The life cycle of the larvae takes 90 days minimum to reach adulthood. The heartworm can not reproduce until adulthood. Most commercial preventative medicine is 95-100% effective at recommended doses.
Theoretically speaking, a single dose of meds every 90 days will stop any chance of larvae reproducing.
I suggest that you do your own research, and don't take my word for anything regarding the health of your dog. I'm not a vet.
I choose to treat with Ivermectin at a 10% elevated dose (over Heartguard) every 90 days from 1 March to 1 December. These dates are based on mosquito activity data for my current location. I also choose to use a product designed for another species. I have done my research and consulted with my veterinarian. I do this because I control the dose, because Fama was on this protocol because of potential allergies, and because it saves a considerable amount of money.
Any off label use of any product requires talking to the vet and deciding, with their help, what your acceptable courses of action are.
ETA: Heartworm is very serious. Treatment is lengthy and dangerous. Don't risk the health of your dog based on anything I say. I'm just some dude on the Internet. Talk to your vet before you make any decisions.
When a dog saves the life of a man, it becomes clear that partnership knows no bounds.
Fama - T.E.D.D. OEF XI-XII (GSD)(RET)
Marshall - T.E.D.D. OEF XII-XIII (Lab)(SF EDD)
Lucian - Med Alert / Mobility SD (Cane Corso)
Pud - the old man (Pit x Lab)
Last edited by David Winners; 08-05-2014 at 04:11 PM.