Keeping Horses Safe During Periods of Low Air Quality

By Dr Fran Rowe, DVM, PAS

As Canada's leader in equine nutrition, Mad Barn thanks the Equine Institute for featuring this story. To use our air quality index tool, go to https://madbarn.com/equine-air-quality-index

As wildfire seasons become longer and more intense, the resulting poor air quality can pose serious risks to equine health. Horses are highly sensitive to airborne pollutants, and even short-term exposure to smoke can trigger respiratory distress, reduce performance, and compromise overall well-being. Yet, deciding when it’s safe for your horse to be active can be challenging without clear guidelines.

To help horse owners make informed decisions, an Air Quality Index (AQI) tool specifically adapted for horses can assess local conditions and help you tailor your horse’s activity levels accordingly. By combining data on airborne pollutants with practical recommendations for equine care, this tool empowers you to protect your horse’s health before smoke exposure leads to more serious issues.

What is Wildfire Smoke?

Wildfire smoke is a complex mixture of gases, particles, and chemicals generated during the combustion of vegetation and other organic materials. Smoke comprises small particles, known as particulate matter (PM), which can vary in size and composition.

The most harmful components of wildfire smoke include particles less than 1 micron in diameter and toxic gases, such as carbon monoxide, nitrogen oxides, and volatile organic compounds.

Dangers of Smoke Inhalation for Horses

Because smoke particulates are very small, they can penetrate deep into the respiratory system. These particulates and toxic gases lead to inflammation and damage to the small airways, causing disruption in gas exchange at the cellular level.

Smoke affects horses in the same way as humans, resulting in:

• Eye irritation
• Respiratory issues
• Exacerbation of pre-existing respiratory conditions
• Reduction in lung function

Owners might notice nasal discharge, coughing, wheezing, and increased respiratory effort in their horses. Horses exposed to unhealthy air and smoke for prolonged periods may exhibit signs of stress, decreased appetite, lethargy, and decreased performance. In severe cases, acute smoke inhalation can result in organ damage and failure.

Air Quality Index

The Air Quality Index (AQI) was created by the US Environmental Protection Agency (EPA) to measure and communicate air quality conditions on a scale from 0-500. Higher values on the scale indicate poorer air quality and increased health risks.

The AQI takes into account various pollutants such as ground-level ozone, particulate matter (PM2.5 and PM10), carbon monoxide, sulfur dioxide, and nitrogen dioxide.

Equine Air Quality Guidelines

Alta Equine Sports Medicine created the following AQI guidelines for horses to help owners determine if current conditions are unhealthy for themselves and their horses.

• 0 – 50 (Good): Air quality is considered satisfactory, and air pollution poses little to no risk. All activities are appropriate for healthy horses.
  
  
• 51 – 100 (Moderate): Health concerns rise for horses who are unusually sensitive to air pollution. Horses with acute heaves or recovering from respiratory illness should be limited to walks.
  
  
• 101 – 150 (Unhealthy for Sensitive Groups): When smoke is visible, and the AQI is over 100, outdoor physical activity should be minimized to help keep particles out of the deepest part of the lungs. Limit environmental dust if prolonged exposure is expected (wetting hay, supportive supplements, etc.). Horses with heart and lung diseases are at increased risk.
  
  
• 151 – 200 (Unhealthy): This AQI range indicates unhealthy air for all horses. Activity should be limited to a slow walk. Equine events should be cancelled if the AQI is over 150. If an AQI over 150 is expected for several days, halt activity altogether and remain indoors.
  
  
• 201 – 300 (Very Unhealthy): This AQI range indicates very unhealthy air for all horses. Any activity should be halted, and horses kept inside. If the AQI is above 200 and is projected for an extended length of time, consider using a nebulizer device.
  
  
• 301 – 500 (Hazardous): This AQI range indicates hazardous air for all horses. Any activity should be halted, and horses kept inside. If prolonged exposure to an AQI above 400 is expected, consider relocating yourself and your animals until air quality improves.

In regions with prolonged unhealthy AQI (150-500), horses should not return to work for a minimum of two weeks following atmosphere clearance of smoke to allow the respiratory tract time to recover. In cases of severe smoke-induced airway disease, an even longer recovery time is warranted.

Preventive Measures & Management Strategies

Minimizing exposure to airborne pollutants is crucial for your horse’s health and well-being. Some preventative measures to keep your horse safe when dealing with poor air quality and smoke exposure include:

1. Relocation: If wildfires are imminent or if smoke levels are hazardous, consider temporarily relocating horses to an area with cleaner air, such as an indoor arena or a well-ventilated barn.
2. Limit Outdoor Activities: Reduce strenuous exercise and outdoor activities during periods of poor air quality. If possible, horses should be kept in a well-ventilated environment with minimal exposure to the smoke-filled atmosphere.
3. Adequate Ventilation: Ensure proper ventilation in stables and barns to minimize the accumulation of smoke particles. Portable air purifiers or fans with high-efficiency particulate air (HEPA) filters can be employed to improve air quality.
4. Soaking Hay: Soaking your horse’s forage before feeding can help reduce airborne particles and minimize the inhalation of irritants.
5. Provide Adequate Water: Encourage hydration by providing your horse with fresh, clean water. Drinking plenty of water helps keep the airways moist and aids in clearing inhaled particulate matter from the lungs.
6. Veterinary Care: Regular veterinary check-ups and consultations are essential, especially for horses with pre-existing respiratory conditions. Your veterinarian can provide specific guidance and medications to manage any respiratory issues, such as equine asthma.

When to Call Your Veterinarian

Horses with pre-existing respiratory conditions, such as heaves, have a higher risk of respiratory distress when air quality is unhealthy. However, all horses are at risk of respiratory compromise if smoky conditions are severe enough.

In horses, a typical respiratory rate ranges from 12 to 24 breaths per minute, and breathing should not appear to be strained or labored. If your horse has an increased respiratory rate and/or increased respiratory effort (i.e. nostril flaring or abdominal effort), you should contact your veterinarian.