I have a 16 year old border collie who's losing/lost control of his back legs. Other than that, he's pretty healthy. I've been looking at doggie wheelchairs online, and was wondering if anyone had any advice on particular brands, where to get cheaper ones/used ones (the prices seem to range from mid $100's to $400's), and any general experience with doggie wheelchairs.
I was advised I should put him down, but he's not in pain as far as I can tell and I see no reason to do that.
Any help would be most welcome. Thanks.

