Characteristics of Nutrition and Metabolism in Dogs and Cats

Abstract

Domestic dogsDogand catsCat have evolved differentially in some aspects of nutritionNutrition, metabolismMetabolism, chemical sensing, and feedingFeedingbehaviorBehavior. The dogsDog have adapted to omnivorous dietsDietcontainingTaurine taurine-abundant meat andStarch starch-rich plant ingredientsIngredient. By contrast, domestic catsCatmust consumeAnimalanimal-sourced foodsFoodfor survivalSurvival, growthGrowth, and developmentDevelopment. Both dogsDogand catsCatsynthesizeVitamin vitamin C and many amino acids (AAs, such as alanine, asparagine, aspartate, glutamate, glutamine, glycine, proline, and serine), but have a limited ability to form de novo arginineArginineand vitaminVitamin D3. Compared with dogsDog, catsCat have greater endogenousEndogenousnitrogenNitrogen losses and higher dietary requirementsRequirement for AAs (particularly arginineArginine, taurineTaurine, and tyrosineTyrosine), B-complex vitaminsNiacin (niacin, thiamin, folateFolate, and biotinBiotin), and cholineCholine; exhibit greater rates of gluconeogenesisGluconeogenesis; are less sensitive to AA imbalances and antagonism; are more capable of concentrating urineUrine through renal reabsorption of waterWater; and cannot tolerate high levels of dietary starchStarch due to limited pancreatic α-amylase activity. In addition, dogsDog can form sufficient taurineTaurinefrom cysteineCysteine(for most breedsBreeds); arachidonic acidArachidonic acidfrom linoleic acidLinoleic acid; eicosapentaenoic acid and docosahexaenoic acidDocosahexaenoic acid from α-linolenic acid; all-trans-retinol from β-carotene; and niacinNiacinfrom tryptophanTryptophan. These synthetic pathways, however, are either absent or limited in all catsCat due to (a) no or low activities of key enzymesEnzyme (including pyrroline-5-carboxylate synthase, cysteineCysteinedioxygenaseDioxygenase, ∆6-desaturase, β-carotene dioxygenaseDioxygenase, and quinolinate phosphoribosyltransferase) and (b) diversion of intermediates to other metabolic pathways. DogsDog can thrive on one large mealMeal daily, select high-fatFat over low-fat dietsDiet, and consume sweet substances. By contrast, catsCat eat more frequently during light and dark periods, select high-proteinProtein over low-protein dietsDiet, refuse dryFoodfoodDry food, enjoy a consistent dietDiet, and cannot tasteTaste sweetness. This knowledge guides the feedingFeeding and care of dogsDogand catsCat, as well as the manufacturing of their foodsFood. As abundant sources of essentialEssentialnutrients, animal-derivedAnimalfoodstuffsFoodstuff play important roles in optimizing the growthGrowth, developmentDevelopment, and healthHealth of the companionCompanionanimalsAnimal.