**Background:** The global pet food industry is growing rapidly, with sales reaching US$114.8 billion in 2021 and projected to surpass US$156.9 billion by 2026. Cat and dog foods account for over 96% of these sales. While palatability is recognized as a crucial factor for product success and repurchase, research and development still relies heavily on traditional consumption-based testing methods that measure how much food is eaten without explaining why differences occur at a fundamental ingredient level. This review aims to synthesize knowledge on feeding behavior, nutritional requirements, pet food formats, ingredients, and palatability assessment methods for cats and dogs, with a focus on identifying gaps in understanding the drivers of palatability.
**Methods:** This is a narrative review that synthesizes published literature on pet food palatability, covering: (1) domestication history and feeding behaviors of cats and dogs; (2) species-specific nutrient requirements including protein, amino acids (taurine, arginine), vitamins (A, niacin), minerals (calcium, phosphorus), and fats; (3) macronutrient selection patterns; (4) pet food types (dry, wet, semi-moist) and their ingredients; (5) traditional palatability testing methods (one-bowl and two-bowl tests, behavioral assessments); (6) known palatability drivers including taste receptors, meat and meat by-product palatability, specific nutrients, and physical properties of food; and (7) emerging industry trends.
**Key Results:** The review identifies several critical findings from the literature: (1) Cats have a higher minimum protein requirement than dogs (26% vs 18% on a dry matter basis), with protein requirements increasing to 30% for growing stages and 22.5% for lactation. (2) Cats lack the dioxygenase enzyme to convert β-carotene to vitamin A, requiring preformed dietary vitamin A, with a safe upper limit of 333,300 IU/kg. (3) Cats have an upregulated picolinic carboxylase pathway that breaks down niacin faster than it is produced, necessitating dietary niacin from meat. (4) Using geometric analysis, cats select macronutrients at 52% protein, 36% fat, and 12% carbohydrate based on metabolizable energy, while dogs select 30% protein, 63% fat, and 7% carbohydrate. (5) Cats display a carbohydrate ceiling effect of approximately 300 kJ/day (72 kcal/day). (6) Cats lack functional sweet taste receptors but have abundant amino acid taste receptors, showing preference for 'sweet' amino acids (L-proline, L-cysteine, L-ornithine, L-lysine, L-histidine, L-alanine) and rejection of 'bitter' amino acids (L-arginine, L-isoleucine, L-phenylalanine, L-tryptophan). (7) The Calcium Sensing Receptor (CaSR) has been identified as a putative kokumi taste receptor in cats, responding to various L-amino acids, peptides, and glutathione derivatives. (8) Traditional two-bowl testing typically uses 8-10 animals over 5-6 days or 20 animals over 2-4 days to obtain 50-60 observations, with a trained panel of 8 cats for 2 hours over 5 days being a common protocol. (9) Dietary fiber content along with calcium, phosphorus, and ash have been identified as constituents that negatively affect food preference in cats. (10) Cats prefer food served at body temperature (37°C) compared to room temperature (21°C), with chilled food (6°C) being least preferred. (11) Preliminary research shows liver is the most palatable offal and mechanically deboned meat (MDM) the least palatable within beef and lamb, with a consistent preference for lamb over equivalent beef offal.
**Clinical Implications:** Understanding the fundamental drivers of palatability in cats and dogs has significant implications for pet food formulation and animal health. The review highlights that current industry practices focus on consumption metrics without identifying the specific nutritional components driving intake. This gap is particularly important for cats as obligate carnivores, where palatability directly impacts nutritional adequacy and health outcomes. The identification of specific amino acid preferences, the role of the CaSR kokumi receptor, and the negative impact of certain minerals (calcium, phosphorus) and fiber on palatability provide actionable targets for formulation. The finding that wet foods more closely match cats' target macronutrient intake (high protein, moderate fat, low carbohydrate) compared to dry foods (which can contain up to 40% carbohydrates) has implications for obesity prevention and chronic disease management, particularly chronic kidney disease where high phosphorus levels (>3.0 or 3.6 g/1000 kcal) may lead to kidney damage. The review also notes that Maillard reaction products increase palatability but decrease protein digestibility, presenting a trade-off for manufacturers. The authors conclude that integrating metabolomics with traditional palatability testing could unlock knowledge about the specific compounds responsible for driving food preference, enabling more precise formulation of palatable and nutritionally optimal pet foods.