As we are coming into the time of year when more of our horses are stabled and/or supplemented with hay, it is common to see an increase in the number of horses who cough.
Coughing may seem like a trivial subject especially as the odd cough really isn’t anything to worry about, but for those owners whose horses are coughing so much it is affecting their ridden work, or if they get regular coughs due to allergies it can be incredibly frustrating.
Why do our horses cough?
There can be multiple causes, but horses usually cough for one of two reasons:
- An infective process, for example a viral or bacterial infection.
- A non-infective cause such as an inflammatory condition.
In this article we will be looking at inflammatory conditions.
Making that distinction between the infective and non-infective is really important as it impacts both the treatment and the management plans, as well as being influential to the recovery and prognosis.
The terms we use around inflammatory airway conditions have changed a lot over the years which can be confusing, but we do still hear older terminology.
We would quite often hear about Heaves or Inflammatory Airways Disease (IAD), then we have Recurrent Airway Obstruction (RAO), Chronic Obstructive Pulmonary Disorder (COPD) – which is the same as RAO, and also Summer Pasture Associated Recurrent Airway Obstruction.
There is so much we have to consider when we talk about inflammatory airway disease but in recent years, it has been simplified with Medicine experts agreeing that all the conditions sit under the name Equine Asthma Syndrome.
This makes it a bit easier for owners to understand as it is relatable to a human condition!
What causes a horse to cough?
The airways are responding to a challenge they are exposed to, mostly an environmental challenge.
- Fungal spores, dust spores, pollen particles, ammonia in their stable, and then to any micro organisms they are exposed to – bacteria, viruses and fungal spores.
These will challenge the respiratory system, usually into some kind of inflammatory reaction. In horses most of their cough receptors are right down in the lungs, in the thin walled lower airways. Those airways are going to respond to the airborne challenges, usually with some kind of inflammatory cell reaction. They will increase the respiratory mucus that is produced so there will be an increase in volume of the mucus as well as an increase in its thickening. That results in an inflammation and a narrowing of those lower airways. The cough receptors are stimulated, normally because those airway walls are touching each other, then the cough reflex is triggered.
This is different to humans as most of our cough receptors are up in our laryngeal area, so we are triggered to cough more frequently by more upper respiratory problems.
Diagnosis
The symptoms can range from very mild to severe and sometimes the conditions are difficult to diagnose with just a clinical examination alone.
This is because there isn’t a strong correlation between the changes your vet might hear in lung sounds or breathing pattern with a specific diagnosis. Your vet might need to use diagnostic tests quite early on in the course of a respiratory condition to get the answers they need.
Inflammatory conditions are under diagnosed because the conditions in most of the horse population don’t affect their tolerance to exercise. They go un-noted because they are only affecting the horse at extreme levels of exercise.
Even if they are only coughing at rest or in light work, or there is only a bit of mucus outside their stable in the morning, it is still important to have a chat with your vets to see if you can make any environmental changes to begin with.
The best ways of diagnosing the reasons for coughing are –
- A tracheal wash which is done with an endoscope down into the first part of the airways; through the larynx and down into the trachea.
- A Bronchio Alveolar Lavage (BAL) to retrieve the respiratory secretion samples in the lower airways.
It’s important that both of those tests are used in the right way and the results interpreted correctly.
If you consider when you go to the doctors thinking you have a chest infection, and the conversation is about understanding more to determine if it is viral versus an actual chest infection, and whether antibiotics are actually needed.
We can often feel really rough with a horrible cough, but we don’t actually have an infection and don’t need antibiotics to treat that. It is so important to get the right treatment options and rehabilitation strategies in place through the diagnostics.
What treatments are available?
The mainstay treatments for most inflammatory airway conditions are steroids – potent anti-inflammatories, and a subset of drugs which are called the Broncho Dilators which in simple terms widen the lower airways.
The idea of these treatments is to take away the inflammation which means the lower airway walls are thinner, they’re less likely to touch each other and stimulate the cough receptors.
The Broncho Dilators dilate the lower airways so the walls are further apart, so again the cough receptors are not stimulated.
They are both systemic meaning they go in their feed, but they are not a long-term solution. There is an increased risk of laminitis for horses on steroids, so you have to be careful which horses are prescribed them.
There are some equine inhalers which you can fit right around the muzzle of horse and then fit the same inhalers as a human has onto that system so the horse can breathe them in – although this method comes with its challenges and is only suitable for certain horses.
The last way of getting the drugs in, is a nebulising treatment which can be quite expensive, and again the horse has to tolerate having the nebuliser on.
It is important to note that antibiotics are rarely used as a treatment option, it is important to get the correct diagnosis and treatment usually involves the use of Ventipulmin or Diatoral and the steroids.
Rest is really important for horses who have got an issue. Respiratory tissues are just like any bodily tissue. If you had an inflamed muscle, you would rest it until that inflammation had gone away, if you exercise an inflamed respiratory tissue you will exacerbate that inflammation.
No forced exercise has to be the rule!
That doesn’t mean box rest. The rest period will be different case by case. It might be for a short time for a mild case, or a longer time for more severe condition.
Is my environment dusty?
When you blow your nose after you have been to the stables, you know if you have been in a dusty environment, so it is worth considering that your horse will have been breathing the same in all day.
If you tissue is dirty then consider if you could improve your own horse’s environment and how you manage them.
Management tips
As owners it is important to regularly assess your horse’s environment even if they don’t have Inflammatory Airway Disease. We should be trying to keep their environmental challenges as low as possible:
- Feeding hay from the ground, not from a net. Studies have shown that from a net there is 4x the particle exposure compared to eating off the ground, whether you have a dusty stable floor or not, it is the haynet that seems to be the issue. If you have a horse with an inflammatory airway issue not feeding from a haynet is advisable.
- Soaking hay or feeding haylage or baked products can reduce the particle exposure to the airways by about 60%.
- Sprinkle walkways with water before sweeping them so that you aren’t generating dust.
- Avoid storing hay over head in stables if possible. If it isn’t possible, make sure you have the hay covered so you don’t have dust falling down onto the horses.
- Remove horses from stables while they are mucked out or any sweeping is being done.
- Avoid using blowers to clean internal walkways.
- Removing cobwebs and anything that collects dust routinely when the horses are not in the stables.
- Improve ventilation. If horses that are suffering from IAD are kept in a barn and don’t have stable windows, try to keep them in a stable closest to the door so they have fresh air coming through.
- Get them outside as much as possible will usually help – except for those horses that are affected by the Summer Pasture problem.
- Change from straw if it is dusty, to other bedding, although it is worth noting not all bedding products are dust free. Find a product that works for you.
Supplements
Not all supplements do what they claim – but if you would like to add a respiratory supplement then do your research to select one that has been scientifically tested by an independent trial. It is always worth asking your vet for advice.
Most vets will happily offer advice. If you notice a cough and/or nasal discharge then ask your vet for advice as often conditions which are treated quickly have a much better prognosis.
Thank you to Loch Leven Equine Practice for their help with this article
