My chihuahua got an aspirin last night and today he is acting like he can hardly walk. He acts like his back legs are stiff and he drags them. Mostly he is just laying around. Do you think this is a side affect of the aspirin or something else? If it is the aspirin what is the best thing to do about it?

Why did he need the aspirin in the first place, did a vet prescribe it, you just gave it to him, or he swallowed it by accident? Aspirin could cause kidney failure with symptoms like you describe especially some aspirins that have caffeine added. Get him to vet ASAP

Assuming it was an aspirin for humans, its probably as if a 160 pound person took about 15 aspirin tablets. Could cause bleeding too. Many areas have emergency vets too.

Yes, take him to the vet asap! I know that cats aspirin is dangerously toxic to cats. It can kill them. I'm also concerned because of how small your dog is.

That's a big dose for a tiny dog! Was he already having a little trouble walking before?
Aside from the side effects of the aspirin that the folks above have described, it sounds like he may have slipped a disc in his back. He needs to see the vet immediately.