Wildfires have raised concern among horse owners regarding the potential impact of persistent smoke and related air pollution on their equids. And their concern is justified: Smoke can cause serious health problems for horses, as it can in people, notes an equine veterinarian from the University of California, Davis (UC Davis), School of Veterinary Medicine.

Smoke is an unhealthy combination of carbon dioxide, carbon monoxide, soot, hydrocarbons, and other organic substances. Smoke particulates, which are a mixture of solid particles and liquid droplets in the air, can irritate horses’ eyes and respiratory tracts, and hamper their breathing.

“Owners should limit their horses’ activity when smoke is visible,” said UC Davis veterinary professor John Madigan, DVM, MS, Dipl. ACVIM, ACAW.

During California wildfires with persistent smoke several years ago, the Tevis Cup—a 100-mile endurance race—was postponed based on adverse air quality for exercising horses. This is an example of important management decisions that can protect horse health.

It is important to use human health air-quality advisories and apply them to horse events where horses will be exercising and breathing harmful smoke. If humans’ eyes burn and are bothered by smoke,  you can assume horses will be in the same boat. Providing horses with resting from exercise, limiting smoke exposure when possible, and monitoring for signs of increased respiratory rate or cough should be at the top of owners’ to-do lists when wildfires are near. And should a concern arise, always consult your veterinarian.

“It’s also important to provide horses with plenty of fresh water, which keeps airways moist and helps them clear inhaled particulates,” said Madigan.

If a horse is having difficulty breathing, contact your veterinarian immediately to ensure the horse has not developed a reactive airway disease or bacterial infection accompanied by bronchitis or pneumonia. Horses can suffer from constriction of the airways, just as humans can.

In cases of heavy smoke exposure, it can take four to six weeks for smoke-induced damage to heal, during which time the horse should not be heavily exercised. Premature exercise could aggravate the condition, delaying healing and compromising the horse’s performance for weeks or months.

“If the horse has further smoke-related problems, such as persistent cough, nasal discharge, fever, or increased rate of breathing or labored breathing, the owner should contact a veterinarian, who may prescribe respiratory medications such as bronchial dilators or other treatments that will hydrate the horse’s airway passages and reduce inflammation,” Madigan said. “The veterinarian also may recommend tests to determine whether a secondary bacterial infection is contributing the horse’s respiratory problems.”