You first need to determine your horse's current body weight. The following steps will provide you with a more accurate assessment of his actual weight than a standard commercial weight tape.
1. Using a flexible (but not stretchy) tailor's measuring tape, measure the circumference of your horse's girth, in inches, running the tape just behind the elbow on both sides and straight over his withers (see photo at right). Record this number.
2. Using a rigid carpenter's measuring tape or a 6-foot ruler, measure the length of your horse's torso on one side, in inches, from the point of his shoulder to the point of his hip. Record this number.
3. Apply your measurements to the following formula:
[(girth)2 X length] / 330 = body weight
Example: Horse with a 66-inch girth and a body length of 62 inches. His body weight would be:
662 X 62 / 330 = 818.4 pounds
Once you have a good estimation of your horse's body weight, you need to determine his "body condition" by rating six key conformation points via visual appraisal and palpation (feel), according to the amount of flesh or fat on his:
C. Crease of back
F. Behind the shoulder, at the girth
For each of the following checkpoints, select the description that most accurately describes your horse's body. Then, add up the total number of points you've recorded and divide that total by three to calculate his body condition on a score of one to 10 (see interpretations of score below).
a. You have to dig to find them - 5 points
b. They're not visible, but you can easily feel them - 3 points
c. You can see themn - 1 point
a. A thick "loaf" of fat behind his shoulders blends them flush with your horse's ribcage - 5 points
b. His shoulders are rounded and blend smoothly into his body - 3 points
c. Bone structure of shoulders is easily visible with no fatty covering - 1 point
a. There's a prominent crease along his back - 5 points
b. His back is level, with no crease or ridge - 3 points
c. There's a ridge along his back - 1 point
a. His tailhead is surrounded by bulging fat - 5 points
b. Fat can be felt around his tailhead, but isn't visible as a bulge - 3 points
c. The tailhead bone is prominent - 1 point
a. There's a sofa-like cushion of fat on both sides of his withers - 5 points
b. His withers are slightly rounded, but not buried in fat - 3 points
c. The bone structure of his withers is prominent - 1 point
a. There's a doughy loaf of fat along the crest of his neck - 5 points
b. His neck is smooth - 3 points
c. The bone structure of his neck is visible - 1 point
NEXT: Total the number of points and divide by 3. This number is your horse's estimated body condition.
Interpreting your horse's score:
1 = Poor condition
2 = Very thin
3 = Thin
4 = Lean
5 = Neither fat nor thin
6 = Show shape
7 = Plump
8 = Fat
9 = Very fat
10 = Dangerously obese
If your horse scores 1 to 3, he needs to gain weight; if he scores 8 to 10, he needs to shed some serious pounds. In either case, consult your vet for a safe weight-loss (or gain) program to achieve your horse's optimum condition. Keep in mind: Even though you may enjoy the satisfaction of giving your horse lush grass or sugary treats and grain, you're going to increase his life span--and make his life more enjoyable--by keeping him fit.
For more information on how to help your horse lose weight, refer to the article "Fit (Not Fat) is the Best Color" (How to Manage Your Horse's Weight) in the November 2007 issue of Horse & Rider magazine.