"What's truly frightening about heartworm disease? It can be silent but deadly," says Veterinary Economics Editorial Advisory Board member Dr. Andy Rollo, an associate at Madison Veterinary Hospital in Michigan. "It's vital to explain the symptoms and risks to clients in endemic areas."

He says respiratory issues are a common clinical symptom: some pets experience an occasional cough, while others have breathing difficulties that are very debilitating to their well-being. Heartworm disease can also be responsible for other internal problems related to the liver, kidneys, gastrointestinal tract, and even nervous system. Adult heartworms can cause sudden death in pets (especially cats) that haven't shown any symptoms. "If you've ever had a patient die from heartworm disease, I would share that story with pet owners who decline prevention," Dr. Rollo says. Explain that heartworm treatment for dogs with a heavy adult worm burden isn't a piece of cake.

"Unfortunately, the injections can be painful and the patient could have a severe reaction to the worm's death," Dr. Rollo says. "On top of that, there's no specific safe drug to kill adult heartworms in cats, further proving the importance of prevention for both dogs and cats."