Heartworms are blood parasites of dogs and cats. They are spread by mosquitoes, and they can cause heart failure. Veterinary parasitologists, who are the experts on the subject of heartworms, have been sounding alarm bells about the worms for several years. They worry that heartworm disease is a growing threat to pets. And some experts believe that many vets are not treating young animals with heartworm preventatives appropriately.
Most vets recommend starting heartworm preventatives at four to six months of age. But an online discussion forum that occurred through the Veterinary Information Network (VIN) on October 5 challenged this mantra.
Dr. Tom Nelson, moderator of the forum, pointed out that two months of age (or perhaps earlier) is a more appropriate time to begin heartworm prevention. His argument was based on features of the heartworm life cycle and the means by which preventatives protect pets.
I won’t bore you with all of the details. But I am going to change my recommendations for heartworm prevention in young animals.