The severe fires in southern California have exposed humans and animals to unhealthy air containing wildfire smoke and particulates. These particulates can build up in the respiratory system, causing a number of health problems including burning eyes, runny noses, and illnesses such as bronchitis. They can also aggravate heart and lung diseases such as congestive heart failure, chronic obstructive pulmonary disease, emphysema, and asthma.


Because little information is available to horse owners and even equine veterinarians on the effects on horses of breathing air laden with particulates, some suggestions are offered here to serve as a general guide.


What’s In Smoke?


Smoke is made up of carbon dioxide, carbon monoxide, particulate matter, soot, hydrocarbons, and other organic substances including nitrogen oxides and trace minerals. The composition of smoke depends on what is burned; different types of wood, vegetation, plastics, house materials, and other combustibles all produce different compounds when burned. Carbon monoxide, a colorless, odorless gas that is produced in the greatest quantity during the smoldering stages of the fire, can be fatal in high doses.


In general, particulate matter is the major pollutant of concern in wildfire smoke. Particulate is a general term used for a mixture of solid particles and liquid droplets found in the air. Particulates from smoke tend to be very small (less than one micron in diameter), which allows them to reach the deepest airways within the lung. Consequently, particulates in smoke are more of a health concern than the coarser particles that typically make up road dust.


How Smoke Affects Horses


The effects of smoke on horses are similar to effects on humans: irritation of the eyes and respiratory tract, aggravation of conditions like heaves (recurrent airway obstruction), and reduc