Hart Benjamin L, Hart Lynette A, Thigpen Abigail P, Willits Neil H
Department of Anatomy, