Horses in the Oregon Wildfire Smoke

What can horse owners do to prevent illness from Oregon's wildfire smoke?

Headlines have been filled with heartwarming stories of horses being rescued and evacuated from the Oregon fires. The Holiday Farm Fire up the McKenzie River from Eugene-Springfield and the Riverside, Beachie Creek and Lionshead fires all crept into the wildland-urban interface, what wildland firefighters call the WUI (wooey), which is where many farms and stables are located. 

Currently the fire danger seems to be reduced, and humans and horses are now dealing with more than a week of hazardous air quality. And that air has moved from Oregon and California, where fires are also burning, up into Washington and even across the country. 

Horses don’t have N95 masks and most barns can’t be locked up airtight. So horse owners are trying to figure out first how to support their animals in this, and then how to help them recover. 

Dr. Erica McKenzie, professor of large animal internal medicine at Oregon State University, was able to answer some questions via email. And some of the vets of Northwest Equine Performance, together with California-based vet Phoebe Smith of Riviera Equine Internal Medicine and Consulting, put together an informative video on the topic.

Here are some of the takeaways from the vets.

In their video, Smith and Dr. Austin Rowland dialogue with Dr. Mark Revenaugh and point out that the main work studying the effects of smoke has actually been done on humans, but the human studies can be extrapolated from for horses. It’s PM 2.5, aka small particulate matter, that is a source of danger to horse and human airways, and as Smith says, can get stuck in horse and human lungs. 

McKenzie says, “It is so challenging for our outdoor animals right now!” She adds that the most challenging thing to their airways is the PM 2.5 and “it is likely to be bad for some time to come.”

McKenzie says since it is impossible to protect the vast majority of large animals from smoke, taking other measures to reduce respiratory stressors is therefore important — moistening feed, particularly hay, to reduce dust inhalation; avoid use of dusty bedding materials, ensure vaccines for respiratory disorders are up to date, use a sprinkler for dusty or ashy ground. Avoid any forced exercise since this can “massively increase the amount of air passing through a horse’s respiratory tract.”

Smith says that the guidelines for human athletes serve as a guide for exercising horses — and an air quality index of more than 200 is not safe to exercise in. Much of Oregon has had readings above 400 for the past week. 

She adds that we know that with hazardous air, human hospitals see increased cases of respiratory distress, high blood pressure and even cardiac disease — ”we don’t know about cardiac events in horses,” she says. 

So when the air quality is more than 200 and the color purple on the AQI, you don’t exercise, but what about when the sky is blue again?

McKenzie says, “A common recommendation that is based on reasonable assumptions is that four to six weeks will likely allow healing and restitution of the damaged respiratory tract.”

Smith in her discussion with the vets of NWEP agrees with that but expands upon it.

She says horses exposed to the levels of smoke we have experienced in the Northwest should rest for a minimum of two weeks, maximum of six weeks. “Two weeks would be the bare minimum of respiratory rest, not breathing hard, fast or deeply.”

She continues, “There is a lot of evidence to suggest that is the minimum,” and recommends starting with handwalking then walking under saddle in week two “but walking, so the horse is not moving a ton of particulates in or out.” After that she says you can start to ramp up, but watch your horse. “Everybody has to be attuned to their horse.” If the horse is coughing, then it’s time to call your vet.

She says that a horse’s VO2 max (maximum rate of oxygen consumption measured during incremental exercise) is shown to be reduced up to 20 days after smoke exposure. And she says if horses are not getting adequate oxygen, it also affects the brain, tendon, limbs etc., 

And in a worst case scenario a horse can develop bronchoconstriction, a tightening of the airways.

 McKenzie says in terms of what to look out for, “many animals are going to show mild signs of compromise and this is unfortunately to be expected.” The signs include sneezing or snorting, intermittent coughing, particularly if exercising, which she points out people should try to avoid right now, and mild nasal discharge that might look clear or have dust in it. “The animal should remain bright with an appetite however,” she says. 

Smith also says to look for nostril flaring and that a horse’s breathing should not be more than 12-24 breaths per minute. Note if your horse just seems off a little bit, not eating quite normally or a little despondent.

Many horse owners want to ward off any problems, and are scouring the internet for supplements and cures. McKenzie says, “at times of crisis misinformation is common and circulates rapidly. It is important that people seek out and utilize verified sources of information including university websites, veterinary association websites, veterinary clinics and veterinarians.”

Many horse owners have been looking into buying a nebulizer or paying for treatments using nebulizers with colloidal silver. Of this, McKenzie says, “Unfortunately there is limited evidence supporting the use of nebulization at this time. If there are benefits, they are likely very transient, and some treatments could actually be counterproductive, for example, using bronchodilators might worsen coughing or open the airways to permit greater particle penetration.”

She says a study was released this year “showing smoke inhalation from a bushfire situation created mild asthma in previously healthy polo horses, and treatment with a corticosteroid and a bronchodilator did not alter the clinical disease. The most critical thing was to reduce PM 2.5 inhalation.”

For supplements, the vets of NWEP point to liquid or natural vitamin E as an antioxidant, fatty acids and a supplement called Aleira which has shown results in studies.

Smith also addressed nebulizers saying that saline nebulizing in the right horses is appropriate for certain situations, as long as the nebulizer cleaned really well between treatments and dried. When it comes to nebulizing essential oils or using colloidal silver, she says “no.” Some horses nebulized with the silver treatment develop an irreversible irritation of the airways, Smith warns.

For McKenzie, “The most critical thing is use good quality non-dusty feeds and bedding, and moisten feed and any surfaces the animals will travel on.”

Smith also recommends moisture, saying keep horses drink the most water while eating hay, so keep water near the hay and “wet hay is fantastic.” It’s important to keep airways moist, she says, because dry airways are sort of sticky and particulates tend to stay there” she says. And of course, respiratory rest. 

McKenzie also recommends being prepared for disaster following the guidelines from the American Association of Equine Practitioners. She reminds horse owners, “Above all, make sure your animal is identifiable! Ideally microchipped!” 

To watch the video with NWEP and Dr. Smith, go here or see below. They also supplied their recommendations in a flyer

And for another interview with Dr. McKenzie go here.