Heartworm Prevention

Heartworm infeciton has caused heart failure in the dog on the right. Notice the large heart and the white areas in the lungs. This dog was treated for heartworm disease but will always have heart failure.

Heartworm disease is a serious disease that affects both cats and dogs. Heartworms are worms in the blood that are transmitted by mosquitoes. The mosquito bites your pet and injects an immature heartworm. When your pet is not on preventive medicine, the worm matures and makes its way to the heart and lungs. Here, it causes damage leading to heart failure and even death. Cats usually have lung damage instead of heart damage and sudden death is a possibility. Luckily, we have medicine that can prevent the disease when given regularly. 


Toby has been on heartworm prevention since 9 weeks old.

For dogs less than 6 months old: 

It takes 6 months for the worm to develop to the stage that shows up on our test. Therefore, a heartworm test does not need to be performed. Your puppy should be placed on heartworm prevention as soon as possible which is as early as 6 weeks. 

Scooby waits for his "treat".

For dogs over 6 months old: 

A heartworm test should be performed every 12 months to ensure that they do not already have heartworms. If the test is negative, your dog should continue on heartworm prevention year round. If your dog tests positive, further testing will need to be done so correct treatment can be given. 

Kristina gets heartworm and flea prevention together every month.

For all cats: 

Heartworm tests are not reliable in cats so they don't need annual testing. Therefore, all cats should be on heartworm prevention year round.The best option is usually a topical (on the skin) medicine that prevents both fleas and heartworms.