Most of the hunts I've known tend to have them put to sleep around 7 years old. Probably too early for most of these hounds to show up any problems which may occur in old age like other dogs.
Have one speyed Staffie (Bella). Vet advised her to be speyed as she had demodectic (sp) mange which was worse when she had her first season, as we never intended breeding from her it wasnt a problem. Touch wood had no more problems with the mange since and she will be 5 next March.
Also had a dog previously that had mammory tumours and had to be pts, not a pleasant thing to go through for either dog or owner.