Summer shouldn’t mean nonstop itching, rubbing and biting.

If the thought of sunny summer horseback riding is clouded by memories of bumps, hives, sores, itching, coughing, wheezing, runny eyes, and headshaking, take action now. If you wait for the symptoms to appear in your horse, you’ll be in for a long, uphill battle for the duration of the allergy season. 

Allergies
An allergy is an exaggerated immune system reaction to something in the environment that normally shouldn’t cause any detectable response. 

Genetics do play a role, but family history doesn’t automatically mean the horse is doomed to allergies. Respiratory allergies, for example, may develop following immune-system activation by a viral infection and persist long after the infection has been cleared.  Nutritional factors may play a large role in determining how your horse can control allergic reactions.

Diagnostics
Allergy testing can help identify triggering substances so that you can try to avoid them and help identify specific allergens that make it possible to do desensitization injections.

Horses have access to two types of testing, intradermal injections and blood antibody tests (RAST testing).  False negatives and false positives can occur with both.

False negatives are most likely when testing is done during a time when symptoms are quiet, but strong allergies are still likely to be detected at this time and testing during an asymptomatic period can cut the number of false positives obtained. 

False positives are most likely when testing is done while the horse is actively having problems. Reactions are generally considered false positives if they aren’t consistently present, or disappear as symptoms quiet down, and are believed to arise because of the overly sensitive nature of the immune system during allergy attacks.  It’s still helpful to know the “false” positives, since avoiding those substances can help calm down the responses in general.

When allergy testing does identify the major allergic triggers, a series of densensitizing injections can be helpful. However, the process of testing, formulating the injections and the series itself is expensive, and should only be done by an expert in this field. 

Put It To Use • Consider allergy testing so that you can identify triggers. • Consult with a veterinary allergy expert about the feasibility of desensitization injections. • Maximize your horse’s immune system with careful attention to essential fatty acids and key vitamins and minerals. • Use Spirulina or plant-based antioxidant supplements for further control. • Avoid stress and minimize exposure to allergens/irritants. • Discuss with your veterinarian which drugs might be used if allergies get out of control.

Beware Immune-Support Supplements Since allergy involves the immune system, it might seem like a good idea to give the horse a supplement designed for immune system “health.” However, this could easily backfire.  Immune-system supplements generally work by activating the immune system, but in allergy the problem is already related to overactivation.

Chemical Allergies Environmental chemicals are increasingly recognized as a source of allergies in people.  Diagnosis is still far too expensive to be part of a routine allergy workup for horses, but chemicals can sensitize your horse, too. Chemical allergies may be at work in cases that are difficult to control.  Exposure may come through inhalation or ingestion.  Be suspicious if: • Allergy symptoms worsen when neighboring farmers spray their fields. • Your horse lives in an area where air pollution is a heavy problem. • The water is from a well that is not treated or tested. • Allergy symptoms worsen on alfalfa but allergy testing to alfalfa is negative (alfalfa fields are more likely to be treated with pesticides than grass hay fields). • Your horse developed allergy symptoms after a move but without any change in diet. Industry-related airborne chemical exposures can be minimized if you: • Keep your horse inside when nearby farms are spraying. • Avoid chemical insect-misting systems in the barn. • Don’t use untested, untreated well water. • Feed grass hay. • Avoid brans, unless certified human-food grade, since chemicals are in highest concentrations in the outer layers of grains. • Feed organic grains or hulled, “naked” oats.

Feed To Fight Allergies
We can make a difference for our horse by making sure the horse is provided with the correct nutrients to allow his immune system to implement counterbalancing responses. 

Like all body systems, the immune system has cells that both initiate inflammatory/allergic-type reactions and cells that keep those reactions in check.  Unfortunately, many of the nutrients that are critical to maintenance of good anti-inflammatory responses are the ones most commonly deficient in equine diets.

Dietary fat plays a role.  Saturated fats, like the animal fat present in dry weight-gain supplements, and omega-6 fatty acids, which are the predominant fatty acid in common equine feeds and most liquid fat supplements (e.g. soy oil, rice bran oil), favor inflammatory pathways.  The omega-3 fatty acids are anti-inflammatory but are more difficult to incorporate in the horse’s diet.

