Could you qualify this. I've never heard it before and would hate to be doing the dog harm. I thought that springer spaniels were bread for all day work
Really? You've never heard that!? Ask any decent vet, they will tell you the same. I'm a dog owner, my mother is a veterinary nurse and dog trainer, so I'm pretty confident with my answer. As said in my previous post, one bit of proof is the dog that crabs everywhere because the owner always cycled with it, although this was from a puppy while it was still forming its bones/muscles.
Some springers are breed to work all day, but the type of work they do is completely different to running for 20 miles. They are usually used for beating, which means going through horrible bushes & woods to flush out the Pheasants. Our dog can go beating all day, then get up the next day and do it again. Take her for a walk, and a couple of hours is enough, running is a lot harder than sniffing the ground and pushing through bushes. Although when she comes back she's got cuts, thorns and all sorts, but its a different type of work to running.
Our spaniel will easily do 15-20 mile run/ride, although I havent tried; but its the damage it will do later in life, early arthritus, back/hip problems etc.