InfusionFox
Nutrition

Energy requirements (RER / MER)

Daily caloric target for adult dogs and cats: routine maintenance and weight-loss programs. Pick the species, the purpose, and an optional food caloric density to get a concrete kcal-per-day target and a feeding plan.

RER and target intake

Calculates resting energy requirement using the allometric formula (RER = 70 × BW0.75) and a target daily caloric intake based on purpose. Maintenance for routine feeding plans; weight loss for obesity management.

Body condition score on the Laflamme 9-point scale. 5/9 is ideal. For weight loss, the calculator estimates ideal weight from BCS automatically (each unit above 5 ≈ 10% over ideal).
Optional. If set, overrides the BCS-based estimate. Use this when you have the patient's documented previous lean weight.
Food (optional)

Fill these in to convert kcal target into cups or cans per day.

Read off the food bag or can label. Most pet food labels publish kcal/cup for dry and kcal/can for canned.
Splits the daily target into per-meal portions. Default 2.
Awaiting input

Enter a patient weight to see the result.

Reference

Formulas used

Resting Energy Requirement (RER)

Allometric formula, valid for all body weights:

$$\text{RER} = 70 \times \text{BW}^{0.75}\,\text{(kcal/day)}$$

A linear approximation (70 × BW + 30) exists for BW 2–25 kg but overestimates outside that range. InfusionFox uses the allometric form throughout.

Maintenance, dogs

MER = RER × activity factor. Adult dog factors per Ettinger Ch. 147 / NRC 2006:

  • Inactive / neutered indoor: ×1.4, Sedentary, neutered, indoor pet dog. NRC 2006 inactive equation: 95 × BW^0.75 ≈ 1.36 × RER. InfusionFox uses 1.4 as a rounded value.
  • Typical adult pet dog: ×1.5, Standard adult pet dog with normal daily activity. Within the Ettinger Ch. 147 stated range of 'RER × 1.4–1.6 used to determine adult MERs.' Specific 1.5 multiplier is clinical convention.
  • Active / outdoor / kenneled: ×1.85, Active dogs with regular exercise. NRC 2006 active/kenneled equation: 130 × BW^0.75 ≈ 1.85 × RER.
  • Working / racing / hunting: ×2.5, Working dogs with sustained heavy exercise. Multiplier is highly variable per Ettinger Ch. 147; 2.5 is a starting estimate, adjust based on body condition. Not a published NRC value.

Maintenance, cats

Cats use NRC 2006 equations directly, keyed to body condition score rather than activity level. NRC notes (p. 93) that activity factors have less obvious effects on cats than on dogs.

$$\text{Lean cat (BCS} \le 5\text{): MER} = 100 \times \text{BW}^{0.67}\,\text{kcal/day}$$ $$\text{Overweight cat (BCS} > 5\text{): MER} = 130 \times \text{BW}^{0.4}\,\text{kcal/day}$$

The lower exponent for overweight cats reflects that adipose tissue is less metabolically active than lean tissue, per-kg requirements drop with increasing body fat.

Weight loss

Calculated against ideal body weight, not current weight:

$$\text{Dog target} = 63 \times \text{IBW}^{0.75} \quad (\text{minimum } 42.6 \times \text{IBW}^{0.75})$$ $$\text{Cat target} = 52 \times \text{IBW}^{0.711} \quad (\text{minimum } 42.2 \times \text{IBW}^{0.711})$$

Reassess every 2–4 weeks. Adjust by 10–20% based on actual loss vs target rate (1–2%/week dogs, 0.5–1%/week cats).

Worked example with current inputs

Enter a patient weight to see the worked example.

Sources

  • Ettinger SJ, Feldman EC, Côté E, eds. Textbook of Veterinary Internal Medicine. 9th ed. St. Louis, MO: Elsevier; 2024. Chapter 147 (Nutrition for Healthy Adult Dogs, Box 147.1) for dog maintenance. Chapter 150 (Obesity) for the IBW-based weight-loss formulas (dog and cat).
  • National Research Council, Committee on Animal Nutrition. Nutrient Requirements of Dogs and Cats. Washington, DC: National Academies Press; 2006. Energy chapter (Ch. 3), p. 95, adult cat MER equations (lean and overweight).
  • Laflamme DP. Development and validation of a body condition score system for cats. Feline Pract 1997;25(5-6):13–18. Source of the 9-point BCS scale used to estimate ideal body weight from current weight and BCS.