Sources & references

Every constant and formula used on this site comes from one of the references below. Each tool page also lists the specific sources behind that tool, directly under its formula.

Nutrition and energy requirements

• WSAVA Global Nutrition Committee. Nutritional Assessment Guidelines for Dogs and Cats.
• National Research Council. Nutrient Requirements of Dogs and Cats. National Academies Press, 2006.
• American Animal Hospital Association. Nutritional Assessment Guidelines.
• Association of American Feed Control Officials (AAFCO). Dog and Cat Food Nutrient Profiles.

Toxicology

• Merck Veterinary Manual. Chocolate Toxicosis in Animals (methylxanthine poisoning).
• ASPCA Animal Poison Control Center. Published methylxanthine dose thresholds.
• Pet Poison Helpline. Chocolate toxicity reference material.
• USDA FoodData Central. Theobromine and caffeine content of cocoa products.

Ageing and life stages

• American Animal Hospital Association. Canine Life Stage Guidelines.
• American Kennel Club. Dog age by size reference charts.
• Wang T. et al. Quantitative Translation of Dog-to-Human Aging by Conserved Rate of Epigenetic Drift. Cell Systems, 2020.

Preventive care and schedules

• WSAVA Vaccination Guidelines Group. Guidelines for the Vaccination of Dogs and Cats.
• American Animal Hospital Association. Canine Vaccination Guidelines.
• Companion Animal Parasite Council (CAPC). General guidelines for parasite control.

A note on ranges

Where two reputable sources disagree, we show the range rather than picking a favourite. Where a source gives a range itself, such as the energy multiplier for working dogs, that range is carried through to the result instead of being averaged into a single misleading figure.

Spotted an error or a better source? Tell us. Corrections to the underlying maths are the most useful thing you can send.