could anti flea/tick goo be too powerful for our dogs?

I'm new to this dark side of "recommended dosage for smaller dogs". So my verbiage on this subject is nothing more than 'sharing' what I soon found out I needed to learn.

I took almost 2 years of research to find a breed that was long lived, no inherited health issues and did not succumb easily to normal diseases.

I found what breed fit my requirements only to find out that "I" would most likely be the one to kill them by following the recommended dosage on the labels?! :S