A 1-year-old spayed female Goldendoodle was presented to Cornell University Hospital for Animals’ (CUHA) Emergency Service for evaluation of progressive weakness, regurgitation, and aspiration pneumonia following a 10-day history of regurgitation and weakness. General physical exam revealed increased lung sounds on the left, and neurological exam revealed tetraparesis, fatiguing palpebral reflexes, and weak patellar and withdrawal reflexes. Thoracic radiographs confirmed megaesophagus with secondary aspiration pneumonia. A Tensilon® test was positive and the patient was started on pyridostigmine for presumptive myasthenia gravis. A nasogastric tube was placed to facilitate feeding. She was hospitalized for 7 days on intravenous antibiotics and supportive care for her aspiration pneumonia and had a positive response to treatment. An acetylcholine receptor antibody test (AChR-Ab) test was initially negative, but positive when retested 3 months after onset of clinical signs. This paper will discuss the workup, treatment, and long-term management of myasthenia gravis and aspiration pneumonia in our patient.