Does your horse develop a cough when you stable them in bad weather? Or become itchy if you rug them up? Although this could happen for a number of reasons, it may be that they are suffering from an allergy.
What is an allergy?
An allergy is when your horse’s immune system has an overreaction to what would normally be considered a harmless substance – this substance is known as an allergen. Instead of ignoring the allergen, their immune system gets it a bit wrong and views it as a threat. Exposure to the allergen therefore results in an increased production of something called IgE antibodies. Antibodies are made by white blood cells as part of the body’s defence against illness and disease. The IgE antibodies then trigger various reactions from other cells in the body which ultimately leads to the occurrence of the symptoms you see. The next time your horse meets the same allergen, their immune system is ‘primed’ ready and so the reaction is much quicker.
As the weather changes and more horses start to be stabled and rugged, indoor allergens can become more of a problem; this blog is going to look in detail at those allergens and suggest ways to avoid or minimise them.
For many owners stabling your horse will be, at some points of the year, unavoidable. Most stabled horses will be given bedding to lay on, as well as both forage and hard feed as rations; items such as rugs, boots and tack are used frequently and all of these things can pose additional challenges if you are caring for a horse with an allergy. However, with the right knowledge and management it is possible to make life easier and more enjoyable for both you and your horse.
Knowing what your horse is allergic to is the first step towards helping, so that you are able to look after your horse in a way that is specific to their individual needs. Once you know which mites or moulds might be the problem, you can implement strategies such as the ones discussed below.
The indoor allergens in your horse’s stable
Rugs and saddle cloths
Rugs and other textiles are a favourite place for mites to hang out and for moulds to grow. Washing items on really hot temperatures, and drying them in the sun when possible, will help as mites struggle in hot, dry conditions.
Try to change saddle cloths and rugs as often as is practical, and if you need to store textiles ensure they are dry before putting in air tight packaging.
Storage mites feed on grains and cereals and are commonly found in the dusty remnants at the bottom of feed bags. Placing the feed, in its bag, into resealable plastic containers can help prevent storage mites getting into the feed. You should clean these containers regularly, as well as rinsing your horse’s feed buckets daily.
Mould can also be a problem for incorrectly stored hard feed (where it is allowed to get damp) and also on fruit and vegetables or in poorer quality or badly stored forage.
We have probably all been guilty at some time or another of letting a few too many spider webs build up or allowing dust to settle on the ledges of our stables. These sorts of environments are a haven for dust mites who feed on the components of dust.
Keeping on top of cleaning your horse’s stable, as well as other areas such as indoor arenas and barns, will help to decrease the prevalence of dust mites.
Finding the best quality forage for your horse is not always an easy task, with availability varying year on year. However, ensuring you feed good quality hay or haylage, which is free from dust and mould could really help a horse who suffers with indoor allergies. Steaming or soaking hay before feeding can also be beneficial.
Dust can also easily build up in bedding, both in the stable and when it is being stored. Dust is thought to act as an irritant making the airways more susceptible to allergens. To reduce this, you could consider changing from straw to a dust-free alternative or even just rubber matting.
Mould will flourish on damp leather, especially on the spare bits of tack that you do not use as often. Try to keep tack and other leather items clean and dry. Prevent any general damp in your tack room by keeping it well ventilated and addressing damp patches in paintwork.
Mould is common in damp environments, such as behind peeling paint on brickwork or moist chipboard, or in water damaged buildings. Heavy vegetation, climbing plants and fallen leaves may also exacerbate damp issues so it’s a good idea to keep buildings clear of these.
Avoiding allergens is the most logical solution to prevent your horse reacting, however there will always be times where this is difficult whether that is due to the nature of the allergen, time pressures, cost, stabling facilities or your horse’s behaviour. Often additional measures need to be considered to help keep your horse symptom free.
There are different ways to treat allergies in horses and often a combination of therapies is the best approach.
Prednisolone and dexamethasone are types of steroids which are commonly used to ‘dampen down’ the immune response to an allergen. They are usually very effective in offering short-term relief from allergic symptoms. If used longer-term they can cause side-effects in some horses and they cannot be used under FEI rules. These can also be given locally (by inhaler for respiratory problems or a topical spray for itchy horses) which reduces the risk of side-effects.
Allergen-specific immunotherapy (ASIT)
Allergen-specific immunotherapy begins by helping identify which allergens the horse is reacting to; this can be done either by a blood test (serological testing) or a series of injections into the skin (intradermal testing). The allergens thought to be contributing to the symptoms seen can then be made into a bespoke, individual treatment, which is used to gradually to desensitise the horse to the suspected problem allergens. It takes a number of months for this therapy to become effective (and other treatments are often needed alongside, at least initially), however If the individual allergens have been identified, ASIT can be beneficial to around 60-80% of horses1, 2, 3.
Antihistamines and essential fatty acids
Certain types of antihistamine tablets may also be used and can be effective for some horses, although their effects are very variable. Supplementation with essential fatty acids has also been shown to be beneficial in some horses.
Shampoos and sprays can be used to help maintain healthy skin and support the skin barrier where needed. Some biting insects will not bite through layers of oil, so using certain products may help by providing a protective surface on the skin.
Whilst allergy is a lifelong condition, there is much we can do to help manage it. It is diagnosed through the exclusion of other common conditions that can cause the same symptoms. If you think your horse might be suffering from an allergy, we would always suggest you have a chat with your vet. They know you and your horse well and will be able to decide what the next steps should be in getting the right diagnosis and helping you manage your horse’s symptoms
- Yu, A.A. (2016). Equine Atopic Dermatitis – Management. In: Proceedings of the 8th World Congress of Veterinary Dermatology, Bordeaux, 2016.