07/18/2026
🌫️ 𝐏𝐨𝐨𝐫 𝐀𝐢𝐫 𝐐𝐮𝐚𝐥𝐢𝐭𝐲: 𝐖𝐡𝐞𝐧 𝐂𝐚𝐧 𝐇𝐨𝐫𝐬𝐞𝐬 𝐑𝐞𝐭𝐮𝐫𝐧 𝐭𝐨 𝐖𝐨𝐫𝐤?🐴
In the last 20 years, wildfires have become more frequent, more intense, and larger, with the greatest increase in extreme fire behavior observed in the western United States and the northern parts of North America and Russia.
These extreme fire events have contributed to periods of poor air quality that negatively impact the respiratory health of both people and animals.
𝐖𝐡𝐚𝐭 𝐚𝐫𝐞 𝐏𝐌𝟐.𝟓 𝐚𝐧𝐝 𝐰𝐡𝐲 𝐚𝐫𝐞 𝐭𝐡𝐞𝐲 𝐬𝐨 𝐡𝐚𝐫𝐦𝐟𝐮𝐥?
These negative impacts are largely attributed to the small particles known as PM2.5 that are present in smoke. PM2.5 are microscopic airborne particles that are about 30 times smaller than the width of the average human hair. This means they can easily sneak past the body's natural defenses.
As they are inhaled, they may cause immediate irritation and inflammation of the airways, resulting in coughing or shortness of breath. However, because these particles are inhaled deep into the lungs, they can pe*****te the alveoli, enter the bloodstream, and impact organs throughout the body. This can damage the lining of blood vessels and lead to systemic inflammation and oxidative stress.
These health effects are most commonly observed when the Air Quality Index (AQI) exceeds 151 on a scale of 0 to 500. However, negative impacts may occur at lower AQI levels in horses with underlying respiratory or cardiovascular conditions.
𝐇𝐨𝐰 𝐝𝐨𝐞𝐬 𝐦𝐲 𝐡𝐨𝐫𝐬𝐞 𝐫𝐞𝐜𝐨𝐯𝐞𝐫 𝐟𝐫𝐨𝐦 𝐩𝐨𝐨𝐫 𝐚𝐢𝐫 𝐪𝐮𝐚𝐥𝐢𝐭𝐲?
While many horse owners monitor the current AQI and make the necessary adjustments to reduce health risks, they often don't realize that poor air quality can continue to affect the body even after the AQI returns to healthy levels. This is because the body needs time to remove the particles and repair damaged tissues.
The lungs rely on natural clearance mechanisms, including coughing and tiny hair-like structures called cilia, to move particle-filled mucus out of the respiratory tract. For particles that have entered the tissues, specialized white blood cells called macrophages engulf and remove them. Once exposure stops, the body also begins repairing damaged cells and resolving oxidative stress by neutralizing the free radicals responsible for inflammation and tissue damage.
Unfortunately, these processes take time. While the healing process is estimated to take 4 to 6 weeks, the exact timeline depends on several factors:
🔹 The extent and duration of exposure. The poorer the air quality and the longer the exposure, the more time a horse will need to recover. For example, an AQI of 400 is expected to cause more damage and require a longer recovery period than an AQI of 150.
🔹 Horse management during exposure. Horses may require more time to heal if they continued working or participated in activities during periods of poor air quality. Exercise, hauling, or even running and playing during turnout increases respiratory rate, resulting in greater inhalation of PM2.5 particles and increased overall exposure.
🔹 The horse's health before exposure. Horses that are out of shape or have pre-existing respiratory or cardiovascular conditions may require a longer recovery period. Every horse should be evaluated individually when developing a return-to-work plan.
𝐖𝐡𝐞𝐧 𝐜𝐚𝐧 𝐦𝐲 𝐡𝐨𝐫𝐬𝐞 𝐫𝐞𝐬𝐮𝐦𝐞 𝐰𝐨𝐫𝐤?
Current recommendations from Oregon State University and UC Davis suggest allowing horses to rest for a minimum of 7 to 14 days under healthy air conditions before returning to work. More conservative recommendations suggest that 4 to 6 weeks is ideal to allow the respiratory tract to heal fully and reduce the risk of re-aggravating the airways.
A "healthy air day" is generally considered a 24-hour period during which the AQI remains below 100.
After the appropriate recovery period, healthy horses should return to work gradually, beginning with hand walking. Throughout the process, monitor your horse closely for signs of respiratory distress, including:
🐴 Coughing
👃 Nasal discharge
😮💨 An elevated respiratory rate
🚫 Reluctance to work
If any of these signs develop, reduce the workload and consult your veterinarian.
𝐒𝐨 𝐰𝐡𝐚𝐭 𝐝𝐨𝐞𝐬 𝐚𝐥𝐥 𝐨𝐟 𝐭𝐡𝐢𝐬 𝐦𝐞𝐚𝐧?
I want to take a moment to emphasize that I am not a veterinarian; rather, I have a Ph.D. in Equine Science. However, here's how I interpret the current recommendations:
When developing a recovery plan, many factors need to be considered. As I dug deeper into the 4- to 6-week recommendation, it appears to have originated from UC Davis during years when California experienced severe and prolonged wildfire smoke exposure. While 4 to 6 weeks may be ideal, UC Davis also acknowledged that many owners of performance horses may wish to return to work sooner, and that horses experiencing only mild smoke exposure may require a shorter recovery period.
Based on those recommendations, a 2- to 4-week recovery period may be reasonable for horses with relatively mild smoke exposure that remain clinically healthy, while 4 to 6 weeks is a more appropriate goal following prolonged or severe exposure.
When returning to work, don't expect your horse to immediately resume its previous workload. Start with hand walking and walking under saddle for at least a week before gradually reintroducing trot and, eventually, canter work.
Finally, remember that every horse is different. What works well for one horse may not be appropriate for another. Fitness level, age, pre-existing health conditions, the severity of smoke exposure, and individual response all play important roles in determining how quickly a horse can safely return to exercise.
𝐓𝐡𝐞 𝐁𝐨𝐭𝐭𝐨𝐦 𝐋𝐢𝐧𝐞
I know it's frustrating, especially in the middle of competition season, and it may feel like a setback. However, patience is one of the best investments you can make in your horse's long-term respiratory health.
Returning to work too soon can prolong the healing process and potentially worsen existing airway damage. By managing your horse appropriately during periods of poor air quality, allowing adequate recovery time, and gradually returning to work while monitoring for signs of respiratory distress, you'll give your horse the best opportunity for a full recovery.
Cheers,
Dr. DeBoer
