Canids are a morphological and physiological diverse group of animals, with the most diversity found within one species, the domestic dog. Underlying observed morphological differences, there must also be differences at other levels of organization that could lead to elucidating aging rates and life span disparities between wild and domestic canids. Furthermore, small-breed dogs live significantly longer lives than large-breed dogs, while having higher mass-specific metabolic rates and faster growth rates. At the cellular level, a clear mechanism underlying whole animal traits has not been fully elucidated, although oxidative stress has been implicated as a potential culprit of the disparate life spans of domestic dogs. We used plasma and red blood cells from known aged domestic dogs and wild canids, and measured several oxidative stress variables: total antioxidant capacity (TAC), lipid damage, and enzymatic activities of catalase, superoxide dismutase, and glutathione peroxidase (GPx). We used phylogenetically informed general linear mixed models and nonphylogenetically corrected linear regression analysis. We found that lipid damage increases with age in domestic dogs, whereas TAC increases with age and TAC and GPx activity increases as a function of age/maximum life span in wild canids, which may partly explain longer potential life spans in wolves. As body mass increases, TAC and GPx activity increase in wild canids, but not domestic dogs, highlighting that artificial selection may have decreased antioxidant capacity in domestic dogs. We found that small-breed dogs have significantly higher circulating lipid damage compared with large-breed dogs, concomitant to their high mass-specific metabolism and higher growth rates, but in opposition to their long life spans.

中文翻译：

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犬科动物的寿命和体重差异令人费解：家犬和野犬科动物血液中氧化应激的系统发育比较。

犬科动物是一组形态和生理上各异的动物，其中一种是家养犬，种类最多。在观察到的形态学差异的基础上，在组织的其他层次上也必须存在差异，这可能导致阐明野生犬科和家养犬科动物的衰老率和寿命差异。此外，小型犬比大型犬的寿命明显更长，同时具有更高的特定质量代谢率和更快的生长速率。在细胞水平上，虽然已经将氧化应激作为家犬不同寿命的罪魁祸首，但尚未完全阐明整个动物性状的基本机制。我们使用了已知的老年犬和野生犬的血浆和红细胞，并测量了一些氧化应激变量：总抗氧化能力（TAC），脂质损伤以及过氧化氢酶，超氧化物歧化酶和谷胱甘肽过氧化物酶（GPx）的酶活性。我们使用了系统发育知识的一般线性混合模型和非系统发育校正的线性回归分析。我们发现，家犬的脂质损伤随年龄增长而增加，而TAC随年龄增长而增加，而TAC和GPx活性随年龄/最大寿命增加而增加，这在一定程度上可以解释狼的潜在寿命更长。随着体重的增加，野生犬科动物的TAC和GPx活性增加，但家犬却没有，这表明人工选择可能降低了家犬的抗氧化能力。我们发现，与大型犬相比，小型犬的循环脂质损伤明显更高，