Table 4_Objective measurements of skinfold thickness with a caliper show a significant relationship to total body fat percentage in dogs.docx

ObjectiveNew clinical evaluation methods for estimation of total body fat percentage (BF%) in dogs are needed. The methods should be objective and reliable for accurate assessment of body composition status and to improve prevention and treatment of obesity. The aims of the study were therefore to investigate the intra- and inter-observer reliability of objective measurements of skinfold thickness with a caliper and to explore the relationship of skinfold thickness to dual-energy X-ray absorptiometry (DEXA) BF% in dogs.
MethodsTwenty-three carcasses of dogs euthanatized for reasons unrelated to the study were evaluated for body condition score (BCS), bodyweight, skinfold thickness, and DEXA BF%. The results from the latter were taken as gold standard for BF% measurement. The cohort consisted of 14 different breeds, aged ≥1 year. Objective measurements of skinfold thickness were collected in triplicate by two blinded observers at the locations of the “dorsal neck,” “axillar rib,” and “lumbar back.” Statistical analyses explored intra-class correlation coefficients (ICCs) and relationships by linear models and generalized additive models (GAMs).
ResultsThe dogs had a BCS of 2–9/9, a bodyweight of 2–52 kilograms, and a BF% of 6.4–74.7 percent. Objective measurements of skinfold thickness showed high intra- (range 0.991–0.993) and inter- (range 0.937–0.977) observer reliability at all locations. The skinfold thickness of the “axillar rib” in interaction with bodyweight within a spline (p = 0.0001), plus the “dorsal neck” as a linear variable (p = 0.0004), explained 73.4% of the variation in DEXA BF%. The BF% of small-sized dogs were over- and under-predicted by the prediction equation to a larger extent than for dogs of larger sizes. Due to the interaction with bodyweight, a slight variation in the low measurement values of the skinfold thickness corresponded to a large variation in DEXA BF%.
ConclusionObjective measurements of skinfold thickness could be assessed with high reliability with a caliper and showed a significant non-linear relationship to DEXA BF%. Longitudinal clinical studies with larger cohorts of small-, medium-, and large-sized dogs of different breeds and BCS are warranted, to evaluate the caliper device for its potential to follow changes of BF% over time. Objective measurements of skinfold thickness may in the future be practically implemented in nutritional assessments of dogs.

【研究目的】目前亟需开发用于评估犬体总脂肪百分比（BF%）的客观临床检测方法。此类方法需具备良好的客观性与可靠性，以实现机体成分状态的精准评估，进而优化犬肥胖症的预防与治疗方案。为此，本研究旨在两方面开展工作：一是探究使用卡尺（caliper）进行皮褶厚度（skinfold thickness）客观测量的观察者内部与观察者间信度；二是分析犬皮褶厚度与双能X射线吸收测定法（DEXA）测得BF%之间的关联。

【研究方法】本研究纳入23只因与本研究无关原因实施安乐死的犬只，对其体况评分（BCS）、体重、皮褶厚度及DEXA测得BF%进行检测，其中DEXA测得BF%作为BF%检测的金标准（gold standard）。研究队列涵盖14个不同品种，受试犬年龄均≥1岁。由2名实施盲法的观察者在“颈背侧”“腋肋部”“腰背部”三个测量部位，对皮褶厚度进行三次重复的客观测量。统计学分析采用组内相关系数（ICCs），并通过线性模型与广义加性模型（GAMs）探究变量间的关联关系。

【研究结果】受试犬的体况评分为2~9/9分，体重范围为2~52 kg，BF%范围为6.4%~74.7%。所有测量部位的皮褶厚度客观测量均表现出较高的观察者内部信度（组内相关系数范围0.991~0.993）与观察者间信度（组内相关系数范围0.937~0.977）。结合体重的样条（spline）交互项分析显示，“腋肋部”皮褶厚度与“颈背侧”皮褶厚度的线性项可解释DEXA测得BF%73.4%的变异量（p=0.0001，p=0.0004）。相较于大型犬，小型犬的BF%预测值与实际值的偏差程度更高。由于体重的交互效应，皮褶厚度测量值的小幅波动会对应DEXA测得BF%的较大变化。

【研究结论】使用卡尺开展皮褶厚度的客观测量具备较高的可靠性，且其与DEXA测得BF%存在显著的非线性关联。未来需开展针对不同品种、体况评分的大、中、小型犬队列的纵向临床研究，以评估该卡尺设备用于追踪犬BF%随时间变化的潜力。皮褶厚度的客观测量有望在未来应用于犬的营养评估实践中。