertime of the United States, pasture-associated equine asthma has been reported throughout the world.
Skin Allergies
The skin, which is the largest organ in the body, serves as the immune system’s first protective barrier. It is a common place for allergic reactions. The most common manifestation of skin allergies is urticaria (hives). Hives are generally harmless and self-limiting. However, they can be uncomfortable and sometimes lead to angioedema or purpura (blood vessels rupturing internally and leaking blood). Both of these can be extremely serious. Pruritus, or itching due to skin allergies can lead to hair loss and pruritus. These conditions can cause discomfort and lead to skin irritations that can then be worsened by untreated. It is crucial to contact your veterinarian immediately.
Skin reactions can be caused by many allergens. Horses can develop allergies to the saliva of biting insects (e.g. gnats and black flies as well as stable flies and horn flies). This is known as insectbite hypersensitivity (IBH). IBH can be labor-intensive to manage because insects are almost always present in horses’ environments for at least a portion of the year. You can help by providing fly clothing, spraying liberally and avoiding turnout at dawn and dusk, as well as using fans in stalls to stop the flow of insects. Itching can cause severe skin and hair damage, which can take several months to heal.
How to manage and treat allergic reactions
There are many medications that can be used to treat your horse’s allergy. Some of these medications are best used as preventive measures in horses with sensitive skin. You can purchase antihistamines like cetirizine over-the-counter at any pharmacy or drug store, or you may need a prescription from your veterinarian to use hydroxyzine. Your doctor might prescribe corticosteroids like prednisolone or dexamethasone to provide quick and effective relief from immunosuppressive conditions such as allergies.
Although these anti-inflammatory drugs are generally safe for horses, some people may develop the debilitating hoof condition laminitis. Because these conditions can also lead to laminitis, veterinarians should be cautious about administering corticosteroids. Fultz says that veterinarians will use steroids in these cases sparingly and at lower dosages than is recommended. Or they may switch to non-steroidal medication.
Apoquel (oclacitinib), a new prescription drug, has just been released and could prove to be useful for horses with allergies. Fultz states that although the drug is not approved for dogs with allergic dermatitis, initial tests have shown that horses can absorb it well. The drug targets cytokines, which are pro-inflammatory proteins that cause itching and inflammation. This helps to relieve symptoms of skin allergies. The drug does not have any side effects, unlike steroids. Apoquel was chosen over corticosteroids by several of her patients with severe allergies who are also at high risk for developing laminitis. However, she says that not all horses are allergic to corticosteroids and that they are better suited for some cases.
Your veterinarian may recommend that corticosteroids be administered aerosolly through the nose to horses suffering from asthma. This reduces the risk of the medication getting into the bloodstream. A nebulizer, inhaler or single-nostril aerosol chamber can be used. “The anti-inflammatory/immunosuppressive response is … confined almost exclusively to the lungs, avoiding a bodywide effect,” says Fultz.
Immunotherapy
Can you cure allergies? Fultz says that immunotherapy (also known as hyposensitization treatment) is a method to develop allergen-specific immune tolerance.
In a 2019 study Radwanski et al. found a significant improvement in 76% of horses with skin allergies within one year of using allergen-desensitization serums.
White explains that immunotherapy is a method of injecting gradually increasing amounts of an allergen subcutaneously (just below the skin) most commonly. These are called allergy shots. These shots result in the production antibodies that prevent the allergy-causing IgE (allergy-causing IgE) from recognizing the allergen and thus prevent the symptoms.
Fultz says that this process gradually teaches the immune system how to tolerate irritating substances. In the field of immunotherapy, there is always new innovation. White is currently part of a team that studies the possibility of injecting allergy shots under horses’ tongues using a liquid. This could be an alternative that is easier and more affordable for horse owners.
Allergy Testing
Your vet will not administer immunotherapy unless you have identified your horse’s skin and respiratory allergies. Intradermal allergy testing, which involves a dermatologist subcutaneously injecting small amounts of allergens into a cut area of the horse’s neck by a veterinarian, is the best method. If the horse has an allergy to one of the substances, the horse’s immune system will produce a reaction and form a hive at the site. Serum (blood) testing is the second option. Although it is easy to do, Fultz warns that it can not always accurately predict the allergens.
Fultz suggests that Fultz conduct elimination trials if she suspects that a product or ingredient is the cause of an allergic reaction. Eliminate all non-essential supplements and topical treatments from your horse’s daily diet. These include shampoos, shampoos and liniments, as well as fly sprays, conditioners, and other topical solutions. You can then reintroduce each one one at a time while you monitor for allergic reactions or hives. This is an easy, cost-free way to do it yourself.
Flaxseed Nutritional Supplements
flaxseed is a simple, economical and effective ingredient for allergy management. This omega-3-rich, anti-inflammatory, and antioxidative plant is found in many allergy and skin products. Flaxseed has been shown to reduce the appearance of skin lesions in IBH horses by researchers (O’Neill et. al. 2002).
Unique Allergens
Hypothetically, horses can be allergic to any substance he inhales, touches, ingests or has been injected with. White’s research has shown that allergic reactions can be unexpected.
“Recently, we have found that latex, which is everywhere in the horse’s environment–embedded in riding surfaces and racetracks, for example–may be associated with severe equine asthma,” he says. “In fact, our recent analysis of nearly 400 allergens showed that latex proteins were the most important allergens to diagnose severe equine asthma.”
White believes that, while more research is needed in horses, veterinarians should consider the possibility of latex exposure as a risk to horse respiratory health.
Although rare, allergies to vaccines and medications can also occur. Anaphylaxis is a serious allergic reaction that can lead to an immediate, life-threatening, and potentially fatal, blockage of the airways, and a whole-body reaction. These events are almost impossible to predict so it is important to keep track of any previous reactions in your horse and to communicate them with your veterinarian.
Take-Home Message
Prevention is the best option for horse owners with equine allergies. It’s pollen and insect season. Talk to your veterinarian if your horse has seasonal allergies.
