6 Questions to Consider About Your Horse's Cough

It sounds like someone is blowing through the end of a vacuum cleaner tube—that loud, abrupt, hollow noise exploding from your horse’s open mouth when he coughs.

When you hear it, maybe you’re the type of owner who hushes everyone around so you can hear if he coughs again. Or maybe you’re the less worrisome type, telling yourself, “No big deal; everyone coughs sometimes.”

The truth is, some coughs aren’t important, and others are. In this article you’ll learn to sift through the types of equine coughs and get a better idea of how veterinarians diagnose and treat them.

The best way to get started, our sources say, is to answer these six critical cough questions.

1 / When and Where?

What situations set off your horse’s cough? “Is it associated with feeding grain or feeding hay? Coming into the barn or going out into the field? Riding or some other activity?” asks Erica Lacher, DVM, owner of Springhill Equine, in Newberry, Florida. “This information points me in the direction.”

Feed-related coughs could be due to a hyperreactive pharynx, while forage-related ones suggest a food, fungal spore, or pollen allergy, Lacher says. Horses that cough coming into the barn might be having an allergic response to dust or airborne ammonia. If allergies develop into equine asthma—which is more common in older horses—the airways swell, narrow, and fill with fluid. Summer pasture-associated asthma is the No. 1 reason pastured horses cough, she adds.

Coughing when starting to exercise might be mild mucus-clearing, which is fairly common—akin to a human athlete clearing the morning crud out of the airways. “Those coughs don’t necessarily bother me,” Lacher says.

Coughs that persist throughout an exercise session, however, could point to infection, inflammation like asthma, or a functional issue like a displaced soft palate, says Emmanuelle van Erck-­Westergren, DVM, PhD, Dipl. ECEIM, of Equine Sports Medicine Practice, in Waterloo, Belgium.

Coughing after exercise, especially intense workouts, could mean blood in the lungs, Lacher says. While exercise-induced pulmonary hemorrhage (EIPH) isn’t usually life-threatening, it could lead to lung scarring over time.

Horses that “coffart”—a term Lacher jokingly uses in practice to describe simultaneous coughing and ­flatulence—are strong candidates for asthma diagnosis. “For me, the coffart is always asthma until proven otherwise,” she says.

2 / How much?

One-off coughs are rarely worth worrying about—the horse is often just expulsing a little food that slipped down the wrong way, van Erck-Westergren says. “But when you see a pattern in your horse’s coughing, these are signs he’s got something in his airways that needs to be worked up. It’s not normal for anyone—horse or human—to cough regularly.”

Lacher agrees: “Because we usually expect our horses to be athletes—even at a low level—anything more than a few coughs would be something I’d want to investigate.”

While regular coughing could indicate the horse has allergies or mild airway disease, frequent coughing might mean a more serious issue such as severe asthma or pneumonia, she adds. “If they can’t seem to stop coughing, or they can’t catch their breath, or they’re coughing 25 times  in a row during a meal, that’s pointing me toward something pretty bad,” she says. “Call your veterinarian immediately.”

3 / Does Anything Come Out the Nose?

Like humans, horses sometimes cough up various kinds of goo—from clear, thin liquids to thick, sticky, colorful, and often smelly pastes. But unlike humans, horses typically drain airway mucus through the nostrils rather than the mouth.

Clear or white discharge suggests asthma, allergy, or a transient viral infection. Thicker production that’s tinged yellow or green can mean a bacterial or fungal infection. (A thick and very smelly nasal discharge without a cough is a strong sign of a tooth infection, Lacher adds.)

Dry coughs could hint at irritation, like an intolerance to ammonia, says van Erck-Westergren. But a dry nose doesn’t necessarily mean the horse’s cough isn’t productive. Horses can cough up mucus into the throat and then swallow it, she says. And sometimes the mucus is so thick it sticks to the airway walls and won’t come up. “You have the impression it’s a dry cough, but the difference between what’s going on inside and what you see outside can be really dramatic,” she says.

Something you do want coming out of your horse’s nostrils is air. Respiratory issues in horses can restrict the lower airways and the nasal passages. Because horses can’t breathe through their mouths like people can, they don’t breathe well when their nasal passages are clogged.

“Put your hand in front of the nose and feel for air coming out,” Lacher says. “Sometimes I get one that’s barely pushing any air, and then I really throw the drugs at them because they’re barely breathing.”

4 / Is Anything Else ‘Off’?

Coughs often come packaged with other signs of illness, such as fever. Rectal temperatures above 102.5 degrees F indicate infectious disease, including pneumonia, says Lacher. Swollen lymph nodes at the throatlatch could also suggest infection, van Erck-Westergren adds.

Fatigue is another indicator, she says. Horses with chronic lower airway inflammation might not cough frequently, but they’ll be lethargic. “If you have a coughing horse that struggles to stay energetic throughout his workout or takes a longer time to recover, he might have developed significant lower airway inflammation.”

