What are the risks if dog heartworm is left untreated?

The risks are pretty significant because if heartworm disease is left untreated and essentially unprevented, it's probably not going to end well for that dog. It may not be next week or next month, but at some point, that disease will rear its ugly head, and usually by the time it does, it’s not good. They basically die of heart failure.

If we don't treat that heartworm, as I said, it ultimately could cause the death of your dog. We obviously don't want that for your pet, and that's why we always recommend prevention.

If dog heartworm is left untreated, the heart will become enlarged due to the number of parasites in the heart. It can cause heart murmurs as well as potential death.

If heartworms are left untreated, they can cause heart failure, liver failure, and lung failure, as well as inflammation in the heart, lungs, and arteries, which can lead to other health issues.

The main risk is congestive heart failure leading to death.