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The Daily Vet by petMD

The Daily Vet is a blog featuring veterinarians from all walks of life. Every week they will tackle entertaining, interesting, and sometimes difficult topics in the world of animal medicine – all in the hopes that their unique insights and personal experiences will help you to understand your pets.


For years, preoccupation with achieving a certain weight has been the goal of weight loss programs. But weight has proven to be an inaccurate measure of fitness.

In humans, the Body Mass Index, or BMI, has replaced weight. The BMI compares weight to height. Tall people have more bone and muscle, which weighs more than fat, so they could be "overweight" but not fat. A short person weighing the human average of 150 pounds could be carrying excessive amounts of fat and still be "normal weight." BMI corrects for these differences.

"Ideal weight" in pets has similar problems. Breeding practices have led to complicated breed weights. Blood lines within breeds often have very different body types, with differences as great as 20 pounds, and gender differences can have the same or greater weight variations. Cross breeding of different body types, like Labradoodles and Puggles, really stretch any notion of an ideal weight. "Mutts" resulting from multi-breed mixes allow only a guess for ideal weight because the major breed may be unknown.

Why is this important?

Because feeding recommendations are based on weight. Every overestimate of ideal weight by one pound will result in overfeeding by 53 calories! So an "ideal weight" difference of 2-5 pounds in a small breed could mean overfeeding by 100-250 calories. For larger breeds the difference could mean overfeeding by 500-1000 calories. Little wonder that half of the pet population is overweight. This is probably a major cause of failure in weight loss programs, since choosing a generous "ideal weight" can overestimate the calories fed during the diet.

What is the alternative?

In pets, the Body Condition Score (BCS) has proven to be a superior method for assessing fitness. It is a visual system, so scales are unnecessary, and experiments have confirmed that this simple method compares with techniques that are considered to be the gold standard for measuring body fat. Veterinarians use two BCS systems: a 5-point and a 9-point.

How does BCS work?

A BCS requires looking at a pet from the side, and from above looking toward the head. From the side, the perfect pet has a tight "tummy tuck" toward the hips; the ribs are not distinctly visible but are easily felt. From above, the same pet should have a gentle hourglass shape from the chest to the hips. This perfect pet is given a score of 3 in the 5-point system, and a 4-5 in the 9-point system.

A slightly sagging belly with ribs that are covered by a slight excess of fat and a straighter profile from the top is a 3.5 in the 5-point; 6 in the 9-point.

Greater difficulty feeling the ribs, loss of tummy tuck, and a straight to slightly bulging profile from above rates a 4 in the 5-point; 7 in the 9-point.

Inability to feel the ribs, abdominal sag, and a bulging profile from above with fat deposits on the hips and at the base of the tail scores a 4.5 in the 5-point; 8 in the 9-point.

Massive fat deposit on the chest, shoulders and neck, distended abdomen, and an extreme bulging profile from above with excessive fat deposits on the hips and tail base ranks a 5 in the 5-point; 9 in the 9-point.

Conversely, pets with a BCS of 1-2 in the 5-point system or 1-3 in the 9-point system are considered too thin.

Pets should be fed enough to maintain a BCS of 3 in the 5-point system, and 4 in the 9-point system. Dieters should have the same target BSC scores. A pet’s weight at a score of 3 or 4 is its individual healthy and ideal weight.

What is your pet’s BCS?

Dr. Ken Tudor

Images: HelleM / via Shutterstock; Body Condition Score Chart via Pet Food Direct

For downloadable BCS charts for dogs, cats, and rabbits, visit PFMA UK

Comments  6

Leave Comment
  • Four of Five
    02/09/2012 08:06am

    Four of five are in great shape. We're working to slim down number five.

  • JW sports big belly
    02/09/2012 10:16am

    Thank you for this enlightening update Dr. Tudor! As a former fitness trainer I'm very familiar with BMI and used to tell my clients--DON"T GO BY WEIGHT. use your waistline as indicator.

    But all indications say I have some work to do with my furry children. Two have low blood sugar and have to nibble throughout the day which means JW eats larger quantities of their food and naps for longer than normal sessions hence the hanging belly. I don't want to separate them and lock up in smaller rooms hence one gets very vocal and I don't want to disturb my condo neighbors. Still trying to figure out solution. May have to invest in cat sitter for controlled feedings. Which is actually great idea just need to rearrange finances. Their my children so I have to make it a priority!

  • 02/09/2012 10:52am

    My favorite trick when dealing with different feeding requirements is the use of kitty doors. Most pet retailers sell doors that require a special tag on the collar to use, and there is an online manufacturer that makes one that only allows certain microchips through.

    The best is to install on an interior door and designate that room as the "food room"- the food is always out there for the skinny cats or those who need to nibble constantly through the day, and they are the only ones allowed access. Even some of my clients who rent have been able to talk to their landlords and get permission to set this up; they buy their own door and install the cat door and hang it, and keep the old door so it can be put back in place when they move.

    If the landlord won't go for that or there isn't a room in the home that would be appropriate to limit kitty access to, the other option is to build a large box for the same purpose and instal the door on the box. A large dog house with the "real" entrance blocked might be a good option, or building one from wood. This could lead to stalking behavior at the entrance, kind of like with some covered litter boxes, but would be worth a shot for a place with an inflexible landlord or a studio apartment with no real interior doors.

  • MiamiAngel
    02/09/2012 11:12am

    There is no doubt that cats are tough when it comes to weight loss, especially those with other confounding problems like JW. We will be discussing options in future blogs, but to be honest I keep my expectations low with cats. Their eating style of periodic grazing makes weight loss difficult in multi-cat households. Have you tried the food balls or food puzzles placed in hard to get places or atop cat trees to encourage exercise? The recommendation is 2-3 more balls than the number of cats with each containing no more than 30 calories.

    Dr. Tudor

  • BCS
    02/09/2012 06:20pm

    Both of my animals are thankfully well and healthy. I would place their BCS scores at 3 on the 5-point scale.

    At the veterinary clinic I work for, the doctor that I shadow for veterinary school combines weight and the BCS for her fitness evaluations. I like this method, because if the dog/cat/whatever looks good on the BCS scale and it's weight hasn't fluctuated significantly since the last time we saw it, we take that to mean that animal is at a good level of fitness.

  • tlyncourtney
    02/09/2012 09:29pm

    We are all in agreement. An animal's weight at its perfect BCS is the ideal weight that we want to maintain. But weight when the BCS is not a perfect 3 or 4 is more misleading. As you know fat is less dense and lighter than than bone and the water weight of muscle and organs. Because an animals weight consists of all three types of tissue weight doesn't distinguish body fat. The BCS has a high correlation to dual energy x-ray absorptiometry (DEXA) which is considered the gold standard for determining the percentage of body fat or fitness. Knowing the percent body fat helps design more effective weight loss programs than using "ideal weight" because of the problems I mentioned in the article.
    Thanks for the response and good luck in veterinary school. I hope you continue an interest pet weight loss and fitness.
    Dr. Tudor

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