Like humans, horses can suffer from allergies, whether they’re triggered by the environment, their food, or something else. These horse allergies can cause anything from discomfort to severe illness. Luckily, serious and life-threatening reactions are very rare, but many horses can be mildly irritated by common things like insect bites.

We’ve put together a handy guide to understanding and treating horse allergies, from knowing the causes to spotting the symptoms and more. If your horse has an allergy it’s not the end of the world – and with a few adjustments, it’s likely that they’ll be as happy as ever!

Why do horses have allergies?

Allergies in horses work in the same way as human allergies. When a horse has an allergic reaction, their immune system has an exaggerated response to something – for example, pollen. We know that pollen is harmless, but your horse’s immune system responds by putting up all its defences. Instead of destroying the ‘threat’ (in this case pollen), the response can damage the horse’s body. Histamine is the most common chemical that bodies release during an allergic reaction – that’s why we take antihistamines for things like hay fever. Allergies in horses can take months or years to develop. When you buy a new horse, even after thoroughly checking their medical history, they may turn out to have an allergy.

To help support your horse’s immune system, why not try Vetroimmune Equine? It helps support the body’s natural immunity during periods of stress and poor health, and can be added to the diet of any horse.

Causes of horse allergies

  • Food allergens are unusual, but if your horse has a true food allergen, it can cause anything from hives to difficulty breathing. Bear in mind that it might seem like they’re allergic to something when they’re not – if they show symptoms when they’re being fed, it might be the dust from the hay that’s affecting them!
  • Insect bites are normally to blame for skin reactions, including hives. It may be that your horse isn’t allergic to the insect, but has simply suffered irritation because of the bite itself. In either case, these reactions can be uncomfortable but are rarely serious.
  • Environmental causes include anything that your horse inhales. Unfortunately, stables are full of potential allergens and they’re nigh-on impossible to eliminate completely. They include dust, pollen, and mould.
  • Contact triggers are allergens that cause a reaction when they touch your horse’s skin. These can include plants or cleaning substances (for example, horse shampoo)
  • Medicine is another potential cause of allergic reactions. These can include vaccines and performance drugs. If your horse is very allergic to a particular drug anaphylactic shock may occur, but this is highly unusual!

Symptoms of horse allergies

  • Hives are soft swellings that are usually about half an inch in diameter, although they can grow larger and even merge together. They’re not usually that itchy, and may well disappear after a few hours. Common sites are the sides, shoulders, neck and chest of your horse.

  • Itchiness is another sign of horse allergies. The most common cause of itchiness is ‘sweet itch’, which refers to an allergic reaction to midge bites. This allergic reaction can create an itchy rash, which will lead your horse to rub the affected area. Unfortunately, this can sometimes lead to an infection.
  • When an allergic reaction occurs, your horse may have difficulty breathing due to a narrowed air passage. This will sound like wheezing or coughing, and may be accompanied by nasal mucus.
  • Anaphylaxis is a very extreme, and fortunately unusual, reaction. Anaphylaxis occurs quickly, usually in response to an allergy to which your horse is extremely sensitive. His blood pressure will drop and he will struggle to breathe. This can result in shock and death.

Reactions like hives, which are not usually severe, may occur slowly and often go away by themselves. Nevertheless, if they remain for a long period of time (usually more than a day) then seek advice from your vet.

Treating horse allergies

If you suspect that your horse has had an allergic reaction, ask yourself if anything in their environment has changed. Have they tried a new food? Are there more insects than usual?

Your vet will be able to help you pinpoint the cause of their allergic reaction, but it helps if you have a good idea to begin with. Once you know what has caused the reaction, there are several ways to help manage their allergy.

  • Banning the allergen is the simplest method of controlling an allergy, and in many cases nothing more is needed. For example, if your horse has an allergic reaction to something in a certain brand of food, make sure you choose a brand without that ingredient. Similarly, if contact with a certain plant has caused a reaction, vigilantly make sure that your horse is not exercised in an area with these plants.
  • Medical treatment can help in cases where the allergen can’t be avoided. For example, no matter how carefully you clean your stables, if your horse is allergic to pollen they are bound to have a reaction in the summer. For these types of horse allergy, a regular allergy injection can help. Your vet may also be able to recommend other medical treatments.
  • Avoidance can help control exposure to the allergens that will never be completely cut out. For example, if your horse is allergic to pollen, you might consider stabling them somewhere farther away from a field of the offending crop! Similarly, if your horse has a mild dust allergy, keep the stables clean and make sure they are let out to pasture as often as possible.

If you suspect that your horse is allergic to something, the first thing you should do is consult your vet. Make a note of anything that has changed in their environment, what the symptoms are, and how long they have lasted for. Even if the reaction seems very milk (for example, hives that disappear) it’s worth checking with your vet for peace of mind.