Every Little Bit of Breath is Critical

Signs of respiratory challenge can be subtle, but recognizing and addressing them has significant performance payoffs.
by Kim F. Miller

Ninety seconds. That’s how long I last breathing only through my nose while at about 75% exertion on my morning treadmill run. At that point, I need a big gulp of air through the mouth to prevent passing out.

Horses can’t do that. They’re “obligate nasal breathers,” meaning they can only breathe through their nostrils. Also, unlike humans, they can’t take multiple breaths per step, because their inhalations and exhalations are linked to their canter stride.

These unique aspects of equine respiratory function are among several reasons respiratory health is so important to equine performance. Narrow upper-airway passages are another, along with the long trek oxygen makes from nostrils to lungs, where it’s transferred to the bloodstream and delivered to all cells in the body.

Muscles are greedy for oxygen, and horses’ bodies have a lot of muscle: about 60% of their body mass, compared to 33% to 39% for an average man. All of which explains why horses can become oxygen deficient at lower levels of exertion than people do.

Oxygen’s journey from the nose to the bloodstream involves complicated processes at many junctures, explains Dr. Catherine Kohn, who has served as United States Equestrian Team veterinarian and as FEI veterinary delegate at such events as the Atlanta Olympic Games and the Land Rover Kentucky Three-Day Event presented by MARS Equestrian™. Compromised function at any waypoint limits the horse’s ability to make use of whatever capacity that system has for oxygen.

“The horse’s capacity for acquiring oxygen and using it are not synonymous,” Dr. Kohn said. The bigger the horse, the bigger their lungs, but also the more demand for oxygen. Structural or functional issues and constriction caused by disease and inflammation can make any size advantage moot when it comes to using air supply.

A little bit of compromise can translate to a substantial decrease in performance. Many veterinarians consider respiratory challenges the biggest reason for poor performance in otherwise sound horses, and that’s often the case even when the symptoms are subtle —sometimes non-existent.

Subtle Symptoms

Watching for those symptoms and considering respiratory function even in their absence are key to protecting respiratory health. Preventing problems is ideal. Catching them early is second-best, because that’s usually when they can be addressed relatively easily, often through environmental changes. In the realm of non-infectious respiratory diseases, these are usually reversible conditions on the milder end of the equine asthma spectrum.

Although inflammatory airway disease affects an estimated 80%+ of the active sport horse population, it can appear “amazingly asymptomatic,” says Dr. Wren Burnley, a veterinarian and Grand Prix dressage rider based in Kentucky. “Whenever we scope a horse, we often have owners who think their horse doesn’t have inflammatory airway disease at all,” she said. “Yet we often find signs of it.”

Belgium-based sport horse vet Dr. Emmanuelle van Erck Westergren works primarily with elite athletes and has had observations similar to Burnley’s proven in recent research.

“We have tracked 400 cases in which horses were referred to our practice for poor performance,” Van Erck Westergren explained. “Between 50% and 80% had some degree of respiratory disease. Eventers had 100% and international show jumpers had 85% at the high end, while driving and leisure horses were at the low end with 50% affected.”

In a study published in 2019, Westergren and her team found that 88% of 731 horses referred for poor performance had inflammatory airway disease.

A Cough Is Concerning

An occasional cough that would be dismissed in a person is often a symptom of early respiratory disease in a horse. That is when most veterinarians would like to get a call to check it out. Nasal discharge is another symptom, along with an elevated at-rest respiration rate. (Ten to 14 breaths a minute is considered normal for an adult horse. This can vary, so it’s important to know your horse’s baseline.)

In the study van Erck Westergren references, most owners’ complaints “were very unspecific,” she explained. “‘Feeling heavy’ is a top complaint. Heavy breathing, breathlessness, lack of energy, and slow recovery times are more common complaints. Owners seldom noted coughing or nasal discharge, which are more clear symptoms of respiratory problems.”

Four-time Olympic jumping medalist Beezie Madden recalls a horse who presented no symptoms in the barn but became “heavier in the bridle toward the end of the course. He normally had a very nice mouth, but he’d get heavier as the course went on. It was described to me that he could get more air if he had his head down.” An endoscopic exam confirmed respiratory issues.

Unusual fatigue in an otherwise fit horse could be another warning sign that won’t show up in the barn behavior, Madden suggests. Tension also can be a sign. “If a horse can’t breathe well, they are going to get tense,” Madden said.

U.S.-based Irish jumping rider Nicky Galligan has exercise-induced asthma. Early in his Grand Prix mare’s ascent, he recognized Javas Miss Jordan seeming to feel the way he had before he was sidelined on the soccer pitch needing inhaler treatments.

“It felt like she was a little out of breath,” he explained. “I could relate to that. I’d always felt that the occasional rails were never the result of her being uncareful or unfit, but of her having the moment of feeling like there is too little oxygen in her lungs.”

At Galligan and Madden’s level of competition, performances are decided by fractions of inches and split-seconds of speed. Every bit of breath is critical.

As its name suggests, inflammatory airway disease is caused by inflammation. Inflammation is the body’s natural response to irritating particles, including allergens, that find their way into the respiratory tract. Relatively large particles — those measuring five microns and above — are usually trapped in the upper airway and easily expelled.

Smaller particles, however, can slip past these defenses. Wherever they settle, they cause inflammation that constricts airflow and impedes the transfer of oxygen to the bloodstream and the removal of carbon dioxide from it. Unfortunately, these particles are everywhere, even in a well-kept barn: hay and bedding being the two biggest sources.

Reducing Respiratory Irritants

It is ideal to keep horses outdoors when weather and air quality allow, but that’s not an option for many owners. For most, looking at the stable from the horse’s perspective is the best approach to reducing harmful respiratory irritants. That’s the advice of Dr. Burnley, the veterinarian whose perspective is enhanced by her own experience with asthma.

“You want to decrease any of those particles that are in the horse’s zone of inhalation,” she said. “Put your head down where your horse’s head is and inhale deeply. Stick your nose into their bale of hay. Walk down the aisle when somebody is sweeping or blowing the dust around. As an asthmatic, I am not happy with all the things I come across. We can influence that zone, and that’s what stable management should be all about.”

Dr. Burnley uses and recommends a Haygain hay steamer because it eliminates nearly all respirable particles commonly found in hay. Minimal bedding and low-dust options further reduce breathable dust. Monitoring arena footing and maintaining it as needed to minimize the particles that rise from it are more good basics.

“Open the barn doors and windows for ventilation,” she advised. “Horses are not made to be closed in.”

Although the signs of respiratory struggle can be subtle, resolving them often has obvious performance payoffs. As Galligan described it after recognizing and addressing his mare’s challenges, “She felt like when the effort was not as big and her mind is clear because she is getting the oxygen she needs.” Having owned the 12-year-old “Jordan” since she was four, the horseman is primarily happy to have her feeling her best self again. Three Grand Prix wins on the West Coast winter circuit, including March’s $250,000 CSI4*, are recent performance bonuses for her improved respiratory health.

Photos: KTB Creative group, Shelley Paulson, and Courtesy of Dr. Wren Burnley