As illustrated by recent wildfires in Southern California, smoke and related air pollution from wildfires pose serious health problems for horses, as well as people, notes an equine veterinarian at the 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, irritate horses' eyes and respiratory tracts, and hamper their breathing.

"Owners should limit their horses' activity when smoke is visible," said veterinary professor John Madigan. "It's also important to provide them with plenty of fresh water, which keeps airways moist and helps the horse clear inhaled particulates."

Because horses drink most of their water within two hours after eating hay, it's especially important to provide the water close to their feeders. To minimize the horse's exposure to dust, which can cause further irritation, owners should feed dust-free hay or actually soak the hay in water before giving it to the horse, Madigan suggests.

If the horse is having difficulty breathing, a veterinarian should be brought in to make sure the horse has not developed a bacterial infection accompanied by bronchitis or pneumonia.

It may take four to six weeks for smoke-induced damage to heal, during which time the horse should not be exercised. Premature exercise may aggravate the condition, delaying healing and compromising the horse's performance for many weeks or months.

"If the horse has further smoke-related problems, such as persistent cough, nasal discharge, fever, 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."