Small Airway Disease COPD

What is COPD?

It is small airway disease COPD of the lungs (the small tubes are the alveoli and bronchioles). Effectively it is an allergy to fungal spores and pollen that are inhaled that causes the airways to become inflamed, thickened and produce mucous. The muscle in the airways also constricts (bronchospasm) as in asthmatics. This pathology leads to a narrowing of the airways and means that your horse has difficulty breathing.

Clinical Signs

With COPD you will normally see one or a combination of the following; coughing, slight nasal discharge and abdominal breathing (you will often see a line along the abdomen and your horses flanks rapidly moving in and out). These signs often progress over time, initially you may just notice that your horse is not working very well then it may start to have the odd cough. Eventually your horse may cough and have a nasal discharge at rest and occasionally may even go into acute respiratory distress and struggle to breath.

The problem with respiratory disease is that the clinical signs only vary a little with different diseases; therefore, it may be difficult to distinguish between an infection and a respiratory allergy.

These symptoms are sometimes only seen at certain times of year especially when the cause is a specific type of pollen or fungus. They may also been seen more when your horse is stabled.

If the horse is exposed to dusty environments such as barns where straw or hay is stored or if the stable is near the muck-heap , there may be a worsening of the disease.

There is also a form of this problem known as Summer Pasture Associated Obstructive Pulmonary Disease (SPAOPD) that appears to be caused by exposure to pollen in the same way as exposure to fungal spores.

Diagnosis

Diagnosis of COPD is based on clinical signs and history along with endoscopy (this is when a camera is put up your horse’s nostril and into its lungs). We may also take samples for microscopic examination such as tracheal washes or broncho alveolar lavages (BAL).  These allow evaluation of the types of cells present in the lungs which vary in cases of infection and respiratory allergies.

Treatment

The best treatment is to remove the things that are causing the allergic reaction. There are many different types of bedding available such as paper, shavings or there are now special hypoallergenic materials available. If possible you should not stable your horse next to a horse on straw and away from the hay barn etc. Make sure you soak your hay properly before feeding it and put water on any dry feed you give. Ensure your stables are well ventilated so your horse gets lots of fresh air.

If necessary your vet may prescribe some drugs to help your horse breath more easily – these are NOT a substitution for good stable management. Clenbuterol (Ventipulmin) is commonly used this helps open the small airways and therefore the horse can breath more easily; bromhexine (sputolosin) may be combined with ventipulmin or used alone to help thin the mucous to allow the respiratory system to remove it.   Occasionally other medications are used some of which can be given by inhaler (just like when humans get asthma but a specialist horse inhaler and drugs are used).

The inhaler we use for these is a specialised “Equihaler” that is a rugby-ball shaped mask that fits over one nostril and allows direct medication of the respiratory system.

Corticosteroids are a very effective drug at controlling these types of disease although there is a risk of laminitis with long-term use. Care must also be taken with small ponies!

Allergy ELISA tests and desensitisation injections can be used once the types of allergens have been identified.

Your veterinary surgeon will recommend the appropriate treatment for each case.

REMEMBER GOOD STABLE MANAGEMENT AND GOOD VENTILATION IS THE KEY!

Obviously for SPAOPD it is very difficult to reduce exposure to pollen, although there are desensitisation injections that can be used following ELISA testing of the different types of allergens that potentially may cause these problems. Often steroids are the only alternative for this condition. This is also true for COPD.