"Destrier" for horse. :) Technically it's the kind of horse used for combat -- the term was originally French, but was also a part of English during the middle ages (iirc).

There's "moggy" for cat, though that's still used in parts of the UK and Australia.

Gleek -- the little involuntary spit that flies out of your salivary glands while your mouth is open.

"Woobie" is an obscure-in-the-USA term in English for a soft "security blanket" or other soft thing that little kids become attached to. I think.