Your vet can assess vital signs, body temperature, heart rate/rhythm, and will ask you questions about your pet's habits or recent behaviors that will hopefully aid in finding out why your pet is not acting as s/he normally does. Your veterinarian may suggest some lab work (blood, urine, stool) to further investigate what may be going on. It may be something simple, it may be an early indicator of something serious.
Early detection and prevention is always the best - both for your pet's health and ultimately for the cost of treatment. The "wait and see" approach is OK for perhaps a day if your pet is not in pain, still eating, able to relieve themselves normally, etc., but even so, more than 24 hours of being lethargic or "depressed" warrants at least a phone call to your veterinarian to discuss your concerns.
If your pet is in pain, won't eat, can't urinate, experiencing bouts of vomiting and/or diarrhea, please call your vet as soon as possible. These situations can be (or become) quite serious in a short period of time.
Photo credit: Boris the Dog © Jackie Gagarin Curry "octoberdog" on Flickr


