I see enough dogs around to think that it won't be a problem. With the current rental market there are probably a lot of landlords who now allow pets just to get a tenant. You will be excluded from HDB though, large breeds aren't allowed.
There is a
property link at the top of the page and a google search will also reveal other sites.
Suggest you rent near a park. I'm on the East Coast and it's great for dogs, albeit on leash. I know of one dog walking park at West Coast Park, I imagine there are others.
Transporting a large dog should be a consideration, they aren't allowed on public transport. And if you are thinking of getting car, check the prices here first, they are stupidly steep.
