• Limit exercise when smoke is visible. Don’t have your horse do activities that increase the airflow in and out of the lungs. This can trigger bronchoconstriction (narrowing of the small airways in the lungs).

• Provide plenty of fresh water close to where your horse eats. Horses drink most of their water within 2 hours of eating hay, so having water close to the feeder increases water consumption. Water keeps the airways moist and facilitates clearance of inhaled particulate matter. This means the windpipe (trachea), large airways (bronchi), and small airways (bronchioles) can move the particulate material breathed in with the smoke. Dry airways make particulate matter stay in the lung and air passages.

• Limit dust exposure by feeding dust-free hay or soak hay before feeding. This reduces the particles in the dust such as mold, fungi, pollens and bacteria that may have difficulty being cleared from the lungs.

• If your horse is coughing or having difficulty breathing, have your horse examined by a veterinarian. A veterinarian can help determine the difference between a reactive airway from smoke and dust versus a bacterial infection and bronchitis or pneumonia. If your horse has a history of having heaves or recurrent airway problems, there is a greater risk of secondary problems such as bacterial pneumonia.

• If your horse has primary or secondary problems with smoke-induced respiratory injury, you should contact your veterinarian who can prescribe specific treatments such as intravenous fluids, bronchodilator drugs, nebulization, or other measures to facilitate hydration of the airway passages. Your veterinarian may also recommend blood tests or other tests to determine whether a secondary bacterial infection has arisen and is contributing to the current respiratory problem.

• Give your horse ample time to recover from smoke-induced airway insult. Airway damage resulting from wildfire smoke takes 4-6 weeks to heal. Ideally, plan on giving your horse that amount of time off from the time when the air quality returns to normal. Attempting exercise may aggravate the condition, delay the healing process, and compromise your horse’s performance for many weeks or months. While we recognize that owners and trainers of sport horses may want to return to work sooner than 4-6 weeks, Dr. Kent Pinkerton* recommends that horses return to exercise no sooner than 2 weeks post smoke-inhalation, following the clearance of the atmosphere of all smoke. Horses, like all other mammals, tend to have an irritation to particles, but will recover from the effects within a few days. With the devastation at San Luis Rey Downs (where 46 horses died, mostly from fire or smoke inhalation), it would be wise give the horses a break from exercise and then to gradually re-introduce them back to their routine exercise. On December 10, 2017, Dr. Rick Arthur, equine medical director at the UC Davis Kenneth L. Maddy Equine Analytical Chemistry Laboratory and at the California Horse Racing Board, issued an advisory on behalf of the CHRB regarding horses at the Del Mar racetrack.

• Air quality index (AQI) is used to gauge exercise/athlete event recommendations for human athletes. It may be reasonable to use those for equine athletes as well. For example, the National Collegiate Athletic Association lists the following recommendations on their website: “Specifically, schools should consider removing sensitive athletes from outdoor practice or competition venues at an AQI over 100. At AQIs of over 150, all athletes should be closely monitored. All athletes should be removed from outdoor practice or competition venues at AQIs of 200 or above.” During the Napa area fires, the Napa Valley Unified School District used the AQI to determine when students should return to school. They recommended 2 weeks off based on the AQI which was over 400 and took more than 10 days to resume normalcy.

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*Dr. Kent Pinkerton is a professor in both the medical and veterinary medical schools at UC Davis. His research focuses are on the health effects of inhaled environmental air pollutants to alter respiratory, cardiovascular and neurological structure and function. Special areas of interest include the interaction of gases and airborne particles to produce cellular and structural changes within site-specific regions and cells of the respiratory tract in both acute and chronic timeframes of exposure.