No, that’s not a misprint. “Heaves” in horses refers not to weight, but to chronic breathing issues found most commonly in older horses. It is a condition similar to asthma in humans. And, like asthma, it’s a lifelong problem that requires ongoing management to prevent its worsening and to maintain a good quality of life. At Penn Vet’s New Bolton Center, the Section of Medicine offers advice on this challenging problem.
How does an owner know his/her horse is developing ‘heaves’? Are there pre-disposing conditions that trigger the syndrome? And what can be done to minimize an animal’s susceptibility or symptoms?
A classic indicator for heaves is a persistent, chronic cough. It may be slight, such as three or four coughs at the beginning of exercise, but then it progresses to repeated episodes marked by difficulty breathing, wheezing, and nasal discharge. In its advanced stages, the horse will develop “heave lines” – a pronounced line along the lower half of the animal’s barrel, below its rib cage.
Because the horse breathes only through its nostrils, and not its mouth, managing respiratory conditions is vital, particularly for sport horses. And it is the routinely stabled and hay-fed horse that is most likely to develop the problem. Another contributing factor is closely confined travel in poorly ventilated trailers, so competition horses are also at risk, though it is generally understood that there may be a genetic pre-disposition to heaves among some horses and that not all animals will develop the condition.
Heaves, properly known as Recurrent Airway Obstruction (RAO), is caused by a hypersensitivity to inhaled triggers, usually hay and barn dust, or in the case of travel, fumes and particulates from car and truck exhausts. These triggers cause bronchoconstriction (airway narrowing in the lung) and accumulation of pus and mucus in the horse’s airways. A horse with heaves will have difficulty breathing at rest, and in advanced cases, its efforts to breathe using abdominal muscles will lead to the development of “heave lines.”
The condition, if detected early, can be managed by reducing exposure to triggers. This includes 24/7 turn-out, if possible, and a change of bedding material (if stabling is necessary) from straw to shavings or cardboard/paper. Barns should be very well ventilated. Horses can stand much greater degrees of cold than humans, so open windows and doors during cold weather isn’t really a problem for them.
If stabled, feed the “heave-y” horse dust-free forage, such as soaked hay or Dengie®. If signs of airway disease persist, the addition of either inhaled corticosteroids (“puffers” such as Flovent®) or oral steroids such as prednisolone or dexamethasone will reduce the inflammation in the lungs and resolve the signs in most affected horses. Sometimes a bronchodilator such as clenbuterol (Ventipulmin®) is used in conjunction with steroids, but recent research at New Bolton Center has demonstrated that, if used alone, it loses its effect after 14 days.
“Heaves” can’t be cured, but it can be managed, so the sooner the horse is diagnosed and significant environmental changes are made, the more likely it is that a working partnership may continue.