Go Back

Asthma

What is asthma?

Asthma is an inflammatory disease affecting the lungs which is triggered by environmental factors including dust and pollen. It was historically known as COPD and RAO and can also be referred to as heaves or broken wind. It is not contagious and often life long to a degree requiring ongoing management to prevent flares.

Symptoms

There is a scale of symptoms which correlates with severity of disease fairly well.

Mild disease:

• No signs at rest, only signs when exercised
• A cough or a few coughs at the start of a ride particularly when go into trot but then nothing more once gets going
• A slight runny nose after exercise – clear or white

Moderate disease:

• Some mild signs at rest, worse signs when ridden
• Snotty nose at rest, usually found on the floor over the stable door in the morning. The snot can be thick white or creamy coloured
• Coughing occasionally at rest particularly after eating, coughing more consistently when ridden not just at the start
• Some reduced athletic performance or exercise intolerance such as seeming to tire quicker, clearing nose more, breathing heavier or having flared nostrils at exercise
• Heave line seen during or after exercise. This refers to a visible line at the back of the abdomen between the tummy muscles and becomes obvious because the horse is having to use these muscles more to breathe

Severe disease:

• Marked signs at rest
• Coughing frequently at rest particularly after eating
• Snotty nose frequently at rest – seen on stable floor and at nostrils. The snot is creamy or white or may be yellow or green if a secondary infection is present
• Heave line at rest
• Visible increased laboured breathing and flared nostrils at rest
• May appear dull or not right and not want to eat like normal
• Acute asthma attack – panting, visibly struggling to breathe, noisy breathing

If a horse demonstrates signs of severe disease and you suspect they may be experiencing an acute asthma attach an emergency vet visit is required.

Diagnosis

Asthma can be diagnosed or at least suspected based on clinical assessment alone sometimes. Ruling out an infection may be required via a blood test or nasal swab. Accurate definitive diagnosis requires a tracheal wash or bronchioalveolar lavage test done via endoscopy under sedation. The samples taken during the endoscopy are sent to a laboratory for analysis of the cells and high levels of particular inflammatory cells (neutrophils) in the absence of infection determines asthma.

Treatment

Initial stabilisation and treatment of the episode:

Steroids

the underlying driver of asthma is inflammation and so treating this is key and often requires steroids. This may be a one-off injection, a course of oral tablets and/or inhaled medications via a nebuliser, aservo inhaler or human inhalers via spacer.

Buscopan

Most commonly associated with colic this drug is useful in the emergency asthma attack scenario as it relaxes smooth muscle – whereas in colic this is useful to stop stomach spasms, in asthma it reduces bronchial spasms and relieves symptoms quickly. This is a one-off injection.

Ventipulmin

An airway opener relieving bronchial spasms which can be given orally in food for up to 2 weeks as a course of treatment.

Sputulosin

This breaks down mucus making it easier to cough up and clear the airway and may be indicated if your horse is producing a lot of mucus. It is a powder which goes in feed for a course of treatment.

Remove any obvious triggers

See management measures

Preventing Recurrence

Controlling the environmental triggers

See management measures.

If environmental control is not sufficiently preventing symptoms (i.e. flare ups happen frequently) then a low dose of ongoing medication may be required. This is most commonly done now using a nebuliser to deliver steroids, saline or ventipulmin directly to the lungs. The alternative is pulse therapy with oral or inhaled steroids and/or ventipulmin when the symptoms are worse.

Management Measures

Horses suffering from asthma are usually triggered by one of two things – dust or pollen. Generally, these will then either be seen in the winter or summer. Of course, horses can be sensitive to both and there can be some cross over but it is worth monitoring timing of any patterns to help pinpoint the trigger.

Dust and mould

The biggest source of dust is straw, next is hay, then soaked hay, then steamed hay and haylage. The first thing to address with an asthmatic horse is the stable environment. Firstly, if possible, these horses may do better living out 24/7 – there is no better airflow than being outside. If stabling is required, then optimal airflow needs to be considered – this can be as simple as opening windows and doors or making some if they don’t exist. A deep clean and de-cobweb is required and switching to a dust free bedding will play a big role. A huge trigger is the forage they eat, dry hay is likely to be a problem for an asthmatic horse and if you watch a horse eat you will see the spores released from hay as they eat it and inhale it immediately. Likewise keeping feeds soaked can reduce the physical irritation at the back of the throat which may trigger a cough. Haylage or steamed hay is optimal, soaked hay may be sufficient for a less severely affected horse. Regardless of the type of forage the quality and cleanliness of it is imperative and no mouldy forage should be fed to an asthmatic horse.

Pollen

This is trickier to manage as pollen is everywhere and you can’t prevent it. All you can do is reduce exposure and manage symptoms meaning that summer affected horses tend to be harder to manage. It may help to stable the horse (in a well-managed dust free stable) during high pollen times of the day, there are apps which are useful at helping to see when the pollen count is high to help guide this. Sometimes it can be clear which pollens trigger a horse more, for example earlier in the season tends to be tree pollens and some are particularly affected when nearby rapeseed is harvested. Learning these triggers can help you prevent recurrence the following year by being prepared – e.g. move to a field away from many trees or stable during the harvest. Other simple things which may help include using Vaseline around the nostrils to capture pollen reducing inhaled amounts and using a pollen specific nose net. Exercise will always increase the risk of an asthma attack so if you know your horse is pollen sensitive it may be sensible not to ride during these periods or peak times of the day. In some cases, systemic anti-histamines are helpful such as piriton 4mg tablets, although the dose rates are high with an average 500kg horse usually needing around 20 tablets twice a day to see some effect and this will work better in a preventative way opposed to once symptoms have started.

An area of interest in these cases is immunotherapy

Which is essentially vaccinating the horse against the allergens that he/she is allergic to. The immunotherapy we use via injections for allergic skin diseases in horses is thought to not be effective against asthma although some people try it. In the last few years there has been research into inhaled immunotherapy which shows some promise in asthma cases (in humans and horses) so this may play a role in treating these horses in the future.

Prognosis

Mostly asthmatic horses can be well managed and live with a good quality of life. However, it can be labour intensive and expensive as it is a condition that the horse will have for the rest of its life, and it may worsen with age. It may also have an impact on the athletic use of a horse during periods of time where the horse’s trigger is bad and if the horse is rendered exercise intolerant they cannot perform in their intended way. In some scenarios despite the most committed management and best treatments horses can become too severely affected or unresponsive to treatment and require euthanasia sadly. Thankfully this is the minority of cases and a worst-case scenario with most horses doing well.