An often ignored but extremely important disease of dogs in our area is heartworms. Old hat you say? Not so. Every veterinary hospital of which I am aware treats dogs with heartworms every year. Although many are rescues from the southern US, many are natives to the Northeastern US as well. It is a fatal disease causing manly slow onset heart failure, but may also cause lung and liver issues. It is virtually totally preventable, requires an expensive long term treatment, and may leave your dog with progressive heart disease after treatment.
One tiny mosquito can easily infect many dogs. Once the larvae are under the skin, they actually start an amazing migration towards your dog’s heart.
Heartworms is started when a heartworm carrying mosquito bites your dog. Inside the mosquito mouthparts are hundreds of “baby” (larvae) heartworms and they are introduced at the time of the bite. One tiny mosquito can easily infect many dogs. Once the larva are under the skin, they actually start an amazing migration towards your dog’s heart. During that migrations, which takes about 6 months, the larva changes form several times untl it burrows into the heart as an adult. There are typically scores of worms inside the heart. This puts tremendous strains on the heart, leading to disease and failure. Symptoms don’t start until many months after infection, so just because your dog has no symptoms does not mean he heartworm free.
Symptoms will vary from weight loss, coughing, panting, intolerance to exercise, and lethargy. Those symptoms can describe many diseases so an accurate diagnosis is essential. Diagnosis is made by an ANNUAL blood test, usually at the time of your dog’s annual physical exam. Test results are commonly available during the visit. If your dog’s test is negative, you can resume heartworm prevention. If your dog’s test is positive, your veterinarian will classify the disease from Class 1 through 4, 4 being the most severe. Treatment is based upon the Class ranking, as is the prognosis.
Treatment will vary with each patient. Radiographs of the heart and lungs are a must to evaluate any damage. Blood and urine tests will be run to look at major organ function. Medication may be given prior to killing the worms themselves in order to get your dog in the best condition to tolerate the hundreds of dying worms and the medication used to kill those worms. Treatment can take weeks to months. The cost of treatment depends upon the extent of treatment.
The take home message is clear to your veterinarian. Use year-round prevention in the form of oral treatment. Even though you give the medication regularly, the annual test will be run. The human “forgetting” syndrome, or any break in the medication can open your dog to infection. As for the prevention, when purchasing it through your pet’s doctor, there can be guarantees offered. Some drug manufacturers will pay for treatment if your dog becomes infected if you can prove that you purchased your medication from an animal hospital. Online purchases do not qualify.
Click on the infographic above to view the lifecycle of heartworms. From the moment a mosquito bites an infected dog, the larvae develops in the mosquito and becomes infective. When that mosquito bites your dog, the larvae travels to the dog’s tissue and further develops into adults. They migrate to the heart via the bloodstream and begin producing their own larvae.
Learn more about the disease and treatment at The American Heartworm Society.