Do dogs get this as a symptom of concussion? Earlier today we noticed that Charlies pupils were vastly different sizes. The right was very dilated, and the left like a pinpoint. It's back to normal now. I put a blanket over his crate and they were both huge, then shined a light in his eyes and they both got small. What could it be? The websites we looked it up on all said it could be from neurological problems, or cancer, or pressure inside the eye, etc. but none mentioned head injury. Now, the way Charlie plays is very rough. Basically he rams into things at top speed. Once he broke our gate by ramming into it. I'm wondering if he might have rammed a fencepost, or the corner of the garage, or a tree, or the ground, etc. and gave himself a concussion. Especially since it's gone for now. If it comes back, we will definitely take him to a vet. I might just take him in to be cerf'd anyway, since it's only $25 or so. Do they test eye pressure at all in the cerf test?