Jeff

Jeff is the elderly pet dog of Ket in Kiki's Delivery Service.

Jeff first appears asleep on the carpet in Ketto's home until he wakes up and notices Jiji posing as Ket's stuffed cat toy while Kiki is out trying to retrieve the actual toy. Jeff thankfully does not harm the increasingly nervous Jiji and keeps him safe until Kiki returns at which point Jeff returns Jiji to his mistress and takes the actual toy in his place.

Studio Ghibli Wiki