Calculation should include using the following formulas:

Resting energy requirement (RER) is a function of metabolic body size. Energy expenditure is related to surface area, and body surface area decreases as body weight increases. The equation for RER is the same for both cats and dogs. It is used to estimate the daily energy needed to sustain essential bodily functions (e.g. respiration, circulation, digestion, metabolism) while the dog/cat is at rest in a thermos-neutral environment.

RER (kcal/day) = 70 * (BWkg)^0.75

For any animal not completely at rest, supplementary energy is needed to sustain additional work (e.g. activity, life-stage or physiologic condition, dealing with environmental conditions). These total daily energy requirements can then be ESTIMATED by multiplying the RER by an appropriate factor to estimate maintenance energy requirement (MER).

Determine MER = Life‑Stage/Activity Factor × RER

Activity/Life‑Stage Factors:

Critical care: ×1
Gestation: ×1.6–2.0
Lactation: ×2.6
Growth (puppies): ×2–3

For dogs between 2 and 45 kg only:

RER ≈ (30 × BWkg) + 70 kcal/day
Then proceed to calculate MER = factor × RER.

For dogs <2 kg or >45 kg, always use the exponential RER formula:

RER = 70 × (BWkg)^0.75 kcal/day
Then proceed to calculate MER = factor × RER.

Calculating calories based on pet needs includes

RER = 70 × (BWkg)^0.75
MER = RER × activity/life-stage factor.

Teacher Resources:

Balancing bowl and brain: Tips for maintaining a healthy weight for your pet, Veterinary Teaching Hospital, Virginia-Maryland College of Veterinary Medicine, Virginia Tech
Calculating Calories Based on Pet Needs, Pet Nutrition Alliance
Nutrition Math 101: Important Calculations, Today’s Veterinary Nurse
Resource Center: Veterinary practice team resources from the 2021 AAHA Nutrition and Weight Management Guidelines for Dogs and Cats, American Animal Hospital Association (AAHA)

Process/Skill Questions:

What factors must be considered in determining the nutritional requirements for basic metabolic function?
Why is calculating MER for an animal important?
What is the difference between the RER and the MER?
How might overfeeding lead to a problem for the animal?
How do the nutritional requirements of an animal vary in relation to its age and life functions (e.g., growth, development, and reproduction)?