Evaluating your dog's weight

How skinny is "pretty skinny"?  How heavy is "not as thin as he should be"?  The Purina body condition system provides a uniform way to describe a pet's weight, from "emaciated" to "grossly obese"

1. EMACIATED
   Ribs, lumbar vertebrae, pelvic bones and all bony prominence evident form a distance.   No discernible body fat.  Obvious loss of muscle mass.
2. VERY THIN
   Ribs, lumbar vertebrae and pelvic bones easily visible.  No palpable fat.  Some evidence of other bony prominence.  Minimal loss of muscle mass
3. THIN
   Ribs easily palpated and may be visible with no palpable fat.  Tops of lumbar vertebrae visible.  Pelvic bones becoming prominent.  Obvious waist and abdominal tuck
4. UNDERWEIGHT
   Ribs easily palpable, with minimal fat covering.  Waist easily noted, viewed form above.  Abdominal tuck evident.
5. IDEAL
   Ribs palpable without excess fat covering.  Waist observed behind ribs when viewed from above.  Abdomen tucked when viewed from the side.
6. OVERWEIGHT 
   Ribs palpable with slight excess fat covering.  Waist is discernible viewed from above but is not prominent.  Abdominal tuck apparent.
7. HEAVY
   Ribs palpable with difficulty, heavy fat cover.  Noticeable fat deposits over lumbar area and base of tail. Waist absent or barely visible.  Abdominal tuck may be absent.
8. OBESE 
   Ribs not palpable under heavy fat cover, or palpable only with significant pressure.   Heavy fat deposits over lumbar area and base of tail.  Waist absent.  No abdominal tuck.  Obvious abdominal distention may be present. 
9. GROSSLY OBESE 
   

 chart and information courtesy of Ralston Purina