I don't know any substitutes but my grandma used to put her dog's medicine either in a lump of Braunschweiger (her dog LOVED the stuff) or if that wouldn't work she'd put it in butter and force it into the back of his mouth. The butter would help it to slide down without much assistance needed.
Perhaps on of these will work?
Yinzer, Hills SD Prescription is a dog food only available on Prescription from vets. What is Braunschweiger - is it a sort of sausage.
Nirvana, I don't know whether your dog has the dried or tinned version of Hills. Have you tried both.
I have got round this problem by adding about a tablespoon of their usual food, putting in some water, mixing it well and heating it in the microwave until it is just warm. May be worth a try.