SUSPECTED CAUSES

• Horses live, eat, and work in a dust - laden environment.
• Some horses work in urban areas, which are polluted.
• Dust and air pollutants contribute to SAID.
• Dust is composed of molds, bacteria and their toxins, minerals, insect parts, and various chemicals – all stuff things that can’t be seen with the naked eye.
• Air pollutants are mostly gases, like ozone, sulfur dioxide, and nitrous oxide, but particulate matter, such as heavy metals, carbon, and smoke, contribute to pollution exposure in urban horses.
• Air within the stable can be polluted with ammonia, bacterial byproducts (e.g. endotoxin), molds and other chemicals which irritate the airways.

How Allergens Cause SAID

• The horse’s lung is huge – it samples thousands of gallons of air in just a few minutes of intense exercise.
• Dust particles enter airways and are trapped on their inner surface.
• Dust, gases, and chemicals severely irritate the sensitive airway lining.
• The airways, which are active living issue, mount a rapid and aggressive defense called inflammation.
• The extent of this reaction appears to depend on the susceptibility of the horse.
• Some horses mount a stronger, more prolonged defense reaction, which can cause more harm than good.
• It has been speculated that viral infections can precipitate SAID.
• Airway inflammation results. Mucus and cellular debris accumulate within the airways; the airway walls thicken, constrict or collapse.