Tri-Heart Plus must be administered monthly, preferably on the same date each month. It is recommend for use year round. If only used during mosquito season, the first dose should be given within 30 days of the dog's first exposure to mosquitoes. The last dose must be given within 30 days after the dog's last exposure to mosquitoes.
Give Tri-Heart in a way that encourages your dog to chew the tablet, rather than swallow it whole.