Radiographic characteristics of cranial cruciate ligament disease in small- and large-breed dogs

To compare the severity of radiographic features of cranial cruciate ligament disease (CCLD) in 123 small (≤15 kg) and 125 large (>15 kg) breed dogs and to determine whether body size influenced the proportion of positive radiographic signs in cases with equivocal clinical instability.

A retrospective cross-sectional study was conducted on 298 stifles (149 small breed, 149 large breed) with surgically confirmed CCLD via arthroscopy or arthrotomy. Standard caudocranial and mediolateral radiographs of the stifle were scored by a board-certified radiologist blinded to dog size using a validated system assessing global osteoarthritis (OA), joint effusion, general osteophytosis, patellar osteophytosis, trochlear groove osteophytosis, tibial sclerosis and intra-articular mineralisation. Multivariable ordinal and binary logistic regression was performed with dog size as the primary predictor, adjusting for age, sex, chronicity, tibial plateau angle (TPA), meniscal injury and body condition score (BCS). A subgroup with equivocal or negative cranial drawer (n = 112) was then assessed separately. A stratified analysis assessing joint effusion was performed between groups with and without nonsteroidal anti-inflammatory drugs (NSAIDs).

Large dogs scored higher across all parameters (P < 0.001) bar tibial sclerosis. Adjusted odds ratios (ORs) were highest for trochlear groove osteophytosis (OR = 4.33, 95% confidence interval [CI] 2.21-8.47, P < 0.001), patella osteophytosis (OR = 2.54, 95% CI 1.33-4.85, P = 0.005) and global OA (OR = 5.85, 95% CI 3.55-9.64, P < 0.001). These differences were consistent in cases with a negative or equivocal cranial drawer test. There was no effect of recent NSAID use on the differential scoring of joint effusion between dogs.

Large-breed dogs exhibited more severe radiographic OA at the time of CCLD diagnosis.

Clinicians should consider the dog's size when assessing radiographs for suspected CCLD. This is most useful in cases of negative or equivocal stifle instability.