Trailhounds look similar to foxhounds but are leaner in build. Their originally were bred from foxhounds with other crosses to get a faster hound with a good nose. Probably various out-crosses were tried many years ago before the present type evolved. They are bred for stamina and speed. A 10 mile trail takes between 25 minutes and 40 minutes and typically covers all terrain, from low-lying pasture to steep fell sides with streams, walls and ditches to be crossed in-between.
I pressume you mean do Lakeland Trail hounds moult as in shed hair? I would think they would although from the trailhound I have at the moment his hair is very short and fine.
Depending on what breed the dog is, the filming over the eyes could be some sort of infection. But some dogs are born with it, for example: Bloodhounds, Foxhounds, Trailhounds, and many more working dogs etc. The filming over the working dog's eyes is for running through long grass and stuff, to chase foxes or other things, whatever the dog's purpose is. I have a Trailhound and occasionally I can sometimes see a green tint, it's his filming, he used to be a working dog. So yeah, it's either an infection in the eye or the instinctive filming for a working dog. If you're unsure, then the dog should probably go to a vet.