
Many conditions can induce pain: Not only injury and trauma, but other less obvious conditions including osteoarthritis or medical conditions as well.
Below are a few examples of causes of canine pain:
Information sources
The American Animal Hospital Association/American Association of Feline Practitioners Pain Management Guidelines for Dogs & Cats, 2007
Handbook of veterinary pain management. James S. Gaynor, William W. Muir III. Mosby Elsevier, 2nd edition, 2009
Pain management in small animals. A manual for veterinary nurses and technicians. Debbie Grant. Butterworth Heinemann, 2006