I have a 10 year old 1/2 Percheron 1/2 Quarter Horse mare, and we live in the Midwest outside of Chicago. My mare suffers from severe seasonal allergies - she is the worst in spring/fall. She will cough, have a runny nose & eyes, sometimes has hives, and becomes a little lethargic. I keep her on Cough Free year round. I've tried Tri-Hist to no avail (she will not eat it, and I board, so force-feeding it 2x days is not feasible). Dex works great, but is not show legal - any suggestions on other supplements/medications I can try that are show legal? She does get all day turnout in grass pasture, is inside at night on shavings. She eats alfalfa mix hay and Safe-Choice pellets, along with her SmartPak which includes MVP 4-in-1, Cough Free, and Stress-Dex.

Shame on me for jumping to conclusions, but I’m going to assume from your description that your mare has been diagnosed with “heaves,” or, as it’s being called now, Recurrent Airway Obstruction (RAO). For years the scientific name of heaves was Chronic Obstructive Pulmonary Disease or, COPD, but the name was changed recently because COPD in humans is nonreversible and associated with smoking. RAO, on the other hand, IS reversible, and not generally caused by horses using cigarettes (horses have their vices, but smoking usually isn’t one of them!)

You’ve already mentioned some of the signs of RAO and I’d like to add to your list:

• Coughing (can be dry or productive)
• Labored breathing (can make a horse anxious and sweaty)
• Flared nostrils at rest
• Nasal discharge
• Depression and/or inappetance
• Elevated respiratory rate at rest
• Exercise intolerance or poor performance
• Increased movement of abdomen during breathing (causing the “heave line”)

Veterinarians are able to diagnose heaves without too much trouble using just the history owners give them, a physical examination and bloodwork. However, it’s important to rule out other diseases with similar signs, so specific tests may need to be performed, such as blood gas measurements, endoscopy, chest X-rays, bronchoalveolar lavage (BAL), lung biopsy and lung function testing. And having a baseline or beginning value can help determine if the horse is responding to treatment.

Unfortunately, there is no cure for RAO, but it can be successfully managed. Have you tried taking your mare off hay completely? Organic dust in hay is the main trigger for episodes of “heaves.” If this is not practical—or you can’t find a suitable alternative to replace the fiber in her diet—try soaking the hay for two hours before feeding it.

I’m glad to see that your mare spends at least some time outside on pasture. Is there any way she could be kept outside 24/7? The dust in barns from bedding, traffic in the aisles and even hay that other horses are eating nearby can also trigger episodes. If she must be stalled, avoid straw.

You mention that you have not had any success using antihistamines to treat your mare. This is fairly common. The two categories of medication that DO work are corticosteroids (for example dexamethasone) and bronchodilators (for example clenbuterol). These two drug classes work well together as corticosteroids relieve airway inflammation and bronchodilators relieve airway obstruction. However, they are to be used to treat episodes of RAO, tapering off as improvement is noticed and dietary and environmental management changes are instituted. They are not to be used year-round or in place of removing hay or keeping the horse outside. Ask your veterinarian if the combination of corticosteroids and bronchodilators might be right for your horse, and if giving them through a special equine inhaler would be helpful.

From speaking to other horse owners struggling with RAO, it seems as if the over-the-counter supplements intended to help horses with heaves work in some but not in others. If Cough-Free works for your mare, that’s great! Other choices are plant adaptogens, which restore the body’s natural equilibrium; botanical preparations combining the extracts of several medicinal herbs; and antioxidants, like Vitamin C especially, which may neutralize the oxidative stress associated with RAO.