Ask Your Vet: How Much Should You Feed Your Pet? By Stefanie Wong, DVM

For this month’s article, we polled our technicians to see what some commonly asked questions they get from pet owners are. One of the questions they get asked a lot is: how much should I be feeding my pet?

It’s a great question. Here, I’ll explain the calculations we use to determine how much your pet should eat.

The first thing you should know how to calculate is the RER, which stands for Resting Energy Requirement. This represents the calories your pet requires to carry out daily body functions like breathing, digesting, and thinking.

1. Determine your pet’s weight—feel free to come into Bishop Ranch Veterinary Center and use our scale so you can start with their current weight. Another option is to pick them up and step onto your scale at home, then subtract your weight from that number. This is their weight in pounds.

2. Now, we need to translate that weight into kilograms (kg). You do this by dividing their weight in pounds by 2.2.

3. We will use a rough formula to get their RER, which is:

• RER = 30 x (body weight in kg) + 70
   

4. The number you get from this formula is the kilocalories (kcal) they need daily for daily body function.

• For example: Buddy weighs 20 lbs., or (20 divided by 2.2) = 9.1 kg

• His RER = (30 x 9.1) + 70 = 343, which is the number of kcal Buddy needs to eat daily.
   

5. Look at the bag label on your pet food. You’re looking for ___ kcal/cup. This will allow us to take the final step and calculate how much you should actually be feeding. For example, Blue Buffalo Life Protection formula with chicken and brown rice contains 378 kcal/cup.

Going back to Buddy, he can eat 343 kcal/day. If you divide 343/ 378 = 0.9 cups, he should get under 1 cup/day to meet his resting energy requirement. However, Blue Buffalo’s label recommends feeding him anywhere from 1 ¼ – 1 ¾ cups/day. Why the difference?

Growing, active, or working dogs require more energy and calories. For example, a growing puppy requires 3 x RER (going back to the example with Buddy, if he were an 8-week-old puppy, we would actually want to feed him 3 x 343 or 1029 kcal/day!). Active, working dogs (for example, sled, agility, and police dogs) require anywhere from 2-5 x RER. That being said, most average pet dogs only need 1.6 x RER.

Let’s say your dog is overweight. In that case, we’re aiming for weight loss. You would want to feed only 1 x RER (using the dog's ideal weight rather than its actual weight).

In contrast to dogs, cats have much lower energy requirements. Neutered or spayed cats should be fed only 1.2 x RER, and geriatric (>10 years old) cats only need 1 x RER. Like dogs, if your cat is overweight, we should target 1 x RER (using their ideal weight).

Most pet food feeding charts provide estimates that cover ranges for intact, active animals. However, their feeding recommendations often exceed the average pet's needs.

Also, remember that treats should be included in your pet’s total daily caloric intake.

The Bottom Line

All pets are individuals. Due to differences in breed, activity level, and inherent metabolism, these numbers can only estimate how much you should be feeding. The amount itself will need to be tailored to your pet and may need to change depending on how their weight fluctuates in response to the amount you’re feeding.

How to know you’re on the right track

I use a pet’s Body Condition Score (BCS) to guide my recommendation on whether a pet needs to gain or lose weight. Ideally, you should be able to easily feel (but not see) your pet’s ribs – there should be no fat cushioning in between the skin and the ribs. Your pet should have a waistline from the side profile and from above.

Refer to this website to see what your pet should ideally look and feel like.

In Summary

I recommend you use this article and our calculations as a starting point and then track progress using a diary with monthly weigh-ins. At your next annual visit, your veterinarian can help you determine your pet’s body condition score and ideal weight. It will take some work, but it’s worth it. Getting your pet to an ideal weight gives it the best chance for a healthy, happy, long life. 

Tags: ask the vet, feeding amounts