Coughing and Wheezy Horses
Johnny Atkins BVSc
Vet Services Dannevirke
The classic ‘coughing horse’ is a common sight and sound at this time of year, and often transient viral respiratory disease is to blame. But as much as we love to blame a virus, they are not always the cause!
This year has seen an influx of allergy associated disease in all classes of stock and pets alike, and the coughing horse is no different.
‘Recurrent airway obstruction’ (RAO) is an allergy/hypersensitivity based disease of the lower respiratory tract. Most often described as ‘equine asthma’ or ‘heaves’, clinical signs vary from a mild cough at exercise, through to exercise intolerance, an obvious ‘wheeze’ and respiratory difficulty. In severe cases the expiratory phase (breathing out) will be split into two phases with an abdominal effort included. The abdominal muscles that assist breathing will become larger and form what is called a ‘heave line’ (see picture).
Most evidence suggests that the disease is due to the lungs’ hypersensitivity to inhaled allergens such as fungal spores, mould, dust and endotoxins. The most common form is seen when horses are stabled and fed hay, both of these practices resulting in increased exposure to potential allergens. However we do see a ‘summer pasture associated’ type of disease as well.
Subsequent inflammation in the lungs causes changes to the lung lining and constriction of the airways. In severe and chronic (long term) cases this can also result in airway thickening and significant lung changes, all of which tend to further exacerbate the disease.
Diagnosis is often based on history, clinical signs and response to treatment. In small ponies and miniatures, radiology may be useful as a diagnostic aid and in others endoscopy (scoping) and lung function testing can be performed as well. The ideal method for diagnosis involves flushing fluid into the lungs and collecting it again in a process called ‘bronchoalveolar lavage’. Analysis of the cell types found in the fluid will give a diagnosis. Generally infection is not present, however due to the lungs’ reduced ability to defend against pathogens, it is possible that some horses may develop a secondary pneumonia which can further complicate the disease.
Treatment of mild cases often respond well to management and dietary changes, including turn out, low dust bedding, change of hay or soaking before feeding. Pasture turn out is often crucial to management of these cases! In more severe cases, change of management should be combined with treatment with bronchodilators (to dilate airways) and steroids (to decrease inflammation). This can initially be in the form of oral treatments, but inhaler therapy is recommended long term. This provides targeted drug concentrations in the lungs with minimal side effects through the body. Putting your horse on an inhaler for its asthma sounds a bit weird, but with some investment in the correct equipment it is a simple, cheap and effective long term treatment protocol!
Due to its allergic/hypersensitive cause, RAO is a lifelong disease and will require long term management and treatment. That being said, early identification of the issue and relevant risk factors make it very controllable, and most horses when managed correctly can live long wheeze-free lives!
Read more >Thursday 7th of March 2019: Stomach ulcers (gastric ulcers) are a hot topic! Stomach ulceration is a somewhat confusing syndrome âÇô the syndrome can have a multitude of clinical signs, ranging from very subtle performance issues, or picky eating, to weight loss and colic. There is also a multitude of products on the market which claim to help with ulcers, not all being equal.
Read more >Thursday 7th of March 2019: âÇśSmall StrongylesâÇÖ or âÇśCyathostomesâÇÖ are the terms used for a group of over forty different species of parasites affecting horses. They tend to be the most prevalent parasite within the horsesâÇÖ gastrointestinal tract and although small, heavy burdens can result in big problems!
Read more >Friday 27th of July 2018:
Read more >Friday 27th of July 2018: With the equestrian season kicking off in most disciplines, Spring is a good time for your horse to have its annual âÇťwarrant of fitnessâÇŁ.
Read more >Wednesday 25th of July 2018: We have had a couple of interesting cases over the last few months where our Vets have been able to use the endoscope to help diagnose and address issues.
The endoscope is a flexible camera/video /light source that we can use to help investigate respiratory tract in horses as they allow us to gain access visually to some of the nooks and crannyâÇÖs that make up a horses upper and lower respiratory tract.
Read more >Thursday 8th of March 2018: The transportation of horse to events in NZ [such as HOY] is commonplace but in saying that it needs to be managed to maximise athletic performance, and minimise the risk of any negative impact on horse health. After all it is a long expensive and disappointing trip to an event to have your horse perform below their best.
Road transport can be detrimental to horse's lungs, muscles, gut function and weight
Read more >Thursday 8th of March 2018: Alfie is a 22 year old Kaimanawa gelding who had the misfortune of getting the wrong end of a stick during a wind-storm.
He presented with acute right eye pain âÇô eyelids tightly closed with profuse tearing.
Read more >Thursday 27th of July 2017: The first five years of a horse's life are critical in regards to dental development. Like us, horses have two sets of teeth, the deciduous being shed from about two and a half years until the permanent teeth have erupted at around five years.
Read more >Thursday 27th of July 2017: Some horse owners are still drenching their animals on a six to eight weekly basis regardless of age or worm burden. This was a traditional approach which is outdated and possibly detrimental in terms of developing resistance to drenches.
Read more >Friday 1st of April 2016: With the current surge in interest in equine dentistry, more than a few myths have crept into popular belief. Find out more.
Read more >Friday 1st of April 2016: Spring and early summer are the high risk periods for pasture - induced laminitis, so this is a timely reminder of what this disease is and how you can avoid it.