Hello,
I am a Vet Nurse and Ive just come across your question.
Im pretty sure what you have is Advantage if it is in a purple box. I would, if I was you, only use it on a Cat. If it is Advantage then this is purely for Fleas and nothing else where as Advocate covers for much more. If I were you I would purchase one specificly designed for Dogs. Talk to your closest Vet for further confirmation but Im pretty sure in what Im saying. For Cats the dosage would be very different than for dogs and most likely it wouldnt do its proper job.
Good luck and I hope ive been of some help to you!!
Mas