Department of Natural Resources and Environmental Science, University of Nevada, Reno, Reno, NV 89775, USA,
Veterinary Teaching Hospital, Louisiana State University, Baton Rouge, LA 70803, USA.
J Zoo Wildl Med. 2022 Jun;53(2):412-423. doi: 10.1638/2020-0168.
Noninvasive methods for measuring fat reserves in both captive and free-ranging animals are important for monitoring individual and population health, but chelonian anatomy and physiology present challenges to accurate measurements. Standard field-based methods for assessing body condition in Mojave desert tortoises () involve the qualitative body condition score, which relies on the apparent height of the temporalis muscle relative to the sagittal crest (in addition to other characteristics) and quantitative body condition indices that measure relative mass at size. However, it is unclear how these metrics relate to body fat reserves in this species. The aims of this study were to (1) describe the use of noninvasive computed tomography in measuring body fat volume of Mojave desert tortoises, (2) describe the location of fat reserves, (3) investigate relationships between fat reserves and body condition score and body condition index, and (4) explore whether relative temporalis muscle depth, measured via computed tomography, correlates with body condition score. Body condition scores were assessed for eight captive Mojave desert tortoises prior to euthanasia, and computed tomography was performed postmortem to quantify fat volume and measure temporalis muscle depth. At necropsy, the distribution of fat was documented. Fat volume calculated by computed tomography ranged from 2.83 to 145.38 cm (0.07-2.5% body volume). Neither qualitative body condition score nor quantitative body condition index was correlated with fat volume. Bladder content did not compromise body condition index. Body condition score was not correlated with relative temporalis muscle depth. Computed tomography is a noninvasive method for successfully identifying fat reserves and estimating total fat volume in Mojave desert tortoises. The lack of a relationship between computed tomography-determined metrics and commonly used body condition metrics indicates that computed tomography fills a critical gap in the health assessment tool kit for captive and free-ranging Mojave desert tortoises.
非侵入性方法来测量圈养和自由放养动物的脂肪储备对于监测个体和种群健康非常重要，但龟鳖类动物的解剖和生理学给准确测量带来了挑战。评估莫哈韦沙漠龟（）身体状况的标准现场方法包括定性身体状况评分，该评分依赖于颞肌相对于矢状嵴的表观高度（除其他特征外）和定量身体状况指数，这些指数测量相对于大小的相对质量。然而，目前尚不清楚这些指标与该物种的体脂储备有何关系。本研究的目的是：(1) 描述非侵入性计算机断层扫描在测量莫哈韦沙漠龟体脂肪量中的应用，(2) 描述脂肪储备的位置，(3) 研究脂肪储备与身体状况评分和身体状况指数之间的关系，以及 (4) 探索通过计算机断层扫描测量的相对颞肌深度是否与身体状况评分相关。在安乐死之前，对 8 只圈养的莫哈韦沙漠龟进行了身体状况评分评估，并进行了计算机断层扫描以量化脂肪量和测量颞肌深度。在尸检时，记录了脂肪的分布。通过计算机断层扫描计算的脂肪体积范围为 2.83 至 145.38 cm（0.07-2.5% 体重）。定性身体状况评分和定量身体状况指数均与脂肪量无关。膀胱内容物不影响身体状况指数。身体状况评分与相对颞肌深度无关。计算机断层扫描是一种成功识别莫哈韦沙漠龟脂肪储备并估计总脂肪量的非侵入性方法。计算机断层扫描确定的指标与常用的身体状况指标之间缺乏关系表明，计算机断层扫描在评估圈养和自由放养的莫哈韦沙漠龟的健康方面填补了一个关键空白。