Horses need both omega-6 and omega-3 acids, but the allergic horse can benefit from specific supplementation with the omega-3s.  A study performed by the Nutraceutical Alliance in Canada confirmed that supplementation with flax helps control the symptoms of Culicoides allergy (“sweet itch”).  To adjust your horse’s diet so that the fat intake helps him keep allergic reactions under control:
• Avoid animal fat and fat-added feeds.
• Supplement horses on predominantly forage diets with 4 to 6 oz.  of a blend of omega-6 and omega-3 fatty acid sources, such as a mix of stabilized rice bran and stabilized flax.
• Supplement horses on grain and hay diets with a flax-based supplement, 3 to 4 oz. a day.

Key minerals to feed include:
• Magnesium: Anti-inflammatory and antispasmodic. Magnesium is in low supply in many areas. Available in 20 to 50 lb. bags from feed mills, which is economical, or use the pelleted Quiessence (www.foxdenequine.com 540-942-4500, $27.50/5 lbs.).  Feed 5 grams/day, or as indicated by your hay analysis results (1 oz. measure of Quiessence or about half a tablespoon of powdered magnesium oxide).
• The trace minerals copper, zinc, manganese and selenium are critical to maintenance of good antioxidant/anti-inflammatory systems.  While manganese is rarely in short supply, deficiencies of the other three are common.  Hay and/or pasture analysis is by far the best way to determine which you need to supplement and by how much. We like Vita Key Antioxidant Concentrate (www.vitakey.com, 800-539-8482 $49.50/5 lbs.).
• Vitamin E. Vitamin C is abundant in fresh pasture, as is vitamin A. Good-quality hays also supply sufficient A in most cases. However, you should supplement vitamin E, at least 1200 IU/day for horses not in work, 2000 IU/day for horses being worked or fighting allergy symptoms. E is included in many vitamin/mineral products but will lose potency after six months. Supplement at least half of the vitamin E amount as either a pure vitamin E product, such as Uckele’s Liquid E-50 (www.uckele.com 800-248-0330, $18.95/pint). Feed ½ to 1 tsp./day. 
• B vitamins. The B vitamins are also important in maintaining the integrity of the skin and mucus membranes. Flaxseed and rice bran will provide fairly good basic levels of B vitamins, as do the vitamin/mineral supplements on our list.  For horses that obviously have problems with hoof quality/growth or skin flakiness/dull coats consider specifically boosting biotin, a B vitamin, intake. HorseTech’s Bioflax 20 (www.horsetech.com 800-831-3309 , $36.20/5 lbs.) does double duty as a source of both high-dose biotin and ground stabilized flaxseed.

We’re also impressed with the preliminary results of feeding Spirulina for allergy symptom control (see December 2004).  Horses with seasonal respiratory allergies may also benefit from additional intake of potent plant antioxidants from products like HemoCease (www.peakperformancenutrients.com 800-944-1984) or PhytoQuench (www.uckele.com 800-248-0330).

Consumer Alert: Avoid Kinesiology/Muscle Testing Kinesiology is a branch of alternative medicine that essentially says you identify substances that are harmful (including allergens) or helpful by putting them on a muscle, or having the patient hold them in their hand, then testing the muscles for strength/tone (a “good” response) or weakness (a “bad” response).  Some alternative practitioners are using a variation on this theme to “diagnose” horses by holding a substance in their outstretched hand, close to the horse, and asking the owner to try to push their arm down. Don’t buy into this. Several studies, done using self-proclaimed kinesiologists, many even in the setting of hospitals that use a variety of alternative health approaches, have found it to be unreliable and no more accurate than guessing.

Alleviate Symptoms
Runny Eyes: Red, irritating and tearing eyes are a common allergic problem in horses. Most cases are caused by insect irritation/sensitivity.  Your best defense against this is simple but underused—a well-fitted fly mask (see May 2004).  Even if there is an element of pollen sensitivity involved, simply eliminating the mechanical irritation from flies on top of that can drastically decrease the severity of the problem. Horses with pink skin around their eyes will also have an element of sun sensitivity adding to the problem.

