This photo of Munch by Jill Goodell generated some discussion on the Yosemite Blog.
A commenter named Tom suggested he’d be within his rights to shoot a loose dog in Yosemite National Park. It’s illegal to be off-leash.
Seems to me Tom’s not actually threatening to shoot Jill’s dog, but rather was using exaggeration to make a point. Off leash dogs can wreak havoc with wildlife.
Click through to that post if you’ve an opinion to add: Yosemite Blog – The Last Straw
besthike.com 
I agree with you Rick: I think he was being tongue-in-cheek about how guns are now allowed in National Parks and how dogs off leash are not. Subtle humor that isn’t easy to spot, but an attempt at humor nonetheless.
I don’t own a dog and find it a bit annoying to pass leash-less dogs on the trail, but can you provide a few reasons how these dogs can “wreak havoc with wildlife?”
I was biking off leash trails with a dog the past few weeks.
She’d take off after any rabbit. But it seemed to me the rabbits enjoyed leaving her in the dust.
Once a coyote tried to lure my dog into the woods in order to make “dog food” of her. That didn’t work. She’s a little too big to kill.
Perhaps the worst case scenario would be a dog pestering a bear or cougar.