Q: Lately my gelding has started coughing when I first take him out of his stall and start warming up. He is kept in his stall about 12 hours every day. The barn he stays in is very open and has excellent ventilation. Is it possible that his hay is too dusty or is there something else that could be causing this?
Smartpak
two horses
horses eating hay
Does this recent Ask the Vet question sound like your horse? Maybe yours also has a bit of a snotty nose or you’ve begun noticing that he gets “winded” easier, that is, the same workout you’ve always done has become harder for him to both handle and to recover from. Read on to see how this particular question was answered, then learn what’s new in the realm of equine respiratory medicine (there’s a lot!)
A. Yes, it is possible that your horse is reacting to the dust, mold, or other irritants he’s breathing in with his hay or in the barn, even though the hay may be of high quality and the barn has excellent ventilation. I strongly urge you to contact your veterinarian and have him or her examine your horse as well as take a detailed history from you and perform a thorough walk through the barn to get to the bottom of this so that the correct management changes and treatment protocol can be started as quickly as possible. Whether the problem is allergies, infection, or some other disorder, your vet is the best resource to uncover the primary issue and get you started on the path forward!
The condition that comes to mind as I read your question is—and what you’ll want to discuss with your vet–Inflammatory Airway Disease, or IAD, which occurs in young to middle-aged horses. A related condition in middle-aged to older horses but not necessarily a progression of IAD is the more severe recurrent airway obstruction or RAO, sometimes referred to as “heaves.”
According to Dr. Melissa Mazan from Tufts University, IAD is a disease of young, athletic horses characterized by low-grade inflammation, low-grade airway obstruction, and airway hyper-responsiveness. Owners notice an intermittent cough, nasal discharge, and mild exercise intolerance. IAD is best diagnosed by looking at fluid obtained from the lower airways and best managed by controlling the environment, with medication sometimes also being helpful.
While you’re scheduling your vet appointment, take as many of these steps as you can to improve your horse’s “breathing zone,” which is the two-foot sphere around your horse’s nose from where he draws his breath:
• Soak or steam his hay.• Provide forage as chopped hay, cubes, pellets or in the form of a complete feed.• Feed from a container on the ground so any airway mucus drains.• Turn out as much as possible.• Use only dust-free bedding such as paper, cardboard, or corn cobs, not straw.• Provide as much ventilation as possible when the horse must be stalled.• Do not sweep or clean the barn or aisle when the horse is inside.
I know that my own horse, also diagnosed with this condition, is very quick to react to any hay in the trailer when I transport him. Therefore, any hay that is going along on the trip gets tossed in the bed of my truck (not in the feed bin of the trailer) and instead, he munches on soaked beet pulp and alfalfa pellets during the ride. Otherwise, I unload a coughing horse with mucus draining out of both nostrils who isn’t fit for a show, lesson, or even trail ride.
This response was written early in 2016, and since then, a panel of equine respiratory experts within the American College of Veterinary Internal Medicine (ACVIM) has released an updated “white paper” using the most current evidence-based medicine:
Couteil LL, Cardwell JM, Gerpter, V, et al. Inflammatory airway disease in horses – revised consensus statement. J Vet Intern Med 2016:30:503-15.
http://onlinelibrary.wiley.com/doi/10.1111/jvim.13824/abstract
The consensus statement is available online for anyone to read and I encourage those coping with horses suffering from airway disease to study it and to have a chat with their vet about the new terminology, clinical signs, causes, diagnosis, treatment, and management and prevention strategies. Here are a few of the highlights from the paper:
Terminology
“Recurrent airway obstruction (heaves) and IAD represent a spectrum of chronic inflammatory disease of the airways in horses resembling human asthma in many respects. Therefore the panel chose to use the term ‘Equine Asthma Syndrome’ . . .”
Clinical signs
The consensus statement includes an excellent table that differentiates IAD (mild to moderate equine asthma) from RAO (severe equine asthma). What separates them most is that horses with RAO have increased respiratory efforts at rest while horses with IAD do not. In addition, IAD often improves but RAO cannot be cured, only controlled.
Causes
In the past, chronic inflammatory airway disorders have been linked to allergies. But the consensus statement makes it clear that, while the true cause is still not completely defined, exposure to high levels of airborne particles and gases— over time— is central to the development of inflammatory airway disease. Examples of such particles include fungi, molds, endotoxin, ultrafine particles, microorganisms, mite debris, vegetative material, inorganic dust, and noxious gases.
Diagnosis
Ruling in IAD or RAO is as important as ruling out other causes of airway disease such as viral or bacterial infection, parasites, EIPH or “bleeders,” cancer, upper airway conditions such as laryngeal hemiplegia or “roaring,” and others. The gold standard of IAD diagnosis is a bronchoalveolar lavage (BAL). Also known as a “lung wash,” in this procedure the vet will insert a tube into the horse’s lower airways, squirt in some sterile saline then immediately draw it out, and examine the retrieved fluid for the type and amount of white blood cells obtained.
Treatment
The two most commonly prescribed medications for treating chronic inflammatory airway disorders in horses are corticosteroids and bronchodilators, and while they can be quite effective at controlling signs as well as progression of disease, neither is without risk. And it is noted that without also making changes in the way the horse is housed and fed, pharmaceuticals may be limited in their effectiveness.
In perhaps the most exciting finding shared in the consensus statement, recent studies demonstrated the value of two non-pharmacologic agents. First, supplementing the diet with omega 3 fatty acids, in particular DHA at 1.5 grams/day for 2 months, in addition to switching horses to a low-dust diet, was shown to provide more rapid improvement in clinical signs of IAD and RAO when compared to only low-dust diet. Clinical improvement was also greater in horses receiving DHA supplementation, with coughing being resolved in all of them by the sixth week of treatment! Second, the effects of inhaling a modified curcumin derivative found that it decreased white blood cells in the BAL fluid.
Management and Prevention Strategies
The most important step to take in decreasing a horse’s exposure to environmental contaminants is ensuring that what he eats and where he sleeps and stands is low-dust/low irritant. A paper from 2014 out of Purdue University concluded that feeding hay from a net resulted in significantly higher proportions of a certain type of white blood cell in the BAL than feeding hay from the ground. However, I would argue that here is where common sense needs to step in. After speaking with the primary author of the paper for more details, we learned that these were stabled racehorses fed from raised nets with normal-sized holes. In my opinion, horses turned out with small-hole hay nets, bags, or feeders positioned to allow a horse to feed in a lowered-head position should be healthier than those fed loose hay or hay in piles, as not only could mucus drain but also the horse’s nose would not be “buried” in the forage. And, personally, I’ve found that soaking hay is easier when it’s already in a hay net!
As should be clear now, chronic inflammatory airway disorders in horses are a complex, ever-changing concern. Fortunately, research is ongoing in this field, and horse owners and barn managers have an equally critical role in managing the respiratory health of horses.
Lydia F. Gray, DVM, MA SmartPak Staff Veterinarian and Medical Director Dr. Lydia Gray has earned a Bachelor of Science in agriculture, a Doctor of Veterinary Medicine (DVM), and a Master of Arts focusing on interpersonal and organizational communication. After “retiring” from private practice, she put her experience and education to work as the American Association of Equine Practitioner’s first-ever Director of Owner Education. Dr. Gray continues to provide health and nutrition information to horse owners through her position at SmartPak, through publication in more than a dozen general and trade publications, and through presentations around the country. She is the very proud owner of a Trakehner named Newman that she actively competes with in dressage and combined driving[ww1] .
[ww1]Final sentence was cut off so I deleted it.