It can happen to any of us. What to do if you miss a dose of your dogs heartworm preventive?
If you miss one month. Give a dose right away and continue with the new date from that point forward.
If you miss two months, start up right away and consider giving the antibiotic Doxycycline for one month.
If you miss 7 or more months, get a heartworm test done and then get back on a monthly schedule.
If you EVER have any questions or concerns, Please call you Vet.