I had a Patterdale, she was a chainsaw on legs! She was about 22-24lbs and could kill a 35 lb coon. She was the most athletic dog I ever saw, in a hole she wouldn't quit. very human friendly but she developed a problem of being dog aggressive towards some females. I'm sad to say she got loose once when we were gone and killed my 45lb Airedale
That was the end of her. Speaking of rats Mudderchuck my boy had 2 pet rats in a cage, well on a cold night i let my Patterdale in the house. She made a line straight upstairs, i thought to play with the kids. Instantly I heard a loud bang and the kids yelling. She tore the top off the rat cage and killed one rat and was going for the other b4 the kids grabbed her, she hated those rats. If you get a Patterdale you got to be training and on them all the time, I trained her not to kill the pet cat but it was a challenge and i would never fully trust her around cats. The 2 breeders i know won't sell them to strangers, they trade them or give them to other hunters they know.