Perfect Comparison of Nutritional Differences Between Dogs and Cats

DigestiveComparisonsMeongsiljang Veterinary Advisory Board

Dogs and cats have different digestive physiologies, so the types and proportions of nutrients they need vary significantly. Here’s a clear overview of key differences, such as protein, taurine, and arachidonic acid.

Why Do Dogs and Cats Have Different Nutritional Needs?

A comparison image showing dog food and cat food side by side.

Comparing the nutritional needs of dogs and cats starts with the fundamental differences in their metabolism and essential nutrient requirements. The key takeaway is that cats have a stricter carnivorous nature, while dogs are more omnivorous. Although both species belong to the order Carnivora, their metabolic and nutritional needs diverged during evolution. Feeding dogs food to cats can lead to deficiencies in nutrients essential only to cats, such as taurine, arachidonic acid, and vitamin A (retinol). Conversely, feeding cat food to dogs can result in excessive protein and fat intake, leading to nutrient overload and obesity. Therefore, providing species-specific food tailored to each animal’s needs is essential.

Two Animals with Different Digestive Physiologies

Dogs, despite being in the same order as carnivores, have a metabolism that is relatively closer to omnivores, allowing them to flexibly utilize various nutrients, including carbohydrates. In contrast, cats have low activity of enzymes involved in glucose metabolism (such as glucokinase) and are structured to prioritize protein as an energy source. According to veterinary nutrition textbooks, cats cannot reduce the activity of enzymes that break down amino acids (amino transferases and urea cycle enzymes) even when protein is deficient or they are fasting. As a result, even with insufficient protein intake, cats continue to use amino acids for energy, rapidly depleting their own muscle proteins and becoming prone to protein deficiency.

Comparison Table of Key Nutrient Requirements

Item	Adult dog (general adult)	Adult cat (general adult)
Minimum protein (dry matter basis)	18%	26%
Minimum fat	5.5%	9%
Taurine	Can be synthesized in the body	Essential — must come from the diet
Arachidonic acid	Synthesized from linoleic acid	Essential — must come from the diet
Vitamin A	Can be converted from beta-carotene	Requires direct intake of retinol
Niacin (B3)	Synthesized from tryptophan	Must be supplied directly through the diet

Compiled based on the AAFCO (Association of American Feed Control Officials) adult maintenance standards.

Four Nutrients Essential Only for Cats

When reading cat food labels, there are certain ingredients you should always check for.

Taurine: This amino acid is essential for maintaining heart muscle and retinal health. A deficiency can lead to dilated cardiomyopathy and blindness.

Arachidonic acid: This fatty acid is necessary for regulating inflammation and supporting skin and reproductive function. It is found only in animal fats.

Retinol (Vitamin A): Cats cannot convert beta-carotene from carrots into vitamin A.

Niacin: Unlike dogs, cats can hardly synthesize niacin from tryptophan.

An image visualizing essential nutrients for cats

Problems Arising from Feeding the Wrong Food

Feeding your dog cat food over a long period can lead to excessive protein and fat intake, resulting in nutritional overload and obesity. Conversely, if a cat is fed dog food for an extended time, the lack of taurine can cause taurine-deficient dilated cardiomyopathy or retinal degeneration (blindness). By the time symptoms become apparent, heart or retinal damage is often already advanced. While an occasional meal or two in an emergency is unlikely to cause harm, you should avoid switching your pets’ diets for several days or longer.

Differences in Carbohydrate Metabolism Are Also Decisive

Dogs can relatively efficiently use carbohydrates such as grains, potatoes, and sweet potatoes for energy. In contrast, cats have low activity of glucokinase, an enzyme essential for the first step of glucose metabolism, making them metabolically less suited to carbohydrate-heavy diets. According to veterinary nutrition textbooks, cats are naturally adapted to low-carbohydrate diets, so a diet higher in protein and fat aligns more closely with their natural dietary needs. Therefore, it is recommended that cat food be formulated primarily around protein, avoiding excessively high carbohydrate levels.

Water Intake Methods Differ as Well

Cats naturally drink less water and rely on moisture from their food, so feeding only dry kibble can easily lead to insufficient overall hydration. Veterinary nutrition textbooks link a cat’s water intake to lower urinary tract health, as inadequate drinking increases the risk of bladder and urinary tract issues. The key management strategy is to incorporate wet food or increase water consumption. Dogs, by contrast, tend to drink water more readily, so they face less pressure to maintain hydration. However, for both species, providing fresh water that is freely accessible around the clock is essential.

At-a-Glance Safety Ratings by Nutrient

Safe

타우린(Taurine)

심장·망막 건강 유지

Dosage: 고양이 1000mg/kg 사료 이상

미국사료관리협회 권장

Safe

아라키돈산(Arachidonic acid)

피부·염증 조절

Dosage: 고양이 사료 필수 포함

미국국립연구위원회 기준

High risk

양파·마늘 성분

없음 — 오히려 독성

Dosage: 0 (급여 금지)

적혈구 파괴 유발

Caution

우유(락토스)

권장하지 않음

Dosage: 성체는 제한

설사 유발 가능

Feeding Tips for Dogs and Cats Living in the Same Household

It’s common for dogs and cats to steal each other’s food when they live together. To prevent this, store cat food on high shelves or in a room with a pet door, effectively separating the spaces so your dog can’t access it. Feed them at different times and remove their bowls immediately after they finish eating. Following these simple guidelines can almost entirely prevent nutritional imbalances and obesity.

Reviewed by a veterinarian

Dr. Tony — Punnawat Phongkittirak

Veterinarian

A veterinarian who majored in veterinary medicine at Khon Kaen University, Thailand, and completed the IVSA program at North Carolina State University in the United States. Drawing on clinical experience at animal hospitals, he works in the pet healthcare field and is dedicated to building a digital care environment that connects pet parents with veterinarians.

Frequently Asked Questions

Can I give my dog a cat food can as a treat?

An occasional spoonful or two is fine, but it shouldn’t be a staple. Cat food contains significantly higher levels of protein and fat than dog food, so feeding it regularly can lead to nutritional excess and obesity.

How many days can I feed my cat dog food?

This is only for true emergencies lasting one to two days. Cats must obtain taurine, arachidonic acid, and retinol (vitamin A) exclusively from their diet, so feeding them dog food for more than a week can lead to deficiency symptoms.

Is it safe to feed vegetarian dog food to both dogs and cats?

We strongly advise against feeding cats a vegetarian diet. Poorly formulated plant-based meals can lead to blindness in cats, and because they require many nutrients found only in animal-based ingredients, deficiencies can develop easily. It’s also best to avoid switching dogs to a vegetarian diet without veterinary guidance.

Are the ingredients in dog and cat food from the same brand similar?

Even if the ingredients are similar, the ratios of protein, fat, and taurin can be completely different. You should not switch to a different brand just because it has the same name; you must always use the product specifically formulated for your pet.

Can I give adult-formula food to kittens and puppies?

Growing pets have much higher energy and protein requirements, so adult formulas won’t meet their needs. Be sure to choose products specifically labeled for kittens or puppies, or those marked “all life stages.”