There are several primary nutrients necessary in the diet of all dogs and cats: water, proteins, carbohydrates, fats, vitamins and minerals. Of these nutrients, proteins, carbohydrates and fats are the nutrients that are responsible for meeting the energy requirements of the dog or cat.
Types of Carbohydrates Found in the Diet of the Dog and Cat
Carbohydrates are divided into simple and complex carbohydrates. Simple carbohydrates include the monosaccharides and disaccharides, including glucose, sucrose and fructose.
Complex carbohydrates, or polysaccharides, are made up of long chains of simple sugars. Complex carbohydrates can be further separated into non-fiber and fiber complex carbohydrates. Fiber carbohydrates may be soluble or insoluble in nature.
Common sources of carbohydrates in dog and cat diets include grains such as corn, rice, barley, wheat and oats. These grains may be further processed by grinding, flaking and/or cooking to increase the palatability and the digestibility of the food source.
Carbohydrates and Energy Production in Canine and Feline Nutrition
Dietary carbohydrates enter the intestinal tract of the dog and cat, where enzymes produced in the pancreas and the small intestine digest them, converting them to monosaccharides (simple sugars such as glucose). These monosaccharides are absorbed into the bloodstream from the intestinal tract and are then distributed to the various tissues and organs within the body where they are either used to produce energy or stored for future use. The energy produced by the metabolism of carbohydrates is used to fuel the numerous biological and metabolic processes necessary to the normal functioning of the canine and feline body.
Both cats and dogs are capable of producing adequate amounts of glucose through the process of gluconeogenesis (the process of generating glucose from amino acids and glycerol). Therefore, carbohydrates are not considered to be essential dietary nutrients for dogs and cats even though glucose is metabolically necessary for dogs and cats.
Differences in Carbohydrate Metabolism and Nutrient Needs Between the Dog and the Cat
In the dog, the addition of carbohydrates to the diet can make it easier for the pet to meet the nutritional need for glucose without using protein as an energy source. This can spare protein for more important usages, such as maintaining and repairing body tissues, and result in a more efficient use of protein sources.
In the cat, the metabolism of proteins and carbohydrates are a bit different than in the dogs.
- Cats use hexokinase to metabolize glucose within individual cells, unlike the dog where glucokinase is used. Hexokinase works at a slower rate than glucokinase.
- Cats do not produce amylase in their saliva, as dogs do. Amylase is an enzyme that aids in breaking down carbohydrates.
- Cats have lower concentrations of the enzymes that digest carbohydrates than dogs.
- The process of gluconeogenesis in cats is always active, unlike in dogs. This difference in the rate of gluconeogenesis results in an increased protein requirement in the cat versus the dog.
Collectively, these differences mean that cats can convert protein to energy more efficiently than dogs. Therefore, the effect of the addition of moderate to large amounts of carbohydrates to the diet of the cat is less helpful than in the dog. However, the addition of small amounts of carbohydrates to the diet can still be beneficial for cats, resulting in more protein being available for tissue repair and maintenance.
The Role of Fiber as a Nutrient for Dogs and Cats
Fiber, a specific form of carbohydrate, should be present in all canine and feline diets. Fiber plays several roles.
- Soluble fibers, sometimes called prebiotics, are utilized by bacteria within the gastrointestinal tract of the dog and cat to produce short-chain fatty acids, which aids in promoting the growth of additional beneficial (or probiotic) bacteria and helps crowd out pathogenic (disease-producing) bacteria.
- Both soluble and insoluble fibers positively affect gastrointestinal motility and the passage of ingested food through the gastrointestinal tract.
- Dietary fiber also helps promote gastrointestinal health by collecting debris and dead cells that accumulate in the lumen of the gastrointestinal tract.
- In addition, dietary fiber plays a role in making the dog or cat feel satiated, meaning that the pet feels full after ingesting a meal with an adequate fiber content.
Common sources of fiber in the diet include cellulose, corn bran, beet pulp, rice hulls, soybean hulls and many others.
Other Roles of Carbohydrates in Canine and Feline Nutrition
Carbohydrates also aid in the production of many other substances needed by the body of the dog and cat by contributing carbon atoms and sugar molecules for their construction. These substances include non-essential amino acids, glycoproteins, glycolipids, lactase and Vitamin C.
While carbohydrates are considered to be non-essential dietary nutrients for dogs and cats, they nevertheless play an important metabolic role in canine and feline nutrition. Though dogs and cats are capable of producing adequate amounts of glucose to meet their energy needs through the metabolism of protein and fats, the addition of carbohydrates in the proper amounts can make protein metabolism much more efficient. In addition, carbohydrates in the form of both soluble and insoluble fiber play important roles in keeping both the canine and feline gastrointestinal tract healthy.
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