Why are anual exams for my pet important?

As the saying goes, an ounce of prevention is worth a pound of cure. 

Veterinarians recommend regular wellness exams for the same reason your physician and dentist recommend them – if you can detect a problem in its early stages, it's more likely to be treated and resolved with less expense, less difficulty and better success.

Vaccinations, heartworm prevention and routine deworming are important components of wellness care and can prevent diseases that are not only life-threatening, but very expensive to treat.

But what about the physical exam? Is your Vet really doing anymore than petting your animal?

Fact is, the physical exam is arguable the most important part of your pet's office visit. Through the experience of knowing what to look for, your veterinarian can determine a great many things from the physical exam.

Take a look at what a Vet is actually looking for when they give your pet it's physical exam. 
 
1. Start at the head.
When looking at the nose for crusties, color loss, change in texture, etc. and checking the teeth, lips, gums your Vet is looking for infection, hair loss, growths, color change, ulcers, etc. They might attempt to look at the back of the mouth for growths, ulcers, etc. sometimes squeezing the head muscles looking for discomfort that may indicate a headache or jaw pain. Your Vet will feel all the lymph nodes, under the jaw, in front of the shoulders, armpits, inguinal and behind the knees.

2. The eyes, eye lashes, lids.
They look at the pupils for size/symmetry. They may push back on the closed eyeball, looking for any pain.

Sometime they bring out the opthalmoscope to look at the back of the eye mostly looking for cataracts, and retinal hemorrhages. Did you know that there is a small window during which you have to get a cataract fixed?

3. The ears.
They visually inspect the pinna (floppy part) for hair loss, scabs, crusts, scratches, scrapes, etc. looking into into the ears with an otoscope to check for infection, polyps and such.

4. Musculoskeletal System
Are their reflexes okay? Can they feel their feet? Can they feel pain? For neck pain, your Vet may move the head all the way up, down, left and right. For back pain they may squeeze all along the spinal cord from side to side and push down from the top.

5. Rubbing the belly!
Your Vet will palpate the abdomen for organ enlargement (spleen, liver, masses). They check to see if they slip around like they should or are they all stuck together from dehydration (a "doughy" abdomen). Does the patient have a super full bladder indicating an obstruction? Does it hurt? In cats, they can even  feel the kidneys. 

All this time your Vet is checking the
Overall physical condition of the patient.
Too skinny? Too fat? Just right? Any muscle wasting? Pain? Is he/she alert? Disoriented? Depressed?

How’s his/her coat and skin?
Bald? (If so: symmetrical or patchy? Smooth or scaly?) Stinky? Rough? Discolored? Thin? Lumps or bumps? Scrapes or scratches?

Whether a cat or dog owner, your expert Veterinarian can identify things that you will miss. Things you think are normal. Annual exams give you and your pet's doctor the chance to review your pets overall health and ensure they are with you for years to come.


source: http://www.petmd.com/blogs/thedailyvet/vcarroll/2011/apr/the_anatomy_of_a_physical_exam-10992