When you take a puppy for its last puppy booster shot and its rabies shot then they will start you on heartworm preventative and do not have to test for heartworms b/c they are too young to have developed them yet. However, if you have an older puppy or an adult furbaby that has never been on heartworm preventative then you need to have a heartworm test done first to be sure he/she does not have heartworms. I do not think it will hurt your baby if you give them the preventative but if he/she does have heartworms then it wont make them go away...thats why you need to have a test done so if they have them they can start treatment to hopefully get rid of them b/c they will need treatment not a preventative. Hope this helps! |