A 6 year-old, male neutered Golden Retriever presented to his local veterinarian with a four day history of lethargy, anorexia, and a weight loss of 18 pounds over the past three months. Upon examination, the dog was quiet, but alert and responsive. Initial evaluation disclosed pale mucous membranes, a CRT < 2 seconds, jaundice of the sclera and gums, and a temperature of 104.3°F. After being admitted to the hospital, initial laboratory tests were performed and the following abnormalities were detected: a hematocrit of 22.4% (ref 37-55), severe normochromic macrocytic anemia, mild neutrophilia, spherocytosis, polychromasia, anisocytosis, mild hyperbilirubinemia (1.1 mg/dL), and a mildly low T4 of 1.1 µg/dl. The slide agglutination test was negative. The dog was then treated with prednisone, amoxicillin, famotidine, and azathioprine, as well as blood transfusion the following day. This case report will discuss a primary clinician’s diagnostic workup of an anemic patient, differential diagnosis for regenerative anemia, laboratory data, treatment, and outcomes of dogs with immune-mediated hemolytic anemia.