Pravastatin (PS) has been found to increase left ventricle (LV) expansion capacity and decrease LV constriction and left atrial pressure in healthy dogs. To date, there are no available reports on the effects of PS in dogs with hypercholesterolemia with chronic heart failure (CHF). This case report demonstrates a successful long-term treatment plan using PS in a dog suffering from mitral insufficiency with hyperlipidemia. A 12-year-old, castrated male Chihuahua dog had mitral insufficiency with hyperlipidemia. The dog presented with symptoms of chronic coughing. PS was orally administered (1 mg/kg, SID) in addition to general treatment for mitral insufficiency. The follow-up period was 375 days. PS administration decreased the heart rate (HR), vertebral heart size (VHS), and N-terminal probrain natriuretic peptide (NT-proBNP) concentration of the dog. In addition, PS administration also improved chronic cardiac failure induced by mitral insufficiency and hyperlipidemia. This report suggests that PS can be useful as an adjunctive therapeutic for dogs with hypercholesterolemia with mitral insufficiency.