Q: My 20-year-old Thoroughbred has respiratory allergies that require him to live outside most of the time. However, he’s a very easy keeper and needs to wear a grazing muzzle in the spring and summer. Is there anything I can do to help him breathe a little easier while wearing his muzzle? He sounds like he’s laboring.
—Shawna, Georgetown, KY
A: This is an interesting question and one that others may have to deal with. When we consider the kinds of respiratory “allergies” horses can develop, we commonly think about recurrent airway obstruction (RAO, or equine asthma or heaves). There are some geographic differences with regard to when and how horses demonstrate clinical signs of airway inflammation. However, regardless of the inciting trigger, horses with lower airway inflammation in the form of heaves generally demonstrate clinical signs of nostril flare, cough, and increased abdominal effort with expiration (exhaling). When horses are in remission from airway inflammation, they often appear to have a normal respiratory effort, but they could continue to have a mildly increased abdominal effort with expiration.
Triggers for horses to demonstrate clinical signs of airway inflammation include molds in hay, which in the northeastern/Mid-Atlantic region of the country may occur in the winter, when horses are housed primarily indoors and have hay and bedding material in close quarters. In the Midwest horses may be fed from round bales of hay that commonly contain mold spores. In contrast, horses in the southern/southeastern United States may demonstrate hypersensitivity reactions to pollens located on late-season pastures (summer pasture-associated RAO). Collectively, a number of triggers can cause a horse with airway hypersensitivity or equine asthma to demonstrate clinical signs of respiratory distress.
It is apparent you are an astute owner who is working hard to control exposure to triggers as well as overall caloric intake. Kudos to you for taking such great and comprehensive care of your horse throughout the year!
Because I am not familiar with your horse, I would ask that you consider a few things that could be contributing to him making a respiratory noise when wearing a grazing muzzle. First, have a veterinarian examine your horse to diagnose equine asthma. Based on his or her assessment, your veterinarian can prescribe medications that can quiet airway inflammation contributing to airway obstruction and the generation of airway noise, particularly when he wears a grazing muzzle.
Mature horses with heaves require intermittent medication at times of exacerbation to help resolve airway inflammation. Heaves is a lifelong condition, and although we can treat the symptoms we cannot cure horses of the disease. You might need to avoid using the muzzle at these times. Once you manage the inflammation and airway function is near or at normal levels, your horse may be able to resume wearing the grazing muzzle.
Additionally, it is important to determine that the muzzle fits your horse properly, to assure that it is not obstructing the air flow through his nostrils.
Again, I think it’s most important to have a veterinarian examine your horse, determine if lower airway inflammation requires further therapy, and proceed based on the diagnostic findings.
Elizabeth Davis, DVM, phD, Dipl. ACVIM
Professor and Section Head, Equine Medicine & Surgery,
Kansas State University College of Veterinary Medicine
A. Like Dr. Davis, I recommend first working with your veterinarian if you believe your horse has labored breathing while wearing a muzzle. If you can confirm the labored breathing is from the design of the grazing muzzle and not the allergies, then you could investigate different muzzle designs. For example, the Easy Breathe Grazing Muzzle has two openings in the material that correspond with the horse’s nostrils. This type of design in theory allows the horse to breathe easier. If you can find a muzzle design that works for your horse, we know from research conducted at the University of Minnesota that grazing muzzles reduce horse pasture intake by 30%. This reduction should help mitigate body weight gain in your easy-keeping horse.
Krishona Martinson, MS, PhD
Associate Professor and Extension Program Leader,
University of Minnesota, Department of Animal Science.