My dogs love to chase squirrels. Actually, when they see a squirrel, they focus in on the squirrel to the exclusion of anything else. I bet that if I let them tree a squirrel and left them there, they'd pass out from exhaustion before they'd give up trying to get the squirrel.
This is actually very annoying - dragging two 80 lb dogs in the opposite direction of a squirrel they want to chase. If only my dogs could read and understand the following news item, they might give up on chasing squirrel's entirely: BBC NEWS | Europe | Russian squirrel pack 'kills dog'
If you think that this is just something that happens in Europe (they're kinda weird over there, aren't they?), think again: When Squirrels ATTACK.
3 months ago