Heartworm is a serious and life-threatening disease that affects dogs. It’s caused by a parasitic type of roundworm known as Dirofilaria immitis, which can live in the heart, lungs, and blood vessels of infected dogs. If left untreated, the worms can cause serious medical complications, including heart and lung damage, organ failure, and even loss of life.  

Heartworm disease in dogs is a progressive condition, meaning it worsens over time. At first, dogs show few or no symptoms, but as the worms grow and multiply, they can obstruct blood flow causing blood clots and damage to vital organs. 

Heartworm is spread to dogs through the bite of an infected mosquito. (It only takes one!) These mosquitos carry heartworm larvae, which enter the dog’s bloodstream when the mosquito bites. 

The life cycle of heartworm begins when a mosquito bites an infected animal and ingests something called microfilariae (baby heartworms) present in the blood. These microfilariae develop into infective larvae within the mosquito over about two weeks. When the mosquito bites another dog, the infective larvae are transmitted and begin their journey to the heart and lungs. 

The most common symptoms of heartworm in dogs can include: 

As the disease progresses, symptoms can become more severe. In advanced cases, dogs may experience heart failure, fluid accumulation in the abdomen, and fainting. If left untreated, heartworm can cause permanent damage to the heart and lungs, leading to heart failure.  If your dog is not currently on year-round heartworm prevention, it is essential that they be tested for heartworm as soon as possible by your local veterinarian. Catching the infection early provides a greater chance of successful treatment with fewer long-term health consequences. The American Heartworm Society recommends annual testing to ensure your dog remains heartworm-free. 

Did you know that heartworm-carrying mosquitos are found in all 50 states? So no matter where you live, it is important to take steps to protect your dog. There are several heartworm prevention options available, including monthly oral medications or annual injections. We suggest discussing these options with your veterinarian to determine which product best suits your pet and your own lifestyle. 

Preventive medications work by killing the heartworm larvae before they can mature into adult worms. These medications are typically administered monthly and come in various forms, such as chewable tablets, topical treatments, and injections. Some popular brands include Simparica Trio, Heartgard, Interceptor, and Revolution. 

If you live in or frequent an area where mosquitoes are more common (e.g., by a lake, pond, or river), increase your dog’s protection even more by using a dog mosquito repellent and keeping your dog up to date on heartworm medication. Mosquito repellents designed for dogs can help reduce bite risk but should be used with heartworm preventatives for maximum protection. 

No matter which medication you choose, ensuring your dog is consistently protected year-round is key—yes, even in the winter! Mosquitoes can survive in warmer indoor environments, and heartworm prevention should not be neglected during colder months. Set a reminder, buy in bulk, and/or set up Autoship through your vet’s pharmacy to help keep your dog up to date.  

Treatment for heartworm in dogs can take several months to complete, depending on how early the disease is caught. This treatment typically requires a series of injections and oral medications but may involve more extensive care, like hospitalization, breathing support, and/or surgical intervention, if the damage inflicted by the parasites is more severe.  

In severe cases, where the number of worms is high, a condition called caval syndrome can occur. This life-threatening condition requires immediate surgical removal of the adult worms from the dog's heart to prevent sudden death. 

The standard treatment involves administering a series of injections to kill the adult heartworms. These injections contain a medication called melarsomine, which is effective but can be harsh on the dog's system. In addition to the injections, dogs may receive antibiotics to eliminate any secondary bacterial infections and steroids to reduce inflammation. 

While we are thankful that heartworm treatment is available for dogs, the process can be expensive and may not undo long-term respiratory damage, depending on how early the disease is caught. When it comes to heartworm in dogs, prevention through year-round preventive medication is strongly recommended. 

Regular veterinary checkups are essential for maintaining your dog's health and preventing heartworm disease. During these visits, your vet can perform heartworm tests to ensure your dog is free from infection. Annual blood tests are recommended even if your dog is on preventive medication, as no preventative is 100% effective. 

In addition to heartworm testing, your vet can provide guidance on the best preventive measures for your dog based on their lifestyle and risk factors. They can also monitor your dog's overall health and catch any potential issues early, ensuring your beloved pet stays happy and healthy. 

No matter which state you live in, heartworm disease is a serious threat to dogs. But with proper prevention and early detection, it can be managed effectively. By understanding the risks, symptoms, and treatment options, pet owners can take proactive steps to protect their beloved pets from this dangerous parasite. 

Remember, prevention is always better than treatment. Keep your dog on year-round heartworm preventive medication, use mosquito repellents, and schedule regular vet visits to ensure your dog remains heartworm-free. Your pet deserves the best care, and with these measures, you can help them live a longer, healthier, and happier life.