Canadian Veterinary Medical Association

Good quality photographs are essential. They should be 35 mm or digital photographs in colour, with sufficient lighting, and close enough to identify the animal and the lesions.
A ruler should be included in the photograph to show the size of the wounds.
Photographs should be taken throughout the recovery period to show the stages of healing.
All photographs should include a label marker with the name of the owner or number of the case, the date, and any other pertinent information. Additional information including the photographer's initials, place where the photographs were taken, etc., can be included in the record and on the back of the photos.
Save digital photography cards and mark as evidence.
Videotapes can be helpful if there are musculoskeletal injuries or neurological deficits that can best be appreciated via a moving image. Comments during the video should be professional and confined to remarks about the animal's medical condition. Background conversation should be avoided.
Remember that a significant amount of time may pass before a case comes to trial; photographs will be the only way to show the severity of the initial injuries.