What are Allergies?
Allergies in horses requires dedicated management to reduce the animal’s exposure to the allergen. In order to discuss the best plan for your horse it is vital that you contact your veterinarian.
Allergies in horses can occur following exposure to an allergen such as mold, fungus, or a food. This can be through contact on the skin, through the gastrointestinal system, or respiratory tract and may lead to histamine production and inflammation. This condition can cause numerous symptoms such as hives or itching skin, and respiratory symptoms such as coughing or mucosal discharge.
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Symptoms of Allergies in Horses
- Hives may occur which commonly present on the back, flanks, neck and legs
- These hives are soft, raised welts which should indent under pressure
- Intermittent coughing which may progress to deep, frequent coughing
- Nasal discharge
Causes of Allergies in Horses
The causes of allergies vary as horses can be allergic to various substances. In some horses, airborne allergies may occur following exposure to dust, mold or fungus, other causes may be exposure to shampoos or lotions. This condition is caused when the horse’s immune system, which usually is responsible for protecting the body against antigens, overreacts following exposure to the allergen. This can cause release of inflammatory chemicals in the body and lead to hives, rashes, and bronchoconstriction and respiratory symptoms.
Food allergies occur when the antigens breach the intestinal mucosal barrier in the gastrointestinal system and are exposed to white blood cells, triggering an immune response.
Diagnosis of Allergies in Horses
Your veterinarian will first observe your horse from a distance to check for abnormalities that may not be visible while restrained such as gait, respiration and demeanour. Your veterinarian will then auscultate the lungs, heart and digestive system. Often a diagnosis of allergies is made through clinical signs, although if your horse is suffering from hives the veterinary team may carefully examine the skin and may take scrapings to rule out parasitic, fungal or bacterial infections. Your veterinarian may also choose to take a collection of fluid sample via bronchoalveolar lavage to examine inflammatory cells.
If a food allergy is suspected, an elimination diet should be fed to your horse. This is done by providing a diet that does not include any items previously fed; this diet should be given to your horse for 3 months, with careful monitoring of clinical signs. Following this, if all symptoms have been eliminated, the foods that were previously fed should be introduced individually. If symptoms return following a food being given, then that food should be removed once again, if signs once again subside the food is likely the culprit.
Treatment of Allergies in Horses
The treatment given will mainly be supportive to reduce symptoms, with emphasis put on the importance of environmental or dietary management for long-term recovery.
- Antihistamines may be given for itching
- If your horse is suffering from hives due to allergens in the environment topical medication may be given to control itching
Bronchodilators may be given if the allergies are causing respiratory symptoms reduce inflammation, clear mucus and relieve the muscles in the airways, which may allow your horse to breath easier. Corticosteroids reduce or prevent the body from releasing inflammatory chemicals, therefore reducing inflammation.
Recovery of Allergies in Horses
Your horse’s long term recovery will depend on the management to reduce the exposure to the allergen.
Your horse should be kept on a diet free of the allergen identified, good management by strict avoidance will often lead to full recovery of symptoms, however, in some cases horses may develop new food allergens over time.
Ideally your horse should be kept outdoors with access to fresh air and away from dust roads. However, if this is not possible the stable should be adequately managed to provide your horse with clean, dust free air.
- Ensure your horse’s environment has good ventilation, in some cases ceiling fans with particle filters to circulate the air may be beneficial
- If your horse is suffering from allergies to dust provide open air therapy and house outside if possible, if allergies occur following pollen exposure consider keeping inside during high pollen months
- As hay, grain and bedding may cause mold spores and particles to be released into the area, store these in a building away from your horse
- Provide your horse with rubber matting or shaved paper for bedding rather than straw or wood shavings to reduce inhalants
- Feed your horse a dust-free diet if possible
- As poor quality hay can often be damp, causing mold, ensure only good-quality high with low moisture content is provided; good quality high should be sweet smelling, free of mold and dust, cut before maturity and green in colour
- Consider keeping a diary documenting relapses, repeated relapses on days of high pollen count may indicate pollen as a culprit