Respiratory problems in horses can be very worrying for horse owners. After the initial disease/condition has been dealt with, symptoms persist and the horse may become more sensitive to future stimulants.
With assistance from the experts at HorseHage, this article provides information on the causes of respiratory conditions, including tips on best practice to reduce risk to your horse. This article does not cover respiratory diseases in detail; where possible, we have linked to useful resources for more information.
Respiratory diseases in horses can be caused by the following:
- Viral infection
- Bacterial infection
- Hypersensitivities
Viral or bacterial infection
Viral infections can include strangles, influenza, and equine herpesvirus, all of which are highly contagious and of serious concern to equine health. Immediate isolation of the horse should be arranged, and a vet should be called for testing to identify the infection type.
If a horse is suffering from a viral or bacterial infection, this can cause significant respiratory problems and discomfort. More often than not, symptoms will be significant, and treatment will be needed.
Following recovery, not all viral or bacterial infections will result in the horse becoming sensitized. However, research suggests that horses are more sensitive to respiratory allergens following an infection of the respiratory tract. The damage to the airways caused by the infection allows easier access of airborne allergens to the sensitive tissues.
The recovery period for any horse suffering from a respiratory disease will be prolonged in the presence of environmental contaminants.
Hypersensitivities
Allergic responses to inhaled fungal; or actinomycete spores; or noxious gases such as ammonia can cause respiratory problems. Symptoms may include inflammation of the small airways, increased mucus production, and bronchospasm. Issues such as a ‘dusty’ environment can exacerbate the pre-existing condition.
Examples of hypersensitivities include equine asthma or inflammatory airways airway disease (IAD), and Chronic Obstructive Pulmonary Disease (COPD). A horse with hypersensitivities will not be contagious to other equines and will not need to be isolated.
Hypersensitivity can occur over a period of years of exposure to environmental pollutants and will remain so for life. However, contributing factors to sensitivity will become less significant due to continued exposure.
What Cause Respiratory Problems In Horses?
Once the horse has recovered from a viral or bacterial infection, or he/she typically suffers due to hypersensitivities, the major allergens that can contribute and cause respiratory symptoms include fungal and other respiratory spores, especially the thermophilic actinomycetes; and ammonia and other noxious gases.
Hay is probably the most common source of fungal spores, most commonly caused by baling at too high a moisture content. A horse eating mouldy hay or stabled on a contaminated bed may inhale millions of spores with every breath. More importantly, significant levels of fungal contamination may be seen in hay which looks and smells ‘clean’, which means the challenge to the respiratory system can be greater for horses that are fed hay. Even when hay is soaked before feeding, some spores are still ingested along with any toxins that may be present, and as the wet hay falls to the floor and dries, the spores become airborne once again and are inhaled by the horse as well as contaminating the bedding.
Bedding should also be looked at as even the cleanest of straw will contain more fungal spores than alternative beddings such as wood shavings, paper or hemp. Deep litter beds should be avoided with horses that have respiratory problems as significant moulding can occur, in addition to the build-up of ammonia and the larvae of gastrointestinal parasites.
Ammonia released from a deep litter bed or poorly managed bedding where damp patches are left can seriously damage the horse’s airways and reduce the efficiency with which the horse copes with other respiratory allergens such as fungal spores.
Tips For Respiratory Management
Bedding – Straw bedding and deep litter should be replaced with a dust-free option such as shavings, paper or hemp, but will still require good management to avoid releasing ammonia into the horse’s environment.
Dust free forage – Choosing a dust-free forage may seem easier than it sounds. Often, the quality is only seen on arrival, and unless you flag it up with the provider, it’s difficult to address as you start to make your way through the bale(s). Using the same (good quality) hay provider can minimise the risk of receiving bad bales. Bagged forage/semi-wilted forage such as HorseHage in place of the hay ration can make a considerable contribution to reducing the respiratory challenge to all stabled horses and ponies. Alternatively, using a hay steamer may be beneficial.
Stable design – A well-designed stable which allows good ventilation without draughts should be sought in any case but is particularly important for horses with respiratory problems. An extra rug is preferable to closing the top stable door in cold weather.
Hygiene – A clean stable will help remove excessive dust and mould spores, dirt and cobwebs and ammonia. Brushing down ceiling trusses, sideboards, corners, and other fixed stable equipment will help with air quality. Remove the dirt as you go. Washing down with stable cleaners is recommended, especially where horses produce a lot of urine when stabled. Cobwebs and dirt easily build up; by removing these, you improve the horse’s living conditions. This should be done regularly for ease of management and to reduce the risk to the horse.
Tips for surrounding the stable
Muck heap – Don’t situate your hay store/barn or muck heap next to your stable or the pollutants will carry past the stable door.
Storage – Always feed high-quality, dust-free feeds and never use any feed that has gone mouldy. Store feed securely in a bin where it cannot get damp or be accessed by loose horses or rodents.
Hay – don’t be tempted to feed hay left on the barn floor.
In severely affected horses and ponies, medication may be necessary to control respiratory disease, so veterinary advice should be sought in this instance.
The importance of antioxidants in lung health has also been highlighted. Horses suffering from RAO (Recurrent Airway Obstruction) may have disturbed oxidant-antioxidant equilibrium and there are special antioxidant supplements on the market aimed specifically at horses suffering with RAO.
