Dog missed monthly Sentinel dose, should I give Sentinel again?

Yesterday it came to my attention thamMy dog may not have gotten the dose of sentinnel he was supposed to take 8/8/07 but I can't be sure. Is it better to wait or give him another dose? Could there be negative effects from giving him 2 doses in one month?

Hello, it would be better to give him another dose now to make sure he is protected, also since its been almost three weeks already there should be no problem with another dose of Sentinel. Missing one dose should not be a problem because most heartworm medications have a reach back effect of 30 days. Please talk about this with your vet, the next time you buy Sentinel for your dog.

Thanks,

Dr. Chris