Dog and Cat Diets: What's the Difference?
Dogs and cats may share our homes—and sometimes even try to share each other's food bowls—but their nutritional needs are not the same.
One of the biggest differences comes from how their bodies have evolved to use nutrients. Dogs are generally considered omnivorous animals with carnivorous characteristics, while cats are obligate carnivores. This difference affects everything from their protein requirements and essential amino acids to the way they experience taste. Understanding these differences can help pet parents choose the right food and avoid accidentally feeding an unbalanced diet.
Are Dogs Carnivores or Omnivores?
Dogs are generally classified as omnivores, although they have many characteristics inherited from their carnivorous ancestors. Their digestive systems can utilize nutrients from both animal and plant ingredients. Dogs can eat meat while also digesting properly prepared carbohydrates and obtaining nutrients from ingredients such as grains and vegetables.
This flexibility means a nutritionally balanced dog food can contain a combination of animal proteins, fats, carbohydrates, fiber, vitamins, and minerals. However, being able to digest plant-based ingredients doesn't mean dogs don't benefit from animal protein. Protein supplies amino acids needed for maintaining muscles, tissues, enzymes, hormones, and many other important functions throughout the body.
Are Cats Carnivores?
Cats are obligate carnivores, meaning their bodies have evolved to depend on nutrients naturally found in animal tissues. They have specific nutritional requirements that make animal-derived nutrients particularly important. For example, cats have a dietary requirement for taurine and need adequate amounts of certain nutrients that are naturally abundant in animal ingredients.
This doesn't mean a cat's food can contain nothing but meat. Ingredients that provide dietary fiber can still have useful functions in a cat's diet. Appropriate fiber sources can help support normal digestion, stool quality, and gastrointestinal health. Certain types of fiber may also help move swallowed hair through the digestive tract, which can be beneficial for cats prone to hairballs. The important distinction is that cats have unique nutritional requirements associated with being obligate carnivores, so their food needs to be formulated specifically for them.
Do Dogs and Cats Like the Same Flavors?
Dogs and cats both tend to find savory, meat-based flavors appealing, but their sense of taste isn't identical. Cats are particularly responsive to compounds associated with animal proteins and amino acids. This makes meaty aromas and savory flavors especially attractive to many cats.
Dogs also tend to enjoy meat-based flavors, but unlike cats, dogs have functional sweet taste receptors and may show interest in some naturally sweet flavors. Cats are different because they lack a functional sweet taste receptor. In simple terms, cats don't perceive sweetness the way humans and dogs do. These differences help explain why foods designed for cats and dogs may have different flavor profiles even when they contain similar ingredients.
Essential Amino Acids
Protein is made up of amino acids, which the body uses for numerous biological functions. Some amino acids can be produced by the body, while others need to be obtained through food. These are known as essential amino acids.
Humans require nine essential amino acids:
- Histidine
- Isoleucine
- Leucine
- Lysine
- Methionine
- Phenylalanine
- Threonine
- Tryptophan
- Valine
Dogs require these nine plus arginine, giving them 10 essential amino acids that must be supplied through their diet; while cats have additional nutritional requirements. Cats require the same 10 essential amino acids recognized for dogs, and they also have a specific dietary requirement for taurine.
Taurine plays important roles in maintaining normal vision, heart function, reproduction, and other physiological functions. Cats cannot synthesize enough taurine to meet their needs, so an appropriate amount must be provided through their food. Animal tissues naturally contain taurine, and complete commercial cat foods are formulated to provide adequate levels. This is one major reason why cats should not be routinely fed food formulated specifically for dogs.
Do Cats Need More Protein Than Dogs?
In general, cats have higher dietary protein requirements than dogs. Because cats evolved as obligate carnivores, their metabolism is adapted to using protein and amino acids continuously for many physiological processes.
AAFCO nutrient profiles reflect the different nutritional requirements of dogs and cats. However, the required minimum depends on the animal's life stage, so one protein percentage should not be applied to every dog or cat.
Can Dogs Eat Cat Food?
If your dog steals a small amount of your cat's food occasionally, it generally isn't the same as making cat food part of the dog's regular diet. Cat food is specifically formulated around feline nutritional requirements and is often higher in protein and fat than many dog foods. Because the nutritional profiles are different, regularly replacing a dog's complete diet with cat food isn't recommended unless specifically directed by a veterinarian.