Allergy type reactions in horses


“There have been a number of attempts over the years to establish a specific test for allergic responses in horses but none appears to have been accepted as being definitive.”…“To date nothing has been proven about dietary allergies in horses and it is probably not justified to suggest that even most cases are due to diet problems.” Dr.D.C.Knottenbelt DVMS, BVMS, MRCVS The 3 rd International Conference on Feeding Horses – Dodson&Horrell Ltd.

Horses and ponies evolved to wander over many miles finding the balance of nutrients they required for health, healing and development from a variety of grass species and herbage growing in a variety of soil types. Because mankind expects work from his horse and keeps him confined, for convenience, horses are offered extra feedstuffs to provide the energy for work.

If the energy and the protein, vitamin and mineral requirements are not met the horse will use his body stores, and so loose weight and condition. The horse would then be offered feedstuffs that should enable him to put on weight.

Grain has been the traditional agricultural feed for fattening livestock and, as the horse’s digestive system has evolved to digest a certain amount of seed from its grass intake, a limited amount of some cereals has been found to be effective. The traditional cereals used to feed horses are oats (the most easily utilised by equines), maize, barley and sometimes a little cooked wheat.

Some horses have been found to show an “allergy-type” reaction to barley in any form. There have been cases where horses have tolerated a high barley intake only to show a reaction when bedded on barley straw!

Reaction, shown by erratic behavior, lumps & bumps or filled legs, can occur after many years on the same barley-loaded diet. Sometimes it appears that the horse’s system can no longer cope – as when barley is removed from the feed the condition subsides.

In some cases horses have shown a mysterious reaction, although on a carefully balanced diet, and when barley was removed from the diet the problem subsided. When put back on the normal ration later in the year there was no adverse reaction to it. Eminent researchers suspect that for some animals a minor intolerance of barley pre-disposes a reaction to another allergen, which may be temporarily in the horse’s environment, for example certain types of plant pollen.

Some materials offered for use in formulating diets for horses are suspected of causing ‘allergy type’ reactions. As with anything – excesses can be dangerous, for example too much iron can interfere with the utilisation of other nutrients, so care should be taken when using seaweed in the ration.

As all feed passes through the digestive system it is broken down into simple sugars so that it can be absorbed. Horses evolved to digest the variety of sugars found in grass and plant material. But an excess of sugar has been suspected, by some, of causing a reaction, suggesting that if too much molasses is fed it may cause a problem. However molasses has been found to be a very useful part of many rations for generations of horses and would appear to cause no problem when fed with discretion.

A balanced ration formulated from materials that have been tried and tested by horses through the years, and providing all necessary nutrients, should avoid most allergy-type reactions – provided not fed to excess!