My dog ate cat food. What to do for stomach upset and bloat?

Oh no, that was naughty of Lady to eat the cat food. Certainly eating too much food can lead to bloat, but one to two cups isn't a lot of food to a large dog such as a Golden Retriever. You could see some stomach upset from it such as the diarrhea you have described, but she won't die from it. I can give you a home remedy to try to see if that helps her stomach. Withhold food for 12-24 hours, then feed a bland diet of boiled white meat chicken (no bones) and white rice in small amounts several times a day for a couple of days. Then slowly add back in her normal diet.

I will also give you that symptoms of bloat just in case, but as I said, it's very unlikely that this amount of cat food will cause bloat. Signs of bloat include attempting to vomit but being unable to, enlarged abdomen, pacing, restlessness, looking at her stomach, labored breathing, and excessive drooling. If you see any of those signs, rush Lady into a vet immediately. Otherwise, she should be ok :-)