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calculate the perfect portion for your pet

Calculate the perfect portion for your pet

Are your pets eating too much or too little? Use this step-by-step guide to determine caloric requirements for them.

How do you know if your pets are eating too much or too little?
There are two steps to know if your pet is eating too much or too little. The first one is to determine the resting energy requirement (RER) and the second is to calculate the Daily Energy Requirement (DER) .

How to calculate the pet’s resting energy requirement (RER)?
RER represents the energy requirement of the pet while at rest at a controlled temperature. Here’s a simple formula determining RER for medium-sized pet (example: pets weighing between 2 and 45 kg):

RER for medium-sized pets= 30 x (body weight in kilograms) + 70

So if your pet weighs 20 kg, the equation would look like:
RER= 30 x 20 kg + 70 = 670
Your pet’s RER is thus 670 kcal per day.

Though this formula is in general adequate for medium-sized pets, it may not be accurate for small (less than 2 kg) or large pets(more than 45 kg). For these sizes, use:

RER for small/large pets= 70 x body weight in kilograms * 3/4.

So if your dog weighs 1.36 kg and we use the formula for small/large-sized pets
RER= 70 x (1.36 kg)3⁄4 = 88 kcal/day

How to calculate the Daily Energy Requirement (DER)?
DER is calculated by multiplying the pet’s RER by a coefficient based on life stage and body condition. Frequent coefficients are listed below:

Up to 4 months = 3 x RERGrowing kittens = 2.5 x RER
Over 4 months = 2 x RER
Normal neutered adult = 1.6 x RERNormal neutered adult = 1.2 x RER
Intact adult = 1.8 x RERIntact adult = 1.4 x RER
Obese prone = 1.4 x RERObese prone = 1.0 x RER
Weight loss = 1.0 x RERWeight loss = 0.8 x RER
Light work = 2 x RER
Heavy work = 4-8 x RER

Using the chart above, if your pet from the previous example is a growing kitten, we would calculate its DER as follows:
DER=2.5 * RER = 2.5 x 88 kcal/day = 220 kcal/day.

Another example, if your medium sized dog from the previous example is prone to obesity, we would calculate its DER as follows:
DER= 1.4*RER=1.4*670=930 kcal/day

It’s important to remember that all caloric calculations are estimates of the pet’s energy needs, actual caloric requirements may differ. However, these calculations provide an excellent starting point for every nutritional recommendation.

Feeding instructions
To determine the amount of food the pet should receive, simply divide the patient’s DER by the number of calories in a cup or can of the selected food or treat.
If your pet’s DER is 220 kcal/day, and dry kitten food “X” contains 523 kcal/cup:
220 kcal / 523 kcal per cup = 0.4 cups of food per day

This amount may be divided by the number of feedings the pet will receive. To know more about feeding your cat or dog, check out our previous blogs.

Christelle Bedrossian
Beirut, Lebanon


Author Info

Dietitian Christelle Bedrossian

Dietitian Christelle Bedrossian dedicates some of her time to address us through the various media outlets and provide answers to our questions. As a prominent professional in the field of dietetics, Dietitian Christelle Bedrossian is frequently hosted on several local and international television and radio stations to offer up to date advice and tips on health and nutrition. Dietitian Christelle Bedrossian is a writer and nutrition consultant for a variety of written publications, both print and online magazines and newspapers.