Last year our puppy Belle was diagnosed with dilated cardiomyopathy. She was on digoxin and several other medications. The cardiologist suggested we use 1 gram of L-carnitine two times a day, 250 mg of taurine two times a day, and 25 mg of co-Q 10 three times a day. She said these supplements would help to strengthen her heart. Belle was a very sick puppy so I don't know if these dosages were because she was so sick or if any dog with a heart problem would use the same dosages. Your vet should probably be able to confirm the proper dosages.