Carbohydrates

February 18, 2026

Carbohydrates, along with proteins and fats, are macronutrients. Carbohydrates consist of three different elements: carbon, hydrogen, and oxygen. They are a source of energy and fiber for dogs and cats.

Carbohydrates can be divided into monosaccharides, disaccharides, oligosaccharides, and polysaccharides. Carbohydrates include sugars, starch, and dietary fiber. Monosaccharides include simple sugars such as glucose and fructose. Disaccharides are relatively simple sugars, including sucrose, for example. Both oligosaccharides and polysaccharides are considered slow-release carbohydrates. Polysaccharides can in turn be divided into two groups:

Digestible complex carbohydrates. These are complex carbohydrates that can be digested by endogenous enzymes; these carbohydrates are called starch.
Indigestible carbohydrates. These are carbohydrates that cannot be digested by digestive enzymes; these carbohydrates are known as dietary fiber. Dietary fiber cannot be digested but is fermented by bacteria in the intestines.

Although FEDIAF has not established a minimum amount of carbohydrates for dogs and cats, this nutrient does have positive aspects for these animals. Simple carbohydrates and starch can be used as energy in the form of glucose. Carbohydrates are not only used for energy; they are also a source of heat for the body, as metabolizing carbohydrates releases heat. The body can also store an excess of simple carbohydrates and starch in the form of glycogen or fat. Finally, certain products formed during metabolism may serve as building blocks for other nutrients.

The liver is essential for using carbohydrates as a source of energy. It is responsible for the synthesis, storage, conversion, and release of glucose for use by other organs. The highest concentration of glycogen is therefore found in the liver.

Carbohydrate digestion takes place throughout the body. In humans, digestion begins as soon as food enters the mouth. Human saliva contains amylase, which is needed to break down carbohydrates. This enzyme is not present in the saliva of dogs and cats. In these animals, carbohydrate digestion takes place primarily in the intestines. The pancreas secretes digestive enzymes that digest large amounts of starch and sugars.

As you have already read above, the body can use carbohydrates as a source of energy. Carbohydrates provide approximately 3.5 kcal per gram. Certain organs and tissues in the body, such as the brain, require glucose for energy. The body can obtain this glucose from glucogenic amino acids or from glycerol derived from fats.

If an animal’s diet contains insufficient carbohydrates, the body uses certain amino acids—which would normally be used for milk production, fetal growth, or muscle growth—for the synthesis of glucose.

Carbohydrates also play an important role in the processing of animal food, not just in supplying the body with energy. In this case, starch is an important component in the production of kibble. Starch gelatinization is crucial to the extrusion process. Without starch, it is not possible to produce a solid kibble.

Although FEDIAF has not provided guidelines regarding the amount of carbohydrates in dog and cat food, dogs’ need for this nutrient varies during pregnancy and lactation. This concerns a greater need for glucose. In this case, additional glucose is needed to support fetal growth and the synthesis of lactose in the mother’s milk. In general, the recommendation for a pregnant or lactating female dog is to provide food containing at least 23% carbohydrates.

Unlike dogs, cats do not need food containing more carbohydrates during pregnancy or lactation. These animals are perfectly capable of maintaining their blood glucose levels when fed a low-carbohydrate diet that is rich in protein. The pancreas of a cat also produces much less amylase than that of a dog. As a result, a cat’s body is less capable of metabolizing large amounts of simple carbohydrates.

The bodies of dogs and cats cannot break down all carbohydrates. Dietary fiber is one form of complex carbohydrate that the body cannot break down. This is because our four-legged companions do not produce the appropriate digestive enzymes to break down the bonds between the sugars in dietary fiber. As a result, the body cannot use dietary fiber as an energy source. However, this does not mean that fiber has no function in the bodies of our four-legged companions. On the contrary, dietary fiber has an important function in the intestines. Dietary fiber that the body cannot break down can be divided into two groups: fermentable dietary fiber and non-fermentable dietary fiber.

In the intestines, dietary fiber is fermented primarily by bacteria and yeasts. This fermentation process releases energy for the bacteria and the cells of the large intestine. This dietary fiber is known as prebiotic dietary fiber. These fibers support the growth of the microbiota, the total population of microorganisms in the intestines. In turn, the growth of the microbiota prevents harmful bacteria from colonizing the intestines.
Non-fermentable dietary fiber reaches the intestines unchanged. There, the fiber contributes to regular bowel movements and regulates fecal consistency. In addition, dietary fiber contains almost no calories, allowing it to add bulk and contribute to a feeling of satiety in pets that are prone to becoming overweight.

The bodies of dogs and cats produce the appropriate enzymes to digest various carbohydrates. The body breaks carbohydrates down into smaller sugar units, which can then be absorbed through the intestinal wall. There is one exception, however: lactose. Adult dogs and cats cannot adequately break down lactose, which can result in unpleasant gastrointestinal problems.