Allergies and Intolerances
Human allergies are visibly on the rise these days, however it is not clear whether this is due to greater awareness or more actual cases developing. Similar could be said for equines and either way, as more people focus on the finer points of the horse’s diet, more allergies and sensitivities are being discovered. “Generally horse owners are becoming much more aware of the horse as an athlete and its nutritional needs,” says Colin Price of Mitavite UK.
“Certainly there has been much in the press about human intolerances and nutritional advances, likewise people are thinking more about what is in the feed they are giving their horses. Mitavite is educating consumers to read the packaging, know what they are feeding and the effects it has and feed a regular balanced ration with forage and fibre.” However, Dodson & Horrell nutritionist Dr Teresa Hollands says: “True food allergy is less common than popularly believed.” She emphasises that food intolerance is not the same as an allergy: “Intolerance reactions are ‘non-allergic’ hypersensitivity reactions which have reproducible adverse reactions, but they do not involve the immune system. Diarrhoea might be a good example of non-allergic hypersensitivity as long as sudden changes in diet or stress have been ruled out.”
Dengie nutritionist Katie Williams points out that the Dengie feed helpline has found more people are reporting allergies and believes that modern management practices are the cause: “Research in humans has shown that increased omega 6 intake and low omega 3 intake puts the body into an ‘inflammatory’ state. As cereals have higher levels of omega 6 than 3, a cereal based diet can upset the ratio in the total diet, which may predispose horses to allergies.”
Diet dilemmas
Horses can be allergic to various components within the feed, and an allergy or sensitivity can develop later in life. Often, the horse can be intolerant to cereals such as barley, as well as wheat, maize and oats. Some horses can also react to peas, soya oil, garlic and any number of other ingredients commonly found in concentrates. This does create a problem: although feed is clearly labelled with ingredients it is difficult to ascertain the true allergen in the diet. Dengie nutritionist Katie Williams says: “The ingredient I most often come across causing a problem is barley, mainly causing urticaria. The symptoms usually disappear once barley is removed from the diet.”
One way to discover the trigger within food is to put the horse on an elimination diet, which carefully removes and reintroduces every feed ingredient and noting when the reactions stop and flare up. When embarking on an elimination diet it may be necessary to cut down on exercise, as the energy intake will be varied and owners must remember to make dietary changes slowly. An elimination diet is an effective way to determine the problem allergen. When eliminating various feed components it is important to continue until all individual substances have been eliminated and then reintroduced. If a reaction occurs when the ingredient is reintroduced, then the horse has an allergy or sensitivity to that product, but there may be more than one trigger so the eliminations and reintroductions must continue. Horse owners should also remember that any treats, supplements or forages could also trigger a reaction. Symptoms of a food allergy or sensitivity could be urticaria, other rashes, swelling of the face or poor digestion and horses with a feed intolerance may be susceptible for many months or even years.
Scary skin
Urticaria is a startling skin condition that is rarely life-threatening and appears as lumps or weals all over the horse’s skin. Urticaria can be a reaction to any number of airborne or feed allergies. Also known as hives, the lumps can occur quite suddenly, and often the horse feels no ill-effects, however if the lumps do not disappear within a few days, or keep reoccurring, veterinary advice should be sought.
Urticaria is an obvious sign of allergic reaction and sensitization; unfortunately it can be very difficult to discover the initial trigger. As the allergen is so difficult to ascertain, it is best to look at all options, however the symptoms should subside quite rapidly. If they reoccur regularly it is worth taking a close look at the horse’s lifestyle and feeding regime, and making adjustments. Management aspects to be considered would be: medication and drugs, such as worming and vaccinations; feeding – any new dietary elements, supplements etc; physical factors such as extremes of temperature; contact factors such as new saddle cloth or fly spray; seasonal factors such as insects and pollen.
Sweet itch
A strong allergic reaction or hypersensitivity to the Culicoides midges, this common skin disease affects approximately 4% of horses and ponies in the UK.
Symptoms include extreme itching and rubbing, resulting in damaged hair and skin, as well as flaky scurf, weeping sores and possibly infection.
Much of the treatment for this condition involves controlling the environment, for instance stabling the horse during the day and avoiding marshy areas. However, there is a huge range of products to help relieve the problem. Sweet itch will be looked at in greater depth in a future Let's Talk Horses editorial.
Respiratory problems
COPD, more recently known as ‘recurrent airway obstruction’ (RAO), usually affects stabled horses and the symptoms are a chronic cough, poor exercise tolerance and nasal discharge. In more severe cases breathing can be laboured and heave lines can form due to the extra muscle exertion required to breathe out. RAO is usually caused by a constriction of the bronchioles in the lungs, triggered by an allergy to fine dust particles such as fungal spores from hay and straw or pollen.
Treatment involves maintaining clean air for the horse and it is important to remember that RAO is an allergic problem, therefore treatment can simply be avoiding contact with trigger factors. However, it is clear that this is not an easy task. Katie Williams says: “Modern life is most probably affecting horses just as it is humans, greater exposure to pollutants plus the way we keep our horses stabled for longer in the winter doesn’t help their respiratory systems.”
To help treat respiratory problems there is a wide variety of treatments in the form of liquids or feed additives, as well as dust-free bedding and feed. There are many bedding options available that can help to reduce airborne dust and moulds, which can not only affect the horse’s breathing, but can also make the owners wheezy. Rubber matting and dust-free shavings are popular but it may be worth investigating paper, as it is cheap, recycled and completely dust free.
All hay fed should be the best quality possible, but dust and spores will always be a problem with dry hay. One option to reduce dust is to soak it for at least half an hour so the spores swell and stick to the hay. Steaming hay can also reduce dust and spores, but the resulting hay is more sweet smelling and maintains more of the nutritional value than soaking it. Haylage is an excellent alternative and is much less dusty, but not dust free. For particularly sensitive horses a forage replacer may be required, such as a chaff or high fibre cube.
Some treatment options are available to open up the airways and improve breathing but are usually veterinary prescribed, such as corticosteroids or bronchodilators. Suitable supplements often contain garlic, which has been shown to have an inhibitory effect on bacteria that impacts on the equine respiratory system and also works as an expectorant, helping to eliminate mucus that can build up. Cough syrups may soothe the symptoms but the only way to protect the respiratory system is to control the environment.
Allergy testing
Various tests can be used to work out the problem allergen, but all are currently carried out by vets. A complete blood cell count could be done, or a nasal smear, to measure white blood cells – an increase in white blood cells means the body is trying to fight off a foreign invader such as an allergen. A radio-allergosorbent (Rast) test measures antibodies in the blood and can help ascertain the specific allergen.
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