Is it true that heartworm was previously believed to affect only cats, but has now been found to be fatal in dogs as well?

Heartworm disease is caused by a parasite known as Dirofilaria immitis, which primarily affects dogs, though it can also infect cats and other animals. Historically, the perception of heartworm was that it predominantly posed a risk to dogs. As research progressed, it became clear that while cats can become infected, the disease often manifests differently in them and is generally considered less common.

The current understanding is that heartworm can lead to severe health complications and can be fatal in dogs. It is not a condition that was originally thought to only affect cats; rather, it has been recognized as a serious threat to both species for quite some time. Therefore, the notion that heartworm previously only affected cats and became a more widespread concern in dogs is inaccurate. Dogs are indeed vulnerable to significant health issues resulting from heartworm infestations, and this has been known for many years.

This context clarifies that the idea presented in the statement misunderstands the established knowledge about heartworm disease and its impact on both cats and dogs. The correct response aligns with the current veterinary consensus regarding heartworm and its more serious consequences for canine health.