Missing a dose here and there might seem harmless, but heartworm prevention works best when it's consistent. When dogs go without protection, they're vulnerable to infection from mosquito bites. The longer the gap, the higher the risk that heartworm larvae can mature into adult worms that settle in the heart and lungs.
• Heartworm prevention stops larvae before they mature into adult worms that damage the heart and lungs
• Missing doses creates windows where mosquitoes can transmit infection that develops over months
• Treatment for established heartworm disease is expensive, requires strict rest, and carries more risk than prevention
• Even one missed dose during mosquito season can leave your dog exposed
When an infected mosquito bites your dog, it deposits microscopic heartworm larvae into the skin. These larvae need about six months to grow into adult worms. Monthly preventives kill these larvae during their early stages, before they can cause problems.
Without prevention, the larvae continue developing. They migrate through tissue, eventually reaching the heart and pulmonary arteries. Adult heartworms can live for five to seven years, growing up to a foot long and reproducing inside your dog. The damage happens gradually as worms accumulate and interfere with blood flow.
Treating an active heartworm infection is a different situation than preventing one. The process involves multiple injections to kill adult worms, followed by weeks of strict exercise restriction. Your dog needs to stay calm because as the worms die, they break apart and travel through the bloodstream. Too much activity increases the risk of complications.
Treatment also costs significantly more than prevention. You're looking at diagnostic testing, hospitalization, medications, and follow up care. Some dogs experience serious reactions during treatment, and in severe cases where many worms are present, the risks increase.
Not every dog is a good candidate for treatment either. Dogs with advanced infections or other health conditions may face additional challenges. Prevention avoids all of this.
Dr. Perry and our veterinary team at Otis can help you stay on track with heartworm prevention. We offer online consultations to discuss the right preventive for your dog based on their health history and where you live. We can write prescriptions for monthly preventives and send reminders so you don't miss doses.
If you've missed doses or aren't sure about your dog's current status, we can guide you on next steps, including whether testing is needed before restarting prevention. Keeping your dog protected is simpler and safer than treating an infection after it develops.
