An Australian cattle dog (case 1: 6-year-old castrated male) and a Shih-Tzu dog (case 2: 8-year-old castrated male) were referred to the Gyeongsang Animal Medical Center due to anorexia and depression. Physical examinations, complete blood counts, serum chemical analysis, radiography, ultrasonography, and bone marrow biopsy were performed. Upon physical examinations of cases 1 and 2, enlargement of superficial lymph nodes was not identified. Hematologic findings in these dogs included leukocytosis with severe lymphocytosis, anemia, and thrombocytopenia. Upon radiography, both dogs showed splenomegaly. Upon examination of a peripheral blood smear in case 1, immature lymphoid cells, featuring decreased nuclear chromatin condensation and nuclear pleomorphism, were present. Biopsy samples of the bone marrow in case 1 revealed hypercellularity as well as a large number of immature lymphoblastic cells similar in shape to cells in the peripheral blood. The characteristic morphological features of peripheral blood and bone marrow samples in case 2 were small lymphocytes. Thus, the dogs were tentatively diagnosed with acute lymphoblastic leukemia (ALL) and chronic lymphocytic leukemia (CLL), respectively. After diagnosis, the CLL patient was administered chlorambucil and prednisolone therapy. Due to its similarity to human leukemia, the canine leukemia model provides a valuable model for research into human leukemia.

• Hae-Won Jung(Institute of Animal Medicine, College of Veterinary Medicine, Gyeongsang National University)
• Dong-In Jung(Institute of Animal Medicine, College of Veterinary Medicine, Gyeongsang National University) Corresponding author