turps

http://www.neopaws.com/shoes.html
http://www.seniorpetproducts.com/index.php?p=catalog&parent=253&pg=0

or UK sites

http://www.canine-spirit.com/shop/detail.asp?prodid=15&prodsecid=3
http://www.culpeppers.co.uk/catalogue/?cat=booties are manufactuers - could be worth an email?
http://www.petplanet.co.uk/category.asp?dept_id=123

I'm more used to them for horses, but it's probably harder on dogs, as there's less of a clear joint line to secure above. Velcro or tape - something *flat* might be better than string type fastenings, to spread the pressure on his leg. Try and avoid too many crease points poking him in the leg by smoothing it into layered folds? Maybe fleece fabris with a parch of vinyl or something hard wearing bonda-webbed to the foot [not stitched, cos that could run inside]