Q: We have a 12-year-old dog who has been really healthy for his whole life. At our recent check-up with our veterinarian, she said that he has a Grade 3 murmur in his heart. We were told that at this time he doesn’t need to take any medication for it, but we need to watch for any signs of problems such as coughing, etc. If he starts to show signs of heart disease we will begin treatment. My question is, shouldn’t we do something now to try to stop the murmur from getting worse, such as putting him on some type of heart medicine?
A: So your dog has been diagnosed with a heart murmur, which is probably disease of one of the heart valves, specifically the mitral valve on the left side of the heart. This is a very common disease of older dogs, especially in many of the small breeds. It is almost always an acquired disease, meaning that your dog wasn’t born with a heart valve defect, it has simply degenerated with time and age and is not functioning properly now.
Even though it may seem strange to not do anything yet, your veterinarian is correct in saying that it does no good to start medicating early, before clinical signs have started. Several studies have been completed that show that early medicating of dogs with mitral valve disease shows no improved heart function or ultimately an increased life span as opposed to those who begin treatment when clinical signs such as coughing and/or exercise intolerance begin to appear.
One thing that you didn’t mention is whether your veterinarian took any chest X-rays. This is important as we need to know whether the heart is starting to show any enlargement. The X-rays also are used to rule out other chest and/or lung disease that may be present.
For now, just follow your veterinarian’s directions and continue to monitor his heart condition with exams and X-rays as needed. Eventually, you will have to start medications, but there is no need to rush it.