A 3-year old male castrated Cocker Spaniel dog was referred to the Cornell University Hospital for Animals (CUHA) Emergency Service on May 31st, 2011, for presumptive congestive heart failure. At home, the patient was fed a vegan diet. Initial assessment revealed tachycardia, a grade II-III/VI heart murmur and increased lung sounds bilaterally. Thoracic radiographs revealed changes consistent with congestive heart failure. An echocardiogram demonstrated dilated cardiomyopathy. Blood taurine and carnitine levels were measured and both were low. A dose of furosemide was administered IV and oxygen therapy was initiated. The patient was started on pimobendan, enalapril, carnitine and taurine as well as a CRI of furosemide. He was switched to a commercial canine diet. He continued to improve with treatment and he was discharged to the care of his owner two days later. Follow-up echocardiograms revealed continued improvement in systolic function but the patient is still being maintained on his cardiac medications as well as supplementation with taurine and carnitine. Using the above case as an example, the pathophysiology of dilated cardiomyopathy with a focus on taurine and carnitine deficiency will be discussed.