Heartworm Disease

Heartworm disease is a parasitic disease that affects primarily dogs, but can affect cats and ferrets. It can also affect wild animals such as foxes, wolves, and coyotes. Heartworm disease can cause serious health problems, and may eventually lead to heart failure and death if left untreated.

Mosquitoes transmit heartworms from animal to animal. The life cycle of a heartworm begins when a mosquito bites an infected dog with heartworm. The mosquito takes in tiny immature heartworms called microfilariae when it feeds. Over the next 2-3 weeks, the microfilariae develop into larvae. The mosquito can transmit these larvae when it feeds on a healthy dog. The larvae move through the animal’s body as they mature and eventually enter the heart and blood vessels. Over the next several months the heartworms reach adult size. Heartworms can grow up to 14 inches in length and may survive for up to seven years in dogs.

Heartworms are a potential threat in every state, as well as in many other countries around the world. All dogs, regardless of breed, age, sex, or living environment are susceptible to heartworm infection.

If your dog has been recently or is mildly infected with heartworm, it may show no signs of the disease. As the disease develops, your dog may cough, have difficulty breathing, become lethargic, or lose its appetite. If an animal is left untreated, it may eventually lead to heart failure and death.

It is recommended to test your dog annually for heartworm disease in the spring or prior to mosquito season. A simple blood test can be performed to test for the presence of heartworms. If your dog tests positive for heartworm disease, further tests may be necessary to determine the severity of the infection. Treatment for adult Heartworm disease is risky and requires hospitalization. In extremely severe cases some dogs may require surgery. Once your veterinarian determines that your dog is heartworm negative, you can begin giving one of the many FDA-approved preventatives available. Heartworm preventive should be given every thirty days after mosquitoes have an opportunity to infect your dog. Monthly preventive medication is usually needed in our area from May to October. It is important to follow your veterinarian’s instructions with all medications. As of January 2005 it became our clinic’s policy to require heartworm tests for all canine patients once a year before heartworm preventive medication will be dispensed. 

The reasons for this are multiple and as follows:
  1. We continue to see positive cases of heartworm disease, and our desire is to control and decrease the spread of this serious infection. 
  2. All heartworm preventative medications can cause serious adverse side effects, including death, if given to an animal that has an active heartworm infection. 
  3. Owner compliance with administering heartworm preventative is very good, but with our busy lives it’s not infallible. 
  4. The manufacturer will not guarantee the product efficacy without a yearly heartworm test. 
  5. We desire to practice medicine of the highest quality, which includes testing before dispensing medication. 

We care about you and your pet. If you have any questions about heartworm disease or would like to schedule an appointment for your dog’s heartworm test, please call us at 608-647-8944. We are always happy to answer any questions for you.