I would put a little extra security on the dog (I.e. a pinch collar or a choke collar) and have him on leash, while letting him into the room with the cat. I would also have some treats handy.
I would watch his reaction. If he goes after the cat, a big collar correction could be enough to deter him. If he ignores the cat, or scopes him out and then returns to you - I would give him a treat and praise him for returning to you.
Hounds are not usually good with cats. Growing up we raised coonhounds, and when we sold puppies it came with an explicit warning that cats and hounds don't usually mix. Some of them were fine all their lives with the kitties, others were not. Unfortunately the two breeds this dog is a mix of are not notorious for being easy to train either, so it will require you to be firm about the collar correction and praise when he does a right thing. It may just take time.
I would watch his reaction. If he goes after the cat, a big collar correction could be enough to deter him. If he ignores the cat, or scopes him out and then returns to you - I would give him a treat and praise him for returning to you.
Hounds are not usually good with cats. Growing up we raised coonhounds, and when we sold puppies it came with an explicit warning that cats and hounds don't usually mix. Some of them were fine all their lives with the kitties, others were not. Unfortunately the two breeds this dog is a mix of are not notorious for being easy to train either, so it will require you to be firm about the collar correction and praise when he does a right thing. It may just take time.