Effect of prednisone on spontaneous canine asthma

This study was designed to investigate the effect of corticosteroids in spontaneous ragweed-sensitive asthmatic dogs. Two animals were treated with prednisone, 40 mg. daily for 3 weeks, and with gradually tapered doses for 6 weeks. The animals were challenged with an aerosol or ragweed extract (RW) before and at intervals during and after drug therapy, and their skin reactivity to the antigen was determined at the same time. The Prausnitz-Küstner (PK) titer and the amount of serum necessary to passively transfer ragweed anaphylaxis to nonatopic dogs were also determined at the same intervals. Treatment of the atopic dogs with corticosteroids completely prevented the ragweed-induced asthma during and for up to 3 months after cessation of therapy. Although the skin reactivity of the atopic dogs was depressed, the PK titer of the sera did not change appreciably during therapy. Increased amounts of serum, however, were necessary to passively sensitize nonatopic dogs for ragweed anaphylaxis for up to 7 months after cessation of drug therapy. The results of the study indicate that corticosteroids can abolish active and passive allergic responses in dogs for as long as 7 months after cessation of the drug, but the mechanism of action is not clear.