[kjc]

Originally Posted by Nancy1999

Please be very careful if you do this and check with your vet. The medication that Joey is given is very safe, and he could eat several in one month with no ill effects, in fact, some dogs have eaten a whole package without any ill effects. However, if you skip a month, and then forget to give another dose, you could be giving the next dose when heartworms have already gotten to the heart, and this would prove deadly to the dog.

It takes 6-8 months for a heartworm to grow to full size. L3's are readily killed by Interceptor but not by Heartgard30. Interceptor and Heartgard30 both act primarily on the L4's living in the skin (tissue stage= 2 months). After a dose of either medication, any L4's present will be wiped out. Heartgard30 is also able to kill the younger L5's. I believe that's another 2 months for migration to the heart, at which time they are still very small.