If the airways are constricted due to inflammation, horses must work harder to breathe, contracting their abdominal muscles to push air out and appearing to “breathe through the belly,” says van Erck-Westergren.

Horses with tracheal irritation show sensitivity around the larynx, and they might cough if you gently pinch that area, she adds.

If they cough while stretching out the neck during riding and fight the rein, she says, they could have a mechanical issue in the upper airways, such as displacement of the soft palate.

5 / Are Other Horses—or People— Coughing?

When several horses on the same farm start coughing, it should promptly raise red flags about a possible infectious disease outbreak. Lacher says to employ biosecurity techniques immediately; airborne pathogens (disease-causing ­organisms) spread easily in droplets expelled during coughing, so affected horses should be separated and the farm quarantined even before you get test results.

Horses—especially the younger ones that, “like kids at day care,” have not yet developed immunity to many agents—pick up infectious airway diseases such as herpesviruses and pneumonia from other horses, often at shows, Lacher says. Because stress can weaken the immune system, coughing that begins within a few days after travel also suggests infection.

Multiple individuals coughing, however, isn’t always an outbreak, says van Erck-Westergren. Elevated levels of dust, ammonia, or pollen could trigger coughing spells in both humans and equids. “When everyone’s coughing, sometimes there’s a tendency to just reassure ourselves that it’s normal because it happens to everyone,” she says. “But if a horse is coughing regularly and others—even humans—are coughing too, a good look at the environment is the first place to start.”

6 / How Do the Throat and Lungs Sound?

While owners should rely on their veterinarians’ expertise to sort out airway sounds, they can still listen to their horses’ breathing using a home stethoscope to familiarize themselves with what’s normal for their horse. Starting at the throat, they can check for rattling noises in the trachea that indicate mucus moving around, Lacher says.

Then they can move to the lungs, located in a triangular region stemming from the elbow, to a few inches below the withers, to the top of the flank whorl. Any crackling—“which sounds like (wet) Rice Krispies,” she adds—or wheezing suggests trouble in the lungs.

Wheezing occurs when airway channels narrow, so they sound high-pitched, like wind slipping through a cracked door, says van Erck-Westergren. If it’s asthma, the lungs usually sound noisier higher up, whereas pneumonia impacts the tissues lower down, Lacher says.

Hearing equine respiratory sounds, however, can be challenging because of the many layers of tissue—mainly ribs and muscles—between the lungs and the stethoscope. Veterinarians might accentuate the sounds by placing a plastic bag over the horse’s nose for a few breaths so he then must breathe deeply. 

Working Up the Cough

Lacher says she starts her cough calls with these questions, followed by a physical exam that includes putting both hands in front of the nostrils to check for even, appropriate airflow and listening to the throat and chest for wheezes and crackles.

Often, veterinarians can make a diagnosis based on this physical exam alone, she says. Occasionally—especially if the cough hasn’t improved with management (see sidebar on page 16)—they run laboratory tests.

If they suspect upper airway issues, they can run a needle into the throat between the ridges of the trachea to grab tracheal fluid samples, in a procedure called a transtracheal wash (TTW).

If the lower airway is the target, they can perform a bronchoalveolar lavage (BAL), in which they flush sterile saline through a small nasal tube into the alveoli—tiny pockets in the lungs where gases get exchanged via blood vessels—and then draw it back out. Microscopic analysis of the liquid can reveal the cells the lower airways are harboring.

Medical Treatments

A quick and powerful treatment for most coughs is corticosteroid therapy (administered via nebulizer or systemically), which works as an anti-­inflammatory, Lacher says. But due to their multiple side effects, steroids aren’t good long-term solutions. Non-steroidal anti-­inflammatories also work well, but they, too, can have side effects.

Antihistamines don’t work as well in horses as in humans, she says. However, inhalant therapy is available for asthmatic horses, with promising study results supporting its use.

Targeted immunotherapy can help horses with identified allergies. “Essentially, we teach horses’ immune systems that these things are not as bad as they think they are,” Lacher says. The process usually takes 12 to 18 months, “but we get good and very long-lasting results.”

While cough syrups exist for horses, “they work about as well as they do in humans, which is not very well until you get into the big drugs like hydrocortisone (a steroid),” says Lacher. Even so, they can be useful for young horses with their first viral infections needing symptom relief.

Veterinarians might also prescribe antibiotics, antivirals, or antifungals to target the pathogen found in horses’ samples.

Take-Home Message

A little cough now and then might not raise concerns, but frequent or persistent coughing merits owner and veterinary attention. Physical exams and laboratory testing can pinpoint the cough’s cause—most commonly asthma, allergies, and infectious disease—and guide the veterinarian’s choice of treatment. While drugs can provide quick relief, long-term solutions to coughing often require changes in management to reduce exposure to dust, ammonia, and other allergens.