Low-dose oral administration of interferon-alpha for the treatment of immune-mediated keratoconjunctivitis sicca in dogs

This preliminary study was designed to evaluate the effectiveness and dosag e of oral use of interferon-alpha (IFN-alpha) in the treatment of naturally occurring, immune-mediated, canine keratoconjunctivitis sicca (KCS). Dogs with chronic immune-mediated KCS were selected from the two clinic populati ons. All medication, except topical artificial tears, was discontinued at l east 2 weeks prior to beginning the clinical trial. IFN-alpha was administe red orally once daily to the dogs by their owners as the sole therapy for t he KCS, Examinations of the dogs were performed every 2 weeks for the durat ion of the trial (12 weeks). Each dog was given either two or three separat e, escalating doses (20, 40, 80 IU of the IFN-alpha. A favorable response w as observed in 55% (11/20) of all dogs treated, Clinical findings of those dogs that responded included increased wetting of the eyes, decreased mucus discharge, and fewer signs of discomfort, There was a nearly significant d ifference (p = 0.08) in pretreatment mean Schirmer's tear test (STT) betwee n the dogs that responded (6.4 +/- SEM 0.62 mm/min) and those that did not respond (4.7 +/- SEM 0.69 mm/min) to the orally administered IFN-alpha. Sev en of 11 dogs with favorable outcomes had an increased STT of at least 5 mm /min after treatment with oral IFN-alpha and the group had a post-treatment STT (10.5 +/- SEM 1.4 mm/min) significantly greater than baseline (p = 0.0 004), The post-treatment STT of the dogs that did respond was significantly greater (p < 0.01) than the post-treatment mean STT of dogs that did not r espond. All dogs that responded did so with the 20 or 40 IU dose of IFN-alp ha. No side effects were noted and all dogs tolerated the treatment well.