Why Heartworm Prevention is Important

Why Heartworm Prevention is Important

Heartworm disease is a serious disease that results in severe lung disease, heart failure and other organ damage and can cause death.  It is caused by a parasitic worm which is spread through the bite of a mosquito. 

The adults produce microfilariae, the earliest life stage that circulates within the dog’s blood.  Prevention kills only early stage larvae and microfilariae.  That is why it is important to give your dog heartworm prevention every month. It kills the larvae before they develop into a stage that is immune to the medication in heartworm preventatives. 

Monthly heartworm preventative medications don’t stay in your dog’s bloodstream for 30 days.  The active ingredients work to kill any larvae that have been in the system for the past 30 days, clearing the body each month.  The preventatives are only needed once a month because it takes longer than a month for the larvae to develop to a stage where they reach the body tissues.



Your vet will need to test for active infection of heartworms before giving a heartworm medication.  Dogs with heartworms can have a severe, possibly life-threatening reaction to the dying, circulating microfilariae if given heartworm medications.  Also, your vet wants to be certain that if you missed a dose or your dog may have spit the medication out with you being unaware of it, your dog will have been unprotected for a period of time.  

If you don’t test for the disease and your dog is infected, the disease will gradually progress and cause serious, life-threatening illness.

Your dog should be given heartworm prevention year round.

Dogs have been diagnosed with heartworm disease in every state in the US.

Monthly heartworm preventatives are safe and easy to give, but if they are skipped and a dog becomes infected, heartworm treatment can be costly and difficult, requiring multiple vet visits and months of exercise restriction.

There are drug-free strategies owners can put in place to reduce a pet’s exposure to mosquitoes but there is no such thing as a natural heartworm preventive.