Interceptor is designed to be administered once every 30 days. The manufacturer recommends starting it within 30 days of mosquito exposure and continuing through the rest of mosquito “season.”
However, it is important to note that in many regions, mosquito-borne heartworm disease is a year round concern, leading most veterinarians to recommend using prevention every month all year.
If a dose is missed within 30 days of its due date, the manufacturer recommends giving the next dose as soon as possible. If it has been beyond 30 days of the last due date, the manufacturer recommends re-evaluating a cat for possible heartworm disease first through blood testing and evaluation of any clinical signs by a licensed veterinarian.