Why is My Horse Coughing?

It’s not unusual for a horse to cough and there are numerous reasons this can happen. Just as with humans, a cough can be as simple as a reaction to dusty conditions or the sign of something serious.

So why is your horse coughing and how do you know if it warrants a visit from the veterinarian?

When Armon Blair, DVM, of Ocala Equine Hospital in Ocala, Florida, gets a call from a client about a coughing horse, there are several questions he asks up front:

• What is the horse’s age?
• Does the horse have a fever?
• When does the horse cough?
• Is the coughing at a certain time of year?
• How frequent is the cough?
• What is the character of the cough?

The answers to these questions help the veterinarian determine if an exam is advisable.

“A coughing horse is a very common call for veterinarians, and the range of coughing is huge,” says Blair. “Most of the horses I see for coughing aren't infectious but are allergic and caused by environmental issues.”

What is the horse’s age?

“The age of the horse will put the veterinarian’s thought process in a certain direction,” says Blair. “If a foal is coughing, it’s more likely a sign of sickness. When an adult horse is coughing, allergies are the most common cause in horses I see.”

Does the horse have a fever?

“Any time you have a coughing horse, you want to take his temperature to check if he has a fever,” says Blair. “A fever isn’t always associated with a cough, but a lack of fever doesn’t mean the cough is not infectious.”

Many horse owners don’t take temperatures unless they suspect illness. You should take your horse’s temperature often enough that you have a baseline for what is normal for him. This way you’ll know if he’s running a fever.

When does the horse cough?

Is it when he’s eating grain or hay? When he’s exercising or being ridden? When he’s at rest?

“It’s more common for an owner to call with concerns because their horse is coughing during feeding time and when exercising,” says Blair. “It’s less common but more concerning if the horse is at rest and coughing.”

Is the coughing at a certain time of year?

Is it just seasonal at a specific time of year, or does the horse cough year-round?

Coughing only at a certain time of year is more indicative of allergies than illness.

“In Florida, we have a big run on fall allergies when certain weeds are blooming,” notes Blair. “I see many more allergy-related issues with horses in the fall than in the spring, which is typically the opposite of human allergies.”

Blair points out that during winter months in cold climates, coughing from dust and mold is common because horses often spend more time shut up in a barn.

“Dust, mold and ammonia in a closed-up environment can contribute to coughing,” he says. “When horses are outside and in a mild climate, I find that coughing is more often caused by environmental issues.”

How frequent is the cough?

“If the horse typically coughs two or three times when you start longeing or riding him and then quits, it’s likely not serious,” says Blair. “More concerning would be a cough that is persistent or very deep.”

What is the character of the cough?

Is it a light, hacking cough or is it a deep cough?

Exam for the coughing horse

If your answers to the above questions prompt your veterinarian to schedule an exam, it will typically involve some or all of the following:

• Taking the horse’s temperature
• Listening to the lungs with a stethoscope
• Drawing blood to run a complete blood count (CBC)
• Performing an endoscopy 

If these steps reveal no definitive reason for why the horse is coughing, a further diagnostic exam could include:

• Performing a transtracheal wash followed by lab culture and cytology

“Whenever I'm examining a horse for coughing, I always take his temperature to check for fever, and then listen to the chest (lungs) with a stethoscope to check for abnormal sounds,” says Blair.

“I may also pull blood for a CBC to see what white blood cells are present. Sometimes allergies can be detected this way,” he notes, adding that blood test results can also indicate if an infection is present.

“We may also do an upper airway endoscopy, or ‘scope’ the horse, looking for mucus in the trachea. Sometimes scoping can reveal the cause of a cough. For example, if there is infection in the guttural pouches, mucus can drain into the pharynx and cause coughing,” Blair explains.

If the veterinarian is still unsure of the reason for the horse’s coughing, a transtracheal wash is usually the next step. Blair says that rather than a first choice, this is typically a “down the road” option for veterinary diagnostics when an infectious lung disease is suspected.

For this procedure, the horse is sedated and a local anesthetic is used as well. A small incision is made in the neck so sterile saline can be injected through a catheter into the lungs via the trachea. Fluid is then aspirated out and is sent to a laboratory for culture and cytology evaluation. The results of the lab work will enlighten the veterinarian as to further treatment and any necessary medication.

Treating the cough

“You don't want to overtreat an occasional cough,” says Blair.

If a veterinary exam reveals that the coughing is caused by allergies, one of the first lines of defense is to treat the horse with antihistamines.

Any other treatment or medication would be recommended by your veterinarian for your horse’s specific situation. You may also want to try an over-the-counter cough remedy, like Farnam’s Cough Free^® respiratory health pellets.

Smart Horsekeeping

Do your part to make sure stable management practices aren't contributing to your horse’s coughing.

• Keep horses outside as much as possible.
• Use the cleanest, least dusty bedding you can get.
• Clean stalls well every day and remove ammonia-soaked bedding.
• Put horses outside while you’re cleaning stalls and aisles.
• Don't sweep or blow out the barn while horses are inside.
• Don’t store hay or straw in loft areas directly over stalls.
• Ventilation is crucial! Don’t seal up barns tightly, even during the winter.