Feed allergies are a common concern amongst many horse owners, particularly in relation skin conditions such as ‘lumps/ bumps’ and hives. So, what is an allergy and can feed really be the cause?

Example of lumps under the skin

In truth, feed allergies in horses are rare and in fact, the term ‘allergy’ is one that some believe is overused even in people.

Allergies are caused by the immune system overreacting to a type of protein called an allergen - which in both non-allergic horses and people is generally harmless. This considered, allergies to feed are caused by a specific type of protein rather than oils or sugars as is commonly thought.

If, however, you do suspect that your horse may have a feed allergy, an elimination diet is by far the best action.

This will involve removing all hard feed from the diet for a minimum of four weeks, monitoring the ‘reaction’ and then reintroducing feeds one at a time to see if the reaction returns. If it does, this would suggest that the horse is allergic to something in that feed and alternative can be tried.

Whilst allergy tests are available, the results are unfortunately unreliable in horses. In one study (Dupont et al 2014), 2 serum (blood) allergy tests were performed on 17 ponies and whilst 35% tested positive for feed allergies, none of the ponies reacted to all of the same allergies in both tests. Furthermore, eating the feeds they tested positive to for 14 days did not cause any clinical signs of an allergic reaction or result in any changes to inflammatory blood markers.

“Lumps and bumps” are one of the most common reasons that feed allergies are suspected in horses when in reality, diet (feed or forage) is unlikely to the culprit. However, finding the true cause can be notoriously difficult and very frustrating for owners. Temperature (particularly in spring and summer months), clipper oil, mites in forage/bedding, detergents used to clean rugs and numnahs or pollen could be responsible and changes to feed often prove to be coincidental.

In fact, seasonal allergies don’t just affect the horse’s skin and at this time of year, pollen and oilseed rape in particular can challenge respiratory health in some horses and ponies. If this sounds familiar always seek veterinary advice as your first port of all call but following this, a respiratory supplement high in vitamin C may be helpful.

For more information about feed-related allergies, please don’t hesitate to contact one of the nutritional team at SPILLERS who will be happy to answer any of your questions.