Effectiveness of low dose immunotherapy in the treatment of canine atopic dermatitis: a prospective, double-blinded, clinical study.

There are anecdotal reports of increased effectiveness of allergen-specific immunotherapy (ASIT) in dogs with doses of vaccine lower than that recommended by the manufacturers. However, no controlled studies have been carried out. The aim of this prospective, double-blinded study was to evaluate whether induction and maintenance with low dose (LD) ASIT resulted in a different success rate compared with the standard dose (SD). Twenty-seven dogs with confirmed atopic dermatitis were allocated by block randomization to two groups. One group (n = 13) received SD ASIT; the other group (n = 14) received LD ASIT (1/10 of the SD) following the same frequency protocol. Cases were graded at 0, 3, 6 and 9 months for clinical signs using a modified canine atopic dermatitis extent and severity index (mCADESI) and for pruritus using a 0-5 descriptor scale. There were no significant differences between the groups in the pruritus and mCADESI scores (P > 0.155) at the end of the study, and the changes in pruritus (P > 0.920) and mCADESI (P > 0.296) scores from the beginning to the end of the study were similar in both groups. Pruritus scores in both groups did not change during the study (P > 0.052). However, significant reductions in mCADESI scores were seen in both groups (P < 0.032). Six dogs achieved a final pruritus score of 0, six achieved a reduction in pruritus score and 15 did not improve or worsened. There was, therefore, no evidence that LD ASIT is more effective than the standard protocol.