What Every Pet Parent Needs to Know About Heartworm
Unlike a broken bone or an open wound, heartworms do not advertise their presence with a limp or a whine. Because heartworm symptoms in dogs and cats are often invisible, internal damage can occur before a pet parent even notices any red flags. This is why heartworm prevention is one of the most important topics your veterinarian will ever discuss with you. The first step in protecting your pet from heartworm infection is to understand the parasite that causes it and where it comes from.
What Is Heartworm Disease?
Heartworms can only be transmitted from animal to animal by mosquitoes, the American Veterinary Medical Association explains. A mosquito bites an infected dog, picks up immature heartworms in the process, and then passes them along to the next dog it bites. Once inside a dog, those larvae take about six to seven months to grow into adult worms and settle into the heart and pulmonary arteries, where they can live for “five to seven years” (Cornell University College of Veterinary Medicine). The worms grow surprisingly large, and over time, the physical burden they place on the heart and lungs can become serious.
One of the most difficult realities for pet owners is that the early stages of heartworm disease are often completely silent. It can take several years before dogs show any visible signs of infection, and by the time a persistent cough or unusual symptom appears, the disease has already quietly progressed. Waiting for your pet to seem sick is not a safe approach and can be a risk to their long-term health.
What Are The Chances Of Infection?
Heartworm disease is more widespread than most pet owners realize, and the numbers are increasing every year. While many believe the risk is limited to humid, southern climates, Heartworm disease has been detected in all 50 states, and its reach continues to grow as climate shifts expand mosquito populations and the relocation of pets across state lines introduces the disease to new areas (American Veterinary Medical Association).
According to a recent American Heartworm Society (AHS) survey, data reported by the AVMA reveals that over 68% of dogs in the U.S. leave their veterinary clinic without a single dose of heartworm preventive. This gap in protection makes the "chance of infection" higher than ever. As the environmental and social factors evolve, the reach of this life-threatening disease continues to grow nationwide.
What Are The Signs of Heartworms?
Because heartworms damage the heart and lungs slowly over time, symptoms may be subtle at first. Early warning signs in dogs may include:
As the infection progresses, symptoms can become more severe. Dogs may develop difficulty breathing or a swollen belly due to fluid buildup. In the more advanced cases, an abundance of worms blocks blood flow through the heart, creating a life-threatening emergency that often requires immediate surgery.
Cats can also develop heartworm disease, although it affects them differently. Because cats typically harbor fewer worms, the disease may present as sudden respiratory distress, coughing, vomiting or asthma-like symptoms. In some cases, sudden death may be the first and only sign of infection. According to the American Heartworm Society, even a single worm can cause serious illness in cats.
What Treatment Looks Like (Why Prevention Is So Much Better)
If a dog tests positive for heartworm, serious treatment challenges lie ahead. An ingredient called Melarsomine dihydrochloride is the only FDA-approved drug for heartworm treatment in dogs, and it must be administered by a veterinarian through a series of injections (OVMA). Following treatment, dogs require restricted exercise for up to six weeks because active dogs are at risk for potentially fatal blood clots in the lungs. The process is physically taxing on the animal and emotionally exhausting for the family watching it happen.
Monthly preventive medications, chewable tablets, or topical treatments are accessible and highly effective. Heartworm preventives are safe, relatively inexpensive and easy to give, but if a dog becomes infected, treatment can be costly and difficult, requiring multiple veterinary visits and months of exercise restriction, the American Heartworm Society notes.
Protecting Your Pet Starts With Prevention
Heartworm is a serious and largely preventable disease. Because infections develop quietly and without symptoms, waiting until a pet appears sick can allow damage to occur inside the heart and lungs. Consistent preventive medication, screenings and regular veterinary checkups are the most reliable ways to protect pets from this dangerous parasite.
To support busy pet parents, Koala Health simplifies the prevention process. Through direct collaboration with veterinary clinics and veterinarians, Koala Health enables owners to easily order prescribed medications for their pets online, ensuring they are delivered directly to their homes on a regular schedule.