Asthma 
Asthma Asthma is an inflammatory condition of the airways leading into the lungs. The airways become inflamed and spasm, causing excessive amounts of clogging mucus to build up, which in turn sets off a contraction of surrounding muscles. Asthmatic flare-ups can cause extreme difficulty in breathing. This condition is seen more frequently in cats but also occurs in dogs. Airborne allergens are often involved in asthma.
I recommend an oral stabilized oxygen product for any lung or allergic condition. There are many available in health food stores. I use Earth Bounty Oxy-Max from Matrix Health Products (800-736-5609). This product oxygenates the whole body, including the lungs, and helps to clear out toxins generated by allergies.
You should see improved breathing within four to five days. Older pets, or animals who have been long-term on medication such as steroids for allergies, may take two weeks.
Dogs under twenty pounds, 3 drops; dogs up to forty pounds, 5 drops; dogs up to sixty pounds, 8 drops; larger dogs, 10 drops. Add drops to food. Apply twice daily if condition is severe.