Warmer weather means the return of allergy problems for many horses, including respiratory allergies, insect-bite allergies, even headshaking in some cases. There are a number of non-drug options that can help these horses greatly, but waiting until symptoms appear isn?t one of them.
You can boost your horse’s own defense mechanisms, but you’ll need to start immediately. Nutritional and herbal approaches take a while to reach effective levels in the tissues. Even antihistamine drugs are far more effective if they’re on board before the reaction starts. Corticosteroids and bronchodilators can work quickly, but these are heavy hitters and you might be able to avoid them if you get a head start on the process.
What Causes Allergies’
Researchers are becoming convinced that the tendency to develop allergies has a genetic component. But it’s not specific allergies that are usually inherited. it’s actually the tendency to develop allergies in general. This likely is caused by the way the immune system is ?wired? to react to challenges.
The exposure of the immune system to anything that isn?t a basic component of the horse’s body will cause a reaction. The most familiar examples are viruses and bacteria, but any foreign protein or complex carbohydrate could trigger reaction.
Obviously, we can’t change a horse’s genetics, but we can dodge making things worse. In particular, we can avoid nutritional deficiencies that impair the horse’s ability to keep inflammation in check and protect the immune-system cells so they can work properly.
Nutrition.
Of course, there are nutritional approaches for specific types of allergies, but before you tackle these you should be sure your horse isn?t suffering from some basic, common deficiencies, including copper, zinc and selenium.
Copper and zinc have many functions in the immune system, including the superoxide dismutase enzymes, which are important antioxidants. Deficiencies are extremely uncommon, and supplemented grains or the so-called balancers may not get the job done because sometimes they also contain high levels of competing minerals that are already high in the base diet.
A ?competing mineral? is one that inhibits the absorption of another. that’s why minerals need to be fed in balance with one another. Be especially suspicious of this effect if your horse also has hoof quality issues or bleaches out easily. See our May 2011 article on coat bleaching for additional information.
Selenium is deficient in many areas. Check with your veterinarian about your area, if you’re not sure. You can also have your horse’s whole-blood selenium levels checked. An intake of 2 mg/day from selenium yeast for a 1,000-lb. horse is sensible in most areas.
Respiratory Allergies.
Spirulina platensis is a species of blue-green algae (other blue-green algae do not have this effect) which has proven effects on the immune system. Specifically, it decreases levels of histamine and IgE in classical allergic reactions, markedly reduces inflammation and also inhibits delayed-type allergic reactions.
Many horses with reactive airway disease/?heaves? (see August 2010) have been able to come off medications when getting Spirulina.
it’s also highly effective for headshaking that is caused by upper respiratory allergies. The effective dose is 2 grams/100 lbs of body weight, twice daily. Since 20 grams of Spirulina powder is about an ounce, by volume, you should give your horse two tablespoons of Spirulina twice a day. Spirulina is also effective in reducing itching and inflammation of skin allergies in about 50% of horses (more on skin problems below).
When bronchospasm persists despite Spirulina, add Gynostemma pentaphyllum (Jiaogulan), at 2000 mg (2 grams), given twice a day with the Spirulina (this means you give your horse 1?? to 2 teaspoons per day for a 1,100-lb. horse).
Vitamins C and E are important antioxidants. In horses with reactive lung disease, vitamin C levels usually are considerably lower than in healthy lungs.
If your horse is on good pasture, He’s already taking in generous amounts of these two vitamins and won?t benefit from supplementing. However, both these vitamins are lost rapidly when hay is cured, and they are not stable for long in feeds or multi-ingredient supplements.
Powdered vitamin E is poorly absorbed unless mixed with oil first or with fat in a water-soluble powdered form. The easiest way to supplement it is to just feed human-grade soft gelcaps containing E and oil. The vitamin E dose for high-requirement situations such as this is unknown, but it’s likely around 200 to 500 IU/100 lbs of body weight (read the label on the bottle to determine the IUs in each gelcap). Pure vitamin C can be added to feed as loose powder, and you can feed human or horse products. Dose is 1 gram/100 lbs. of body weight.
Owners of horses with respiratory allergies claim that MSM helps their horses. If you want to try MSM, the usual dose is 10 to 20 grams/day for an 1,100-lb. horse (that’s 1 to 2 tablespoons).
Hives, Sweet Itch and Midline Dermatitis.
Whether a true allergy or exaggerated reaction, these skin problems are common. Histamine is almost always involved, and the immune system is shifted toward an emphasis on inflammatory and allergic reactions.
Chondroitin sulfate, the same as used in joint supplements, can be very helpful in suppressing allergies. The effective dose is 2,500 to 5,000 mg/500 lbs. of body weight, given twice a day. Laboratory studies have proven that chondroitin sulfate suppresses the development of IgE antibodies, the antibodies of allergic reactions, and also suppresses inflammation. A combination of chondroitin and Spirulina works particularly well. Like most things, it is most effective if started before the allergy season begins.
A 2002 Canadian study demonstrated that horses fed milled flaxseed had decreased reactions to Culicoides extract. Culicoides is the midge that causes sweet itch. However, it took longer than three weeks for this effect to kick in, another example of why you need to start early. The amount fed was 1 pound per day per 1,000 lbs. of body weight, which is a lot of flaxseed by volume for a horse to consume.
If your horse’s skin reactions are restricted to the midline and front half of the body, you may be dealing with migrating larvae of the neck threadworm, Onchocercac cervicalis. The adults live in the nuchal ligament of the neck and cannot be killed by deworming. They release tiny microfilaria that travel to the midline of the belly where they are picked up and passed to other horses by biting insects. These microfilaria may also cause small bumps under the skin and circular areas of hair loss on the face.
Deworming with ivermectin (the regular equine paste) kills the microfilaria. Horses with large burdens may actually worsen due to increased inflammation and itching after the first deworming. Repeat at three- to six-week intervals during the warm months.
Bottom Line.
Getting on top of allergies requires a proactive approach. If you can’t isolate the source of the allergy and eliminate it, you need to anticipate that it’s likely to occur and begin supplementing the horse to arm his body for defense.
