Anti-thymocyte serum as part of an immunosuppressive regimen in treating haematological immune-mediated diseases in dogs.

OBJECTIVES: To report the outcomes associated with the use of rabbit anti-dog thymocyte serum in dogs with haematological immune-mediated diseases. METHODS: Medical records from 2000 to 2016 of patients diagnosed with immune-mediated haemolytic anaemia, immune-mediated thrombocytopenia, pancytopenia and myelofibrosis were reviewed. All dogs had a severe or refractory disease and received rabbit anti-dog thymocyte serum. Lymphocyte counts were used to monitor the immediate anti-thymocyte effect of therapy; long-term patient outcome was recorded. RESULTS: A total of 10 dogs were included. All dogs except one had a notable decrease in their lymphocyte count after rabbit anti-dog thymocyte serum; four of nine had a decrease to less than 10% of the initial lymphocyte count and one dog reached 10·8%. All dogs were discharged from the hospital following their treatment. The dog with no alteration of lymphocyte count following therapy with rabbit anti-dog thymocyte serum had refractory immune mediated haemolytic anemia and was euthanised within two weeks. All other cases achieved clinical remission with immunosuppressive therapy eventually being tapered (3 of 10) or discontinued (6 of 10). CLINICAL SIGNIFICANCE: Rabbit anti-dog thymocyte serum therapy might be of interest as an adjunctive therapy in refractory immune-mediated diseases and suppressed lymphocyte counts in most dogs.