Does quantity equal quality? Source of protein influences American dog owner purchasing decisions more than the quantity of protein in the absence of marketing claims.

Protein is the most expensive macronutrient worldwide, yet protein-related claims like "high protein" or "protein #1 ingredient" strongly influence dog food purchases. Little is known about how dog owners define protein quality (PQ) and how this knowledge shapes purchasing decisions. This study investigated how perceptions of dietary protein translate from personal to dog feeding habits, the level of PQ knowledge among dog owners, and whether protein source or amount has a greater influence on dog food choice. A 60-question survey was distributed to dog owners across the United States using Qualtrics (Utah, USA) (n = 691). Each respondent answered 12 choice experiment questions in which dog food options varied by protein amount (20%, 35%), protein source (peas, chicken, chicken meal), and price ($80, $95, $110). Descriptive statistics were analyzed in SPSS Statistics (Version 29, IBM Corp.), and a multinomial logit model in STATA (Version BE) was used for choice experiment analysis, with significance set at P < 0.05. Chicken had the greatest influence on purchasing choice, followed by chicken meal, and 35% protein, compared to a baseline diet of 20% protein and peas (P < 0.001). The majority (30%) of respondents believed PQ was parallel to quantity, while only 18% could correctly define PQ as the ability of an ingredient to meet the indispensable amino acid requirements of an individual. For respondents who correctly defined PQ, all protein sources positively influenced choice, while greater protein quantity negatively influenced choice (P < 0.001). Ultimately, protein source, not amount, drives purchasing behavior in the absence of protein-related claims on dog food.