A juvenile cougar looks like a bobcat but with the longer tail.

First time I saw one I didn't know WTF I was looking at.

My cousin used to keep a pair of bobcats in a pen on his property down in CA. They were mean-looking. He also had a pair of rottweilers that were intimidating but nothing like those. They wouldn't go near the pen. Anytime the dogs got close, the tom would roll on his back like he was saying "Come get some!"
I asked what he did with 'em he said he got tired of feeding them so he just unlatched the cage and left for the day. After about a week the female split and never came back, after about 3 months the male quit hanging around the pen when he caught the scent of some poon.

I'd hate to see what'd be left of a dog after it was shredded up by one of those.