Equine allergies

Atopic dermatitis is an allergic reaction to environmental allergens such as pollen, dust mites and insects that come into contact with the skin.

This can be seasonal and dependant on the allergens present in the horse’s current environment. Some horses may show signs in summer when allergens such as trees, grass and pollen are more common. However, other horses are allergic to dust and forage mite allergens which are more common in indoor environments with poor ventilation.

Bacterial dermatitis is an allergic reaction often known as mud fever or rain scald.

Insect bite hypersensitivity, also known as Sweet Itch, is an allergic reaction to bites from Culicoides midges or other blood sucking flies and insects. Individual horses will display various signs and the rate of recurrence will vary based on the severity of the condition.

Excessive itching, also known as pruritus, is the most common sign but you may also see:

• Skin flaking
• Hair loss due to intense itching
• Hives (urticaria) – lumps which may or may not be itchy
• Discharge of pus, fluid or blood

• Nasal discharge
• Sneezing
• Coughing
• Wheezing
• Difficulty breathing
• Horse rubbing their nostrils against their leg or an object at an increased rate
• Poor performance

For this, potential triggers such as a bedding type or certain feeds, are removed under guidance from a vet. Improvements shown by the horse following the removal of a potential trigger will help indicate the type of allergen.

This usually involves clipping an area on the horse’s neck before injecting small amounts of an allergen, in liquid form, and then recording if there’s a reaction. Horses that are sensitive to an allergen will show stronger positive reactions such as swelling and hives in the area that they were injected¹. This enables identified allergies to be used in immunotherapy or other treatment plans.

• Minimise dust by using good quality bedding. If rubber mats are used in the stable, the BHS strongly advise that a good layer of bedding material is added on top of the mats, as this will help soak up urine and contain droppings
• Carry out daily chores such as mucking out and sweeping whilst the horse isn’t in the area
• Wash rugs and saddle pads to reduce dust mites
• Carry out feed checks to prevent feed wastage and mould spores, ensuring all old feed is used before opening new
• Maintain turnout during the winter months to provide the horse with fresh air, away from the stable environment.

• Involves feeding or injecting small amounts of an allergen, to the affected horse, increasing the amount each time.
• Using the feeding method daily is easier for owners and seems to be as efficient as the injections, which must be given by a vet³.
• This aims to improve the horse’s tolerance to the allergen and reduce the symptoms. However, it takes several months for results to be seen³.

• This medication blocks the action of histamine, which is the chemical in the body that triggers an immune response and reduces the severity of allergic reactions⁴.
• Provides a non-steroidal option that can be used long-term under vet supervision.

• These medications (often corticosteroids) are often given to horses suffering from skin reactions and have proven effective in controlling itching and hives. They are usually given daily until symptoms reduce and then gradually decrease to alternate days at the lowest dose needed to keep the horse reaction-free⁵.

• Products containing aloe vera and oatmeal may also be beneficial alongside regular grooming to remove dust and dirt from the coat.
• This will also help owners monitor the condition of the horse’s skin.