A four year old female spayed Shih Tzu was presented to Cornell's Emergency and Critical Care service for acute onset trembling and abnormal behavior. Her signs were determined to be secondary to ingestion of cookies containing marijuana. She was hospitalized and treated with intravenous fluids, activated charcoal and intravenous lipids. The patient was severely affected and developed respiratory depression which has not previously been reported in marijuana toxicosis. Supplemental oxygen was required. She made a full recovery and was discharged from the hospital two days later. Canine marijuana ingestion is being encountered with increasing frequency in veterinary practice. This case report highlights the mechanisms and signs of marijuana toxicosis and discusses treatment options and prognosis.