WHAT IS EQUINE ASTHMA?

Until recently, anyone with a chronically coughing horse would have probably heard their vets use terms like IAD (inflammatory airway disease), COPD (chronic obstructive pulmonary disease) or RAO (recurrent airway obstruction) and if they searched the internet after the vet drove away they would have come across people talking about their horses having ‘heaves’ or ‘broken wind’. So which disease does your horse have? It can all be very confusing.

These days we call all of these conditions - Equine Asthma. Want to know more? Read on.

Most equine asthma is caused by a hypersensitivity to inhaled dusts, moulds and toxins commonly found on straw and hay.

Equine asthma occurs in almost every country in the world and occurs mostly in horses between 9-12 years of age but is seen in older horses too. Stabled horses are most commonly affected in the winter and spring as that is the time when we bring our horses into stables and feed them hay and bed them down on straw.

Because IAD, COPD and RAO are now all called equine asthma, a horse with asthma could show many slightly different symptoms. The main problem owners report is that their horse is coughing. This may be an occasional cough when worked or almost constantly with the horse having coughing fits and looking very unhappy. The horse may develop a heave line which is a line along either side of the horse’s belly as it struggles to get air in and out. If the asthma is severe enough the horse may develop a nasal discharge and you might find the horse is coughing up foamy white discharge which can collect just outside the horses stable as the horse looks out over their door. Sometimes though, all you may notice is that the horse just isn’t ‘keen to go’ and seems lethargic or easily ‘puffed out’ after a small amount of exercise.

So how do we diagnose equine asthma? A good history followed by a thorough clinical exam can go a long way to making a diagnosis but the best way is by using an endoscope, which is a flexible camera that allows your vet to visualise your horse’s upper airway and take a sample from the windpipe if required. The test is well tolerated and with right equipment can be all over in about 15-20 minutes.

Another useful test is taking a sample of the cells from a small part of the lung. This is done using a long tube that allows the vet to wash out a portion of lung itself. The results are thought to be more accurate than other tests but can sometimes be harder to do and in my experience does make the horse cough. We use local anaesthetic to numb the windpipe but horses do still cough.

If your horse also has a nasal discharge as well as a cough, don’t be surprised if your vet takes samples for infectious diseases such as equine influenza virus, equine herpes virus or even strangles as all of these diseases can look the same as equine asthma.

For horses that have equine asthma, lifelong environmental and dietary management is a critical part of treatment. By reducing a horse’s exposure to dusts and mould we can drastically improve the horse’s lung health. Sometimes we use medications that reduce the horse’s response to dusts and / or use products that open the horse’s airways so allowing it to breathe more freely. The important thing to remember is that equine asthma cannot be cured and the horse will always have a problem if exposed to hay and straw. Thankfully the prognosis for equine asthma is often good for horses and with the correct medications and management, the horse should be able to continue most riding disciplines. The important thing is to make a prompt diagnosis and rapidly implement treatment, as not treating a horse with equine asthma can eventually lead to permanent lung damage.