Animal exposure to wildfire smoke

According to Congressional Research Service, in 2019, 50,477 wildfires burned 4.7 million acres nationwide, while in 2020 (as of September 1) nearly 40,000 wildfires have burned over 4.0 million acres (Hoover and Hanson, 2020). Although many are not directly affected by wildfires, the resultant smoke, particulates, and byproducts (such as ash) expose humans and animals to injuries from inhalation of unhealthy air. The air quality can be determined by an Air Quality Index (AQI) and can be easily assessed at the government site AirNow.

The composition of smoke is highly dependable on the nature of its fuel – different types of wood, vegetation, plastics, construction material, etc. However, smoke is mostly made up of carbon dioxide, carbon monoxide, particulate matter, soot, hydrocarbons and other organic substances including nitrogen oxides and trace minerals. According to the United States Environmental Protection Agency (EPA) particulate matter - a mixture of solid particles and liquid droplets found in the air - is the principal public health threat from short-and longer-term exposure to wildfire smoke.

While particles from wildfire smoke can vary in size, approximately 90% of total particle mass emitted from wildfires consists of fine particles (i.e., PM2.5, particles 2.5 μm in diameter or smaller). The effects of particulate matter exposure range from eye and respiratory tract irritation to more serious disorders including reduced lung function, bronchitis, exacerbation of asthma, heart failure, and premature death, affecting humans and animals (Stone et al., 2019).

Common signs of possible smoke or dust irritation in animals

According to the American Veterinary Medical Association (AVMA) animals with cardiovascular or respiratory disease (as observed in humans) are especially at risk from smoke and should be closely watched during all periods of poor air quality resulting from wildfires. Regardless previous health conditions, the list below presents the most common signs of possible smoke or dust irritation in animal.

If any of your animal’s experience any of these signs following exposure to wildfire smoke, please consult your veterinarian:

  • Coughing or gagging
  • Difficulty breathing, including open mouth breathing and increased noise when breathing
  • Eye irritation and excessive watering
  • Inflammation of throat or mouth
  • Nasal discharge
  • Asthma-like symptoms
  • Increased breathing rate
  • Fatigue or weakness
  • Disorientation or stumbling
  • Reduced appetite and/or thirst

During and after animal exposure to wildfire smoke

Limit exercise, especially if smoke is still visible. Reduce animal exercise as much as possible in order to reduce the airflow into the lungs of poor air quality, which can lead to lung damage. This is especially important for horses due to their huge lung capacity.

A study conducted in Calgary (Canada) after the 2018 wildfires, evaluated the impact of poor air quality on exercise performance in polo horses. After performing lung washes researches reported that every horse in the study showed inflammation of the respiratory tract. Further, a reduction in performance was observed, which was only improved after 2.5 weeks of improved air quality. Horses had a 15 % increase in speed, as well as a 13.2 % VO2max, compared to those measures on the first day of improved air quality (Bond, 2019).

Provide animals with plenty of fresh water, which should be strategically located near feeding areas. Proper water intake is important to keep the airways moist and facilitates clearance of inhaled particulate matter. Dry airways make particulate matter remain in the lung and airways, which can potentially worsen the symptoms of smoke exposure, and eventually lead to opportunistic infections caused by bacteria, as respiratory defense mechanisms are compromised (Kuehn, 2013). Therefore, is also important to limit dust exposure by feeding low or dust-free feeds. When possible sprinkling or misting the animal facilities, pens, and/or stalls, to reduce the dust particles.  

Birds, different from other animals (i.e. mammals), have a very particular breathing system, characterized by unidirectional airflow and cross-current gas exchange making them more susceptible to exposure to wildfire smoke. When possible move birds indoors (but in a room with good ventilation), or to locations with better air quality to help reduce complications due to wildfire smoke exposure.

Similarly, pets should be kept indoors to reduce the exposure to smoke from wildfires.  Dog owners should reduce the time spent outdoors and limit physical activities. For dogs that must be walked or exercised outdoors, owners should look for times of the day when smoke and dust settle, and heat is not at peak. Further, moderate to intense exercise should be reduced when there is a high or very high-risk rating (AQI exceeding 100).

It is important to remember that some dog breeds (brachycephalic breeds or flat-faced) such as Bulldogs, Shih Tzus, and Pugs are more susceptible to smoke due to their facial anatomy and will require extra attention.

Injury from smoke inhalation has been shown to be dose dependent, with potential for both immediate and long-term harmful effects to the respiratory system (Cox et al., 2003; Park et al., 2004). After wildfire smoke exposure, allow animals long time for recovery, as airway damage resulting from wildfire smoke can take 4 to 6 weeks to heal (Madigan et al., 2008). Particularly for livestock, the attempt to handle, move, or transport may aggravate observed conditions or delay the healing process, compromising even more the future performance of the animal.

