ABSTRACT
The effect of oral treatment with natural or recombinant human interferon alpha (HIA) on inflammatory airway disease in young standardbreds was assessed in a double-blind, randomized clinical trial. A total of 34 horses with nasal discharge, excess mucus in the trachea, and a persistent cough of at least 2 weeks' duration that interfered with training completed the trial. Horses were rested for 1 week and received oral treatment with either a saline placebo, recombinant human interferon alpha (rHIA; 90 U/horse/day), or natural human interferon alpha (nHIA: 50 U/horse/day) for 5 days. There was a significant decline in nasal discharge and cough scores in all groups and the apparent response rate was similar. However, significantly fewer horses relapsed within 2 weeks once treatment was ceased when interferon rather than placebo was used (P = 0.012). Seventeen of 22 horses treated with rHIA or nHIA were cough-free 4 weeks after treatment, compared with only 4 of 12 after treatment with the placebo. Treatment with oral interferon is a useful adjunct to rest in standardbreds with inflammatory airway disease.
