To coin a phrase

[Tuvok]

The answer includes an animal


person with an obsession about something



I'm thinking of the proverb/saying

Like a terrier with......


But I can't remember it?


Or if there are any other suggestions....

[factor-fiction]

like a dog with a bone

[ubasses]

a bone

[shaneystar2]

Like a dog with a bone

[vegasmad]

like a dog with a bone?

[Tuvok]

Maybe the terrier one I'm thinking about is a local variation of dog with a bone - whic I'll use if I can't remember the terrier one.

[sir.prize]

Like a terrier with a rat

See here and scroll down to item 17

http://www.thefreedictionary.com/persistence

[furrypusscat]

Nothing to do with dogs but if you are looking for other sayings - Like a duck to water.