Quality of water and forages after wildfires

Additional to animal injuries caused either by wildfires or exposure to smoke, livestock feed and water sources can often be landed with ashes, making producers concerned about the quality of water and forages after wildfires.

After the 2018 Camp Fire in California, University of California Cooperative Extension  conducted a study to evaluate the quality of forage samples and livestock drinking water at Butte County, region affected during the 2018 wildfires (Schohr et al., 2019). The researchers observed that:

  • Of the forages analyzed, all detectable minerals were well below maximum tolerable levels established for cattle by National Research Consortium (2005).
  • There was not detection of Lead, Mercury, Arsenic, Molybdenum or Cadmium (heavy metals).
  • No detection of any organic compounds belonging to diverse chemical classes (e.g. Pesticides, Environmental contaminants, Drugs and Other natural products).
  • The drinking water samples tested all detectable minerals were below safe concentration limits as established by EPA.
  • There was no detection of heavy metals, or Volatile Organic Compounds (VOC’s).

The authors conclude that the toxicology analysis showed that concentrations were unremarkable for livestock forage and water samples taken in the Camp Fire region. However, sending water and feed samples for analysis after a wildfire is advised before feeding it to livestock.

Wildfire events will happen year after year. The best way to protect your family and animals is to be prepared. Have an evacuation plan ready in advance and follow official guidelines provided. After wildfires seek appropriate professional help for your family and animals.

Tips and Resources

Quick Tips to From AMVA to Protect Livestock

  • Limit exercise when smoke is visible. Especially do not require animals to perform activities that substantively increase airflow into and out of the lungs.
  • Provide plenty of fresh water near feeding areas.
  • Limit dust exposure by feeding low-dust or dust-free feeds and sprinkling or misting the livestock holding area.
  • Plan to give livestock 4 to 6 weeks to recuperate after the air quality returns to normal. Attempting to handle, move, or transport livestock may delay healing and compromise animals’ performance.
  • Have a livestock evacuation plan (see “Large Animals and Livestock in Disasters”) ready in advance. If you don't have enough trailers to quickly transport all of your animals, contact neighbors, local haulers, farmers, producers, or other transportation providers to establish a network of reliable resources that can provide transportation in the event you need to evacuate your animals.
  • Good barn and field maintenance can reduce fire danger for horses and other livestock.  Make sure barns and other structures are stable, promptly remove dead trees, clear away brush, and maintain a defensible space around structures.

Quick Tips to From AMVA to Protect Pets

  • Keep pets indoors as much as possible, and keep your windows shut.
  • Birds are particularly susceptible and should not be allowed outside when smoke or particulate matter are present.
  • Let dogs and cats outside only for brief bathroom breaks if air quality alerts are in effect.
  • Avoid intense outdoor exercise during periods of poor air quality. Exercise pets when dust and smoke has settled.
  • Have a pet evacuation kit (see “Pets and Disasters”) ready and include your animals in your disaster preparedness planning.

Useful Websites

References

Bond, S. L. 2019. Mild Equine Asthma: Effects of Commonly Used Treatments on the Respiratory Microbiota, Inflammatory Gene Expression, and Aerobic Performance during High-Intensity Exercise. University of Calgary.

Cox, R. A., A. S. Burke, K. Soejima, K. Murakami, J. Katahira, L. D. Traber, D. N. Herndon, F. C. Schmalstieg, D. L. Traber, and H. K. Hawkins. 2003. Airway obstruction in sheep with burn and smoke inhalation injuries. Am. J. Respir. Cell Mol. Biol. 29:295–302. doi:10.1165/rcmb.4860.

Hoover, K., and A. L. Hanson. 2020. Wildfire Statistics. Congr. Res. Serv. 1–3.

Kuehn, N. F. 2013. Overview of Respiratory Diseases of Small Animals - Respiratory System.

Madigan, J., D. Wilson, and C. Stull. 2008. Wildfires, Smoke and Livestock.

National Research Consortium. 2005. Mineral Tolerance of Animals: Second Revised Edition.

Park, M. S., L. C. Cancio, B. S. Jordan, W. W. Brinkley, V. R. Rivera, and M. A. Dubick. 2004. Assessment of oxidative stress in lungs from sheep after inhalation of wood smoke. Toxicology. 195:97–112. doi:10.1016/j.tox.2003.09.005.

Schohr, T., L. Forero, J. Davy, D. Lile, J. Stackhouse, D. Macon, J. Harper, and B. Karle. 2019. Camp Fire Implication on Livestock Grazing.

Stone, S., L. Anderko, M. Berger, C. Butler, and W. Cascio. 2019. Wildfire Smoke: A Guide for Public Health Officials. EPA Office of Research and Development, Washington, DC, EPA/452/R-19/901, 2019.

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