Barn air quality and Respiratory Disease- How it effects you and your horse.

This is the first of what I plan to be a series of notes and perceptions from the ACVIM Forum in Montreal. This an annual meeting of Veterinary Internists and a lot of current research is presented. This is a synopsis of "Air Quality in Barns" presented by Melissa R.Mazan, DVM, Diplomate ACVIM. After listening to this I wasn't sure I wanted to go back into a barn again.
Everyone knows that Barns are dusty places , this is no surprise. We don't design them for good airflow, in fact we build them more for protection and put walls up. Additionally, most barns are also used for hay and equipment storage. Not to be insulting but when was the last time you cleaned your barn? When an epidemiology study was done to evaluate respiratory disease among barn workers it was found that they had 50% more respiratory symptoms and grooms had a 3x incidence of asthma. Whereas significantly less symptoms were reported among Poultry, Swine and Dairy workers. In those environments there is more regulation and attention to cleanliness due to food production and the monitary costs associated with respiratory disease.
So what exactly is the problem, the problem is respirable organic particles or particlate matter.
The data suggests that > 2.4mg/cubic meter of air causes a higher morbidity. Most barns in this study had much higher levels than this , 40 to 60 mg/M3. In the breathing zone ( where the horses head is frequently low) it was higher. These particles include dust, endotoxin, mold spores, ammonia and arena dust(silica). Hay has 19.3 mg/M3 . Bedding is a prime source of particulate matter with straw being the worst and shaving somewhat better( but still bad).
When working in the arena the dust level reaches 60.6mg/M3 ....for both the horse and rider. The increased respiratory rate and volume allows for an even deeper penetration of particulate matter. This dust contains Iron, Copper, Magnesium and silica. Once in the distal airways this material functions as a foreign body causing marked inflammation. When these horse have their airways sampled using a BAL (Bronchial Alveolar Lavage) there is a massive increase in WBC's (White Blood Cells) . This inflammation is the principal cause of the clinical signs and can lead to chronic fibrosis if left untreated. So what do we know and what should we do?
1.The barn environment is unhealthy
2.Horse owners won't believe it.
3.If the horse has a respiratory problem....there's a good chance the owner may as well.

There are many different treatments out there but the best thing you can do is to keep your horse outside as much as possible. The second thing you can do is start cleaning. Move the hay to a separate barn or structure. Change the bedding. Pressure wash the whole place. Improve ventilation. Keep dust to a minimum. Feed hay outside....it is one of the prime offenders. Roll bales are worse since the horse has to stick it's head into the roll to feed.
If you are coughing , sneezing or have been complaining of respiratory illness..... then the barn might actually be the problem. It's time to start cleaning.