If you give the monthly heartworm tablet one day late, does it screw up the entire process?

The vet's office I take my puppy to sells me Hartgard monthly. I give it to her on the first of the month. Would it screw up the process if I give it to her one day late?

Nope. As long as you're within a day or so you're OK.Some months have 30 days, some 31 right?

No. One day doesn't make that much difference.Otherwise things would get really complicated, since some months have 30 days, some have 31, and February has either 28 or 29.Go ahead and give your dog her heartworm pill.

No. What it does is kill off any heart worms before they get mature enough cause problems. So they are up to 32 days instead of 31.

A heartworm pill doesn't actually stay in the dogs system for the entire month, rather it works for a short period. Goes through your dogs system and kills any heartworm that may have entered the bloodstream that month. So really as long as you do it within 4 months, your dog will be fine. The veterinarian I worked for would only retest a dog if they were off their heartworm preventative for longer then 4 months because that is around how long it takes for the worm to mature and start causing damage to the heart, meaning you don't want it to die abruptly and cause the dog to go in to shock.