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Examining Heartworm Medication for Dogs

Apr 26, 2017 04:27PM ● By Elisa Katz
























Most veterinarians recommend monthly heartworm preventive treatment for dogs as standard practice. However, due to the life cycle of the heartworm, a dog can actually achieve the same level of protection if the preventive is given every six weeks. This means less prophylactic drug for the pet’s liver to detoxify and less money spent, too.

       The heartworm lifecycle begins with the mosquito biting an infected animal (not necessarily a dog) and ingesting the L1 larvae. Over 10 to 14 days inside the mosquito, the L1 matures to an L2 stage, and then to an L3. If the L3 infected mosquito bites a dog, it will then become infected.

       This is where the preventives are effective, because they kill L3 and L4 larval stages. The maturation of L3 to L5 takes 45 to 60 days. For this reason, giving heartworm preventive can be done every six weeks (42 days) and still be effective.

Dr. Elisa Katz, DVM, CVA, CCRT, is the owner of the Natural Pet Animal Hospital, 711 Almar Pkwy., in Bourbonnais, IL. For more information, call 815-929-9393 or visit


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