Evaluation of muscle mass and intramuscular fatty infiltration in dogs with hypercortisolism and their association with prognosis.

Abstract

BACKGROUND: Muscle atrophy and intramuscular fatty infiltration, as well as their association with prognosis, have not been quantified in dogs with spontaneous hypercortisolism (HC). OBJECTIVE: To quantitatively evaluate muscle atrophy and IM fatty infiltration in dogs with HC and determine their prognostic impact. ANIMALS: Fifty-three dogs with HC and 66 control dogs without HC. METHODS: Retrospective cohort study. Medical records and computed tomography images obtained between 2014 and 2021 were evaluated. Kaplan-Meier curves and log-rank tests were used to analyze the effect of muscle atrophy and IM fatty infiltration on the prognosis of dogs with HC. RESULTS: Dogs with HC showed lower visually measured cross-sectional area (VCSA) and cross-sectional area based on attenuation (HCSA) than control dogs (median [interquartile range {IQR}]: 50.3&#x2009;mm/mm [36.2-67.8] vs 66.7&#x2009;mm/mm [48.0-85.9]; P&#x2009;<&#x2009;.001; 30.4&#x2009;mm/mm [13.7-57.2] vs 54.8&#x2009;mm/mm [39.7-71.5]; P&#x2009;<&#x2009;.001, respectively). Dogs with HC had lower epaxial muscle attenuation (L3HU) than control dogs (median [IQR]: 21.2 Hounsfield [HU] [12.4-28.2] vs 33.2 HU [22.6-43.6]; P&#x2009;<&#x2009;.001). Dogs with HC with lower HCSA or L3HU had shorter survival (median [IQR]: 670&#x2009;days [222-673] vs 949&#x2009;days [788-1074], P&#x2009;<&#x2009;.01; 523&#x2009;days [132-670] vs 949&#x2009;days [756-1074], P&#x2009;<&#x2009;.01, respectively) but not lower VCSA (median [IQR]: 673&#x2009;days [132-788] vs 949&#x2009;days [523 to not applicable]; P&#x2009;=&#x2009;.30). CONCLUSION AND CLINICAL IMPORTANCE: Hypercortisolism in dogs causes muscle atrophy and IM fatty infiltration and is associated with poor prognosis.