In today's VETgirl online veterinary continuing education podcast, we review liver toxicity secondary to azathioprine administration in dogs. Azathioprine is an immunosuppressive medication that has been gaining popularity in the veterinary community. It is a purine analog that can take up to 6 weeks to take effect (Plumb), and it is often used as a treatment for immune-mediated hemolytic anemia (IMHA), immune-mediated thrombocytopenia (ITP), immune-mediated polyarthritis, inflammatory bowel disease, and other immune-mediated conditions. Some practitioners express discomfort using azathioprine due to its potential for adverse effects, such as hepatotoxicity and bone marrow toxicity. But how worried should we be?