Masking pain or illness is an evolutionary survival mechanism in dogs, which makes it hard to tell at times whether Fido is unwell. Here are some signs of trouble to look out for (when in doubt, always consult your vet):
Activity level changes: Lethargy, restlessness, or a less cheerful dog can mean something is wrong.
Mood swings: Happy one day, grouchy the next? Pain could be at the root. The same goes for a pup who’s happy in the morning, but cranky at night.
Sudden aggression: If an otherwise friendly dog, especially an adult, shows aggression, be sure to include pain as one of the chief suspects.
Loss of appetite: Could be pain, illness, or something less alarming, but a lack of appetite always warrants a trip to the vet.