Pet Nutrition and the Unmeasured Owner Outcome: A Bidirectional Framework for Relational Value in Human-Animal Relationships.

The emotional benefits of pet ownership depend critically on the pet's physical, behavioural, and cognitive health-all of which can be improved by targeted nutritional interventions that may reduce pain, anxiety, problem behaviours, and cognitive decline. However, almost no studies have tested whether nutrition-induced behavioural improvements translate into measurable gains in owner emotional well-being or relationship satisfaction. It is important to note that the evidence base for cats remains considerably more limited than that for dogs, and many conclusions drawn from canine studies should be extrapolated to cats with caution. Furthermore, the human-animal relationship is bidirectional: owner psychology and feeding practices feed back to affect pet health. This review synthesises evidence across veterinary medicine, nutritional science, and human- animal interaction research to support a central thesis: that the relational value of pet ownership may be a function of pet health, may be modifiable by targeted nutrition, and is hypothesized to be embedded in bidirectional feedback loops that require dyadic interventions. The review explicitly distinguishes between evidence-supported findings and the proposed conceptual framework. The field now requires dyadic randomised controlled trials with co-primary outcomes for both pet and owner, plus precision stratification, pragmatic effectiveness studies, mechanistic biomarkers, and one health approaches. Closing this translational gap requires a coordinated research effort focused on designing dyadic interventions that measurably improve the welfare of both pets and their owners.