When tearing and irritation persists despite protection from light and insects, there’s likely an element of pollen or airborne mold sensitivity. Soothe the eyes with either human eye drops, Farnam Clear Eyes (www.farnamhorse.com 800-234-2269) or use a tuberculin (1 cc) syringe to drop sterile saline solution across the horse’s eyes. 

For an extra soothing effect, keep your drops or saline in the refrigerator. Store in a self-sealing plastic bag to avoid contamination of the container with refrigerator molds, which may be invisible to the eye.

COPD/Heaves/Asthma:  Horses with lung allergies are particularly difficult to control because, in addition to specific allergen hypersensitivities, they’re also highly sensitive to dust, inhaled chemicals, and weather changes such as cold or high humidity with high levels of suspended irritants.  Careful attention to vitamin and mineral intake is helpful and should be maintained year round. Spirulina is certainly worth a trial. Avoid heavy exercise or other stresses at times of the year when the horse is most prone to attacks. Pelleted complete diets minimize dust exposure from feeds. Be vigilant about any types of mold, many of which you can’t easily detect. Avoid dusty bedding, like straw. Shake out any hay and soak it to reduce/eliminate dust.

Skin Problems: Most seasonal skin problems are related to insect hypersensitivities. Careful attention to diet and supplements can calm these reactions considerably.  Permethrin-based chemical repellents are the most effective across the board, but reactions can develop to these, as well as to “natural-ingredient” fly sprays. 

Use fly sheets and allow the horse free access to shelter to escape the pests.  Large fans positioned to blow across, or out, doorways may discourage many flying insects.

Sweet Itch/Midline Dermatitis Tiny biting insects, called Culicoides—aka biting midges, no-see-ums—cause a lot of misery for many horses and ponies. Icelandic ponies are particularly prone to the problem, but no breed is safe. Symptoms are raw, open, oozing and extremely itchy areas along the undersurface of the belly, and/or excessive mane or tail itching, also sometimes with open, oozing areas.  These tormenters are particularly difficult to control since they virtually ignore regular fly/mosquito sprays.  However, they are stopped by mechanical barriers and find camphor and phenol particularly offensive.  The recipe for a repellent and soothing formula we’ve found particularly effective is below. It’s also effective for other tiny insect pests, like chiggers. Sweet-Itch Remedy: Mix ¼ teaspoon of the human product Campho-Phenique (available in drug stores) and ¼ teaspoon of Calm Coat www.calmcoat.com, 888-396-0004) into a 13 oz. jar of petroleum jelly (Vaseline or a generic). The petroleum jelly provides a barrier, while the Campho-Phenique is a barrier, repellent, anesthetic/disinfectant. Calm Coat is thick, providing a barrier, soothing essential oils and repellent action. Generously apply to the affected areas two to three times a day or any time the horse becomes itchy.

Food Allergies
The role of food allergies in equine allergic symptoms is poorly understood.  Although allergy testing often shows reactions to hays and grains, there are no good studies regarding the responses horses might have to foods. 

In people, food allergies can cause immediate, life-threatening anaphylactic reactions with throat swelling, or less severe chronic symptoms which including respiratory problems, watery eyes, skin eruptions and/or itching, or digestive upset, nausea, diarrhea. 

It’s also known from research with other species that a history of any type of allergy, including inhalant allergies (e.g. to pollens or molds) increases the risk of having food allergies as well. 

When a horse with seasonal allergies turns up as positive for a grain or hay type fed year round, odds are this is either a false positive or a sensitivity that has arisen as a result of the primary allergy making him more reactive in general.  Either way, the wisest course of action is to avoid any foods that test positive at least when the horse is actively fighting allergy symptoms.

Obviously, if your horse’s hay and/or grain haven’t changed when summer arrives, these aren’t likely to be a major factor, but sensitivity to something in the pasture could be.  If you're fairly certain your horse's skin reactions aren't insect-related, try turning him out with a muzzle that prohibits grazing for a few days to see if it makes a difference. This would indicate an allergy to a plant in the field.