Maccy's would have there own suppliers who make it for them. You could buy sausage meat and make them yourself, or if their is a particular sausage you like, then remove the skin and form into patties
Macci's meat comes from their invesment in Russian farms - its how they effect their foreign exchange - grow meat in Russia, export it for forex and use that to counter the roubles they generate in their retail stores, all tax minimised as well.
congrats on the new puppy, are you calling him Banger?
I would call mine "Useless" after the spaniel in Monarch of the Glen - I think its a brill name for a dog and especially as folk will think you are shouting Eustace when calling out loud for the dog.