Well if it is trifexis one thing to consider is the fleas will still bite and could past on a diease.
Guinness used to take trifexis till we switched vets and he explained he does not prescribe it due to the dog will still get dog bites and because it is a chemical that stays in your dogs system including of course liver and since Yorkie are already known for liver issues it was best for us to stop using it.
__________________ Alisha mommy to Guinness Stout 7 & Stella Artois 5 & Teagan 4    Guinness & Stella proud Teapot Club Members |