Try spaniels, most will disagree but I have worked spaniels with the ferrets in the undergrowth whilst hunting and have never had a problem. Although thats me, I love spaniels

. As said try to avoid hounds and terriers as these are made to hunt small animals anyway. Also my new Viszla bitch is working well with the ferrets, dosent move a muscle when she sees or smells them, actually she loves them. Really, its just depends on the dog, you could have a dog best known for loving and caring for ferrets but there could be a few of that breed that would kill them.