This old findavet article from YT's Emergency Library might help also:
http://www.yorkietalk.com/forums/eme...-dog-pain.html Here is part of that article below. Note the bolded section:
What are the Symptoms that My Dog is in Pain?
“The first rule is to assume pain is present if it seems logical after an injury, surgery or medical condition that would be painful for us,” Aldridge said. “
You watch for the subtle signs: your pet is hiding or lethargic, less active, eating less … your dog shows unusual reactions when handled, such as whining or acting aggressive. Any change in behavior can signal pain and should be checked out by your veterinarian.”
The ASPCA concurs: “Irregular behavior patterns are often the first sign that your pet is ill or in pain.”
Along with the pain symptoms Aldridge mentioned, these are some of the other signals to look for, according to the American Animal Hospital Association (AAHA):
Enlarged pupils
Flattened ears
Hair standing up in places
Restlessness
Excessive panting when resting
Repetitively getting up and lying down again
Continually licking or scratching one particular area
*Clinginess/neediness
*Shaking or trembling
Call your vet if your dog is showing any of these signs. If your dog has a disease or medical condition, the ASPCA offers this advice: “If you’re unsure of how much your pet is suffering, keep a daily record of good days and bad days. It’s also important to ask your veterinarian for the exact signs of suffering likely to be associated with your pet’s condition or disease.”