This packet can be used on Dogs 4.6 - 9 kg and Cats 2.8 - 5.4kg.
 
Comfortis is available for dogs and cats, starts killing fleas before they lay eggs and provides a full month of flea protection to help prevent future flea infestations." 
Is very easy to administer!  
A flavored tablet is administered orally, so no residue, no worries about washing off after swimming, bathing, or grooming.