I find it unacceptable that I have never seen this pic posted on a chan board before.SPOILER: The mouse was indeed owned by the cat.
shoop
I say no: http://flickr.com/photos/cloud_nine/15354825/See also the next pic: http://flickr.com/photos/cloud_nine/22462003/in/photostream/Those animal photographers at Flickr are not known to shoop their pics.
Grasshopper mouse, demonic little things.