chihuahua showed up at our door last nite, no clue who his owner is. called the number on his tag & they said he wasn't their dog. too late to take him anywhere, so kept him overnight for his safety. so far, he won't eat anything but cheese. we have another dog, so i softened his food & chihuahua won't eat it. he doesn't want water either, but i gave him on fingers anyway so he wouldn't dehydrate. vet isn't open yet to call them but will take him there later this morning. he seems healthy & well-cared for, except for his way overlong nails. he had a good night & slept well with my son. he needs to have something to eat but really doesn't seem interested. we tried the 2 kinds of puppy food we have. we have tuna...would that be ok?