EquiSearch's Ask the Vet: Horse Allergies

Horses with allergies need help regulating their immune systems. Dr. Joyce Harman explains what to do in EquiSearch.com's Ask the Vet.
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Question:My 9-year-old Quarter Horse gelding has many allergies (food/environment). He is allergic to molasses, corn, oats and timothy/orchard mix hay. I changed his diet to a brome hay and Triple Crown Low Starch. He's doing great on his new diet. He is also allergic to some weeds, fungi, some trees and black flies. He will be on a supplement for the flies and a natural fly spray. My vet said it's not his immune system because he is in great health and doesn't get sick, and a friend told me he could have an overactive immune system, and someone else told me he could have a liver problem. Are there any tests a vet can do to check the liver and immune system? What can I do to make him more comfortable in the spring and summer months with his allergies?

Answer: Allergies are actually an over-reactive immune system. Here is a direct quote from Medline, an excellent medical data base for doing research to understand the science behind diseases: "Allergy is caused by an oversensitive immune system, which leads to a misdirected immune response. The immune system normally protects the body against harmful substances, such as bacteria and viruses. It reacts to substances (allergens) that are generally harmless and in most people do not cause a problem."

If your horse has a healthy immune system, as do many horses, he will breathe the air full of pollens, eat any food he wants and will not have health issues. In your horse's case, these common ingredients cause his immune system to overreact and produce symptoms. One fact we need to pay attention to is that no matter how OK your horse may look, any symptom other than perfect health and a deep rich coat color means he is not actually healthy. We have a tendency to think an animal is in good health if he only takes a couple of medications or needs only a few supplements to keep him going. Things like dry, brittle feet, a slight cough only when first starting out, runny eyes and similar mild symptoms are all signs of an imperfect immune system (see a more detailed article on my website).

So the key to helping all horses with allergies (you do not say what symptoms he has) is to help regulate the immune system--not to stimulate it, but to balance it, tone it down and let it react to the environment in a normal way. Unfortunately, allergies are often the most difficult disease to treat, even with holistic or natural medicine. This is partly due to the fact that the immune system is so complex we only understand a part of it. Also, because of its complexity, it is not always easy to figure out what exactly needs to be done to balance it, and we do not have the extensive (and expensive) lab tests for horses that humans have.

A simple blood test that looks at white blood cells can tell quite a bit about the immune system. The white blood cells count (WBC on your test paper) shows part of the immune system. Often the WBC will be low or show that some of the different types of WBC are out of balance or too high. To learn about lab tests with human data (the concepts are the same with equine blood, just the numbers are different) see Interpretation of Lab Test Profiles. Many veterinarians pay little attention to results that are within the normal range but are on the very low or very high side, while others, especially the holistic vets, look more closely at the imbalances. With a chemistry screen blood test you can look at the liver, but unless you have significant liver disease, you will not see anything wrong.

Treating allergies is more complex. Management is important, whether your horse needs his hay wet, needs to be outside more if he has respiratory allergies to dust or mold in a barn, needs to avoid certain foods (which you are already addressing), needs to be inside during the dawn and dusk hours when the culicoides midges are biting on the midline of the belly, etc. Each horse is different in his needs, so where wetting the hay may work brilliantly for a horse who is allergic to the dust in the hay, another horse will either hate wet hay or it will have no effect on his allergies, in which case there is no need to wet his hay.

Many horses are allergic to pollens or molds that we have no control over, so short of moving to a state with a totally different plant and pollen profile, you are stuck with trying to help the immune system cope with the allergens. Conventional medicine has a few drugs to offer, but many have side effects, which can be serious. Many of our horses are overweight and could be insulin resistant (search for "laminitis" in the EquiSearch.com search bar to find related articles). Those horses are at great risk of developing laminitis if given the steroid drugs such as dexamethasone, which are commonly used to treat both respiratory allergies and skin allergies.

One simple ingredient that helps many horses with allergies is flax seed. It has many immune regulatory abilities; it is anti-inflammatory; it helps insulin resistance (so no need to worry about feeding it to fat horses) and it has been shown to help support the immune system when allergies are present. You can feed it whole (most horses digest the seeds well) at about 6-8 ounces twice a day (this is a high dose for allergies), or you can feed stabilized, ground flax at about 4-6 ounces twice a day. If you grind it yourself, you must grind, feed it immediately and clean your grinder since it will go rancid rapidly. Ground flax that has not been stabilized naturally should not be fed. Flax or hemp oil (an excellent oil similar to flax, but even better) can be fed instead of the whole seed, though it needs to be refrigerated in warm weather.

Vitamin C is another immune regulator that can be supportive, especially for lung allergies with difficult breathing, coughing or heaves. Generally horses like the taste, and it is not very expensive. The dose is usually about 4-5 or 6 grams per day. Some people use more, but I find that this dose works well. Many immune system regulators are expensive, so you need to be selective about which ones to pick (a sample of what is available is on my website), however, they are also other useful products, such as ImmuSyn. Antioxidants such as Vitamin E, selenium and zinc are all useful supplements. Most high quality antioxidants like alpha lipoic acid, co-enzyme Q10 and bioflavonoids like Citrus C/Q are helpful. If the company sells them cheap, they are likely not worth the money. Be sure to use a good probiotic, since about two-thirds of the immune system lines the gut wall, and you want to be sure the good bacteria are healthy.

A veterinary acupuncturist can examine your horse from a Chinese medicine perspective (see Alternative Healthcare Organization Links). There are several acupuncture meridian imbalances that can trigger allergies or be present in allergic horses. One is the liver acupuncture meridian, which can be diagnosed with the acupuncture exam. Other meridians could be involved as well, including the lung and heart. Acupuncture itself is very helpful for horses with lung allergies, but less so for skin allergies. However, Chinese herbs are very helpful for both skin and lung allergies, as well as food allergies where you may have diarrhea or constipation as the main symptom.

Homeopathic medicines are very helpful in allergies. Since these are difficult to treat, you need to work with a veterinary homeopath who can ask detailed questions about your horse and his symptoms. What makes the symptoms better or worse? Are they seasonal, or is the season getting longer each year? This doctor will ask a lot of questions to help get to the appropriate remedy. Many of my most successful cases, especially for itchy skin, have been treated homeopathically. Western herbs can also be helpful, though in many cases I find horses need the more specific help from the Chinese herbs and homeopathics.

The treatment of allergies requires patience and may need several treatments or courses of different herbs or homeopathics. Some horses need a bit of everything. Many allergic horses need support year after year during their bad season, though generally I find that overall each season gets shorter and less symptomatic when we have the right combination of immune ingredients.

Dr. Joyce Harman is a veterinarian and respected saddle-fitting expert certified in veterinary acupuncture and veterinary chiropractic; she is also trained in homeopathy and herbal medicine. Her Harmany Equine Clinic is in northern Virginia. Visit her online shop.

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Do you have a veterinary or saddle-fit question for Dr. Harman? Send it to asktheexperts@equinetwork.com. Check back for her answers on EquiSearch.com.

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