Evaluation of the use of muscle condition score and ultrasonographic measurements for assessment of muscle mass in dogs.

OBJECTIVE: To evaluate repeatability and reproducibility of muscle condition score (MCS) in dogs with various degrees of muscle loss; to compare MCS, muscle ultrasonographic measurements, and quantitative magnetic resonance (QMR) measurements; and to identify cutoff values for ultrasonographic measurements of muscle that can be used to identify dogs with cachexia and sarcopenia.

ANIMALS: 40 dogs of various age, body condition score (BCS), and MCS.

PROCEDURES: A prospective cross-sectional study was conducted. Body weight, BCS, QMR measurements, thoracic radiographic measurements, and muscle ultrasonographic measurements were assessed once in each dog. The MCS for each dog was assessed 3 separate times by 4 separate raters.

RESULTS: For the MCS, overall κ for interrater agreement was 0.50 and overall κ for intrarater agreement ranged from 0.59 to 0.77. For both interrater and intrarater agreement, κ coefficients were higher for dogs with normal muscle mass and severe muscle loss and lower for dogs with mild and moderate muscle loss. The MCS was significantly correlated with age ( r = -0.62), vertebral epaxial muscle score (VEMS; r = 0.71), forelimb epaxial muscle score (FLEMS; r = 0.58), and BCS ( r = 0.73), and VEMS was significantly correlated ( r = 0.84) with FLEMS. Cutoff values for identification of mild muscle loss determined by use of VEMS and FLEMS were 1.124 and 1.666, respectively.

CONCLUSIONS AND CLINICAL RELEVANCE: MCS had substantial repeatability and moderate reproducibility for assessment of muscle mass in dogs. Prospective studies of MCS, VEMS, and FLEMS for assessment of muscle mass in dogs are warranted.