# Phenotypic Differences in Inflammatory, Metabolic, and Biochemical Biomarkers in Dogs with Osteoarthritis According to Body Condition and Sex

## TL;DR

This study finds that osteoarthritis in dogs has different biological profiles depending on body condition, with thin dogs showing more inflammation and obese dogs showing more metabolic changes.

## Contribution

The study identifies distinct systemic biomarker profiles in canine osteoarthritis based on body condition, revealing biologically distinct phenotypes.

## Key findings

- Thin dogs with osteoarthritis showed higher interleukin-1 beta concentrations compared to healthy controls.
- Obese dogs with osteoarthritis exhibited metabolic changes like increased gamma-glutamyl transferase and cholesterol.
- Biomarker differences were more influenced by body condition than sex.

## Abstract

Osteoarthritis (OA) is a common joint disease in dogs that causes pain and reduced mobility. Although it primarily affects the joints, it can also influence the whole body through changes in inflammation and metabolism. Body condition, such as being overweight or underweight, as well as sex, may shape these systemic effects. The aim of this study was to evaluate blood markers related to inflammation, metabolism, organ function, and cartilage breakdown in dogs with OA, comparing thin and obese animals with healthy dogs. Blood samples from client-owned dogs were analyzed using statistical models that allowed fair comparisons between groups. Dogs with OA showed distinct biological patterns depending on body condition. Thin dogs tended to show higher inflammatory activity, whereas obese dogs mainly exhibited changes related to metabolic processes. Several commonly studied markers showed little or no difference between groups. These findings indicate that osteoarthritis in dogs is not a single uniform condition but includes different biological profiles, which may help improve understanding and clinical management of the disease.

Osteoarthritis (OA) in dogs is increasingly recognized as a condition with systemic inflammatory and metabolic components, potentially influenced by body condition and sex. This study aimed to characterize phenotypic differences in circulating inflammatory, metabolic, and biochemical biomarkers in dogs with OA according to body condition and sex. In this cross-sectional study, client-owned dogs were classified as healthy controls, thin dogs with OA (TOA), or obese dogs with OA (OOA). Circulating cytokines, adipokines, cartilage degradation markers, and routine biochemical parameters were measured in blood samples, including interleukin-1 beta, interleukin-4, interleukin-10, adiponectin, C-terminal telopeptide of type II collagen, and standard metabolic and hepatic markers. Data were analyzed using linear models fitted on log-transformed values, with group and sex as fixed effects, complemented by adjusted and sensitivity analyses. TOA dogs showed significantly higher interleukin-1 beta concentrations compared with controls (multiplicative effect 1.39, 95% confidence interval 1.05–1.82), indicating increased systemic inflammatory activity. In contrast, OOA dogs exhibited predominantly metabolic-associated alterations, including higher gamma-glutamyl transferase activity (multiplicative effect 1.22, 95% confidence interval 1.03–1.46) and higher cholesterol concentrations (multiplicative effect 1.22, 95% confidence interval 1.03–1.46). Several other biomarkers showed no clear group-related differences. Overall, these findings demonstrate that systemic biomarker profiles in canine OA vary primarily according to body condition, with secondary sex-related patterns, supporting the existence of biologically distinct OA phenotypes relevant for future diagnostic and therapeutic strategies.