My dog just nibbled a single plain potato chip, do I need to call the vet?

It is not an emergency, but you should still keep an eye on your dog. A plain potato chip contains a lot of salt and fat, and many commercial varieties also have onion or garlic powder, which can be irritating in larger amounts. One small bite is unlikely to cause serious harm, though it may lead to mild stomach upset. Monitor your dog for vomiting, diarrhea, or excessive thirst over the next few hours. If any of those symptoms develop, give your regular veterinarian a call.