My dog started vomiting its food yesterday, is unsteady, trembling, shaking its head, had soft and loose stools, and has not eaten all day. No blood. What is wrong?

Vomiting, unsteadiness, body trembling, head shaking, soft stools, and not eating may be enteritis from a foreign-body blockage or diseases such as canine distemper or parvovirus. A veterinary examination is recommended to find the cause and treat it specifically.

These conditions are serious, so timely treatment matters; delay greatly increases the difficulty of treatment.