Dexter's Laboratory (1996)
S02E20 Fantastic Boyage
Episode Overview
Dexter attempts to inject himself into Dee Dee to discover a remedy for the common cold, but accidentally gets transported into his dog instead. Convinced that Dee Dee has contracted a canine virus, he panics. When they visit the vet, Dexter is misidentified as the first human virus to ever infect a dog, adding to the chaos of the situation.