My 12-year-old 16hh mare has just started coughing. The cough is deep and rough. She coughs two or three times and then only occasionally thereafter. The same thing happened this time last year and the year before. Each time the vet prescribed ventipulmin and suggested a pollen allergy such as summer pasture associated obstructive pulmonary disease (SPAOPD). The cough usually clears up after the medication but returns the following year — why?

She is turned out 24/7. I had just started putting hay in the field, but it was extremely clean and I dampened it; she has picked at it for two or three weeks with no problems. She has no nasal discharge, is fit and healthy, had her vaccinations last month and eats well.

There has been harvesting around her field recently, but no other horses have been affected.

Could you give me advice on SPAOPD and anything I can do to stop her coughing next year?
CE

We spoke to vet Karen Coumbe, who explained that SPAOPD is a type of hypersensitivity of the lungs to inhaled pollens and moulds, and that the harvesting of crops in nearby fields is a common trigger for animals that suffer with it.

“The condition tends to occur between spring and early autumn, with complete remission during the winter. Once the horse is affected, the signs tend to recur in subsequent years, and incidences increase with age,” explains Karen.

“Signs are often worse when conditions are hot and dusty. Once the airways become hyper-responsive, non-specific triggers such as cold or dry air, irritant dust and exercise may exacerbate the problem.”

Clinical signs include:

• severe respiratory distress, coupled with fast, shallow breathing

• breathing out is particularly laboured, as the airways are obstructed

• there is a marked abdominal lift on expiration, as the muscles are used to help force air out of the lungs

• a “heave line” develops in the muscles on each side of the ventral abdomen

• coughing

• flared nostrils

• nasal discharge

“Mildly affected horses and ponies have a normal appetite and demeanour. If the condition is chronic and severe, the animal is likely to experience some weight loss, and, if left untreated, SPAOPD can be very debilitating.

“In addition to the administration of appropriate medication, it is recommended to remove the horse from the source of the inhaled allergens, where possible. Provided the horse does not also suffer from allergies to stable dust, it may improve if stabled in an environment that is as dust-free as possible.

“The problem is that horses that suffer from this condition also frequently have other airway problems and can suffer from a severe stable cough too, which makes it difficult to know how best to manage them to keep them comfortable.

“The addition of a balanced antioxidant supplement to the diet can improve respiratory function and reduce inflammation. However, the condition tends to recur in subsequent years and effective management is often very difficult.”

This Q&A was first published in Horse & Hound (5 October, ’06)