I was surprised to learn how dog un-friendly Yosemite is. We were there in April, with our dog, for 4 nights. We also have small kids (2, 5, and 8) so big hikes were out of the question. We took our dog on small hikes around the Wawona Meadow and on the lower Yosemite Falls trail ... both are dog friendly. For other hikes we left our dog in the trailer, where he is very comfortable and doesn't bark.
It was April, so heat wasn't an issue. During the summer it could very well get to hot to leave a dog in the trailer. Also, if your dog is not very used to being left behind, and will bark at every thing that moves outside, you should not be leaving it behind.
