A 1.5 year old male castrated Bennett's wallaby (Macropus rufrogriseus) presented for a 1 week history of aggression and progressive inappetance. Prior ineffective treatment by the rDVM included 1 dose of injectable penicillin and an olive oil/baking soda laxative. On presentation, the patient was mildly febrile, tachycardic, tachypneic and severely stressed, with a firm tubular structure palpated in the dorsal abdomen. Differential diagnoses included gastrointestinal obstruction, lead toxicity, enteritis, gastric ulceration and toxoplasmosis. Multiple diagnostic tests led to a presumptive diagnosis of toxoplasmosis, which was treated with TMS and supportive care. Despite treatment, the wallaby died and a necropsy was performed. Immunohistochemistry confirmed a diagnosis of severe disseminated toxoplasmosis. Macropods are extremely susceptible to toxoplasmosis. Common clinial signs include peracute death, blindness, ataxia, diarrhea and myositis. Diagnosis and treatment are challenging. Prevention is important and includes environmental control, stress avoidance and proper husbandry practices, including a high-fiber diet.