The purpose of this proposal is to provide funding to confirm the efficacy and safety of T-cell receptor (TCR) peptide treatment in dogs with non-responsive atopic dermatitis. Atopic dermatitis is a frustrating, chronically relapsing allergic skin disease in dogs. Treatment options are limited; many dogs require prolonged administration of steroids or other drugs. The only specific cure is skin testing and desensitization treatments over prolonged periods of time, managed by skilled veterinarians. Palliative treatments and newer immunosuppressive drugs such as cyclosporine are effective under carefully managed conditions. It is now known that the underlying cause of atopic dermatitis in dogs is impaired immune responsiveness, specifically T-cell imbalance. In laboratory mice, TCR peptide treatment consistently rebalances T-cells and restores normal immunity. In dogs with atopic dermatitis, previous AKC sponsored studies showed that TCR peptide treatment resulted in long lasting (60-90 days) improvement in itchiness and other signs of atopy, consistent with restoration of normal immune responsiveness. Furthermore, dogs with atopic dermatitis were found to have 16 fold higher anti-TCR antibody activity compared to normal dogs, suggesting new diagnostic tests. The objective of research described in this proposal is to complete clinical trials to verify the efficacy and safety of TCR peptide treatment in dogs with atopic dermatitis. Laboratory tests will also be conducted on serum samples from these dogs to confirm the immunological effects of TCR peptide treatment and to develop new diagnostic tests for the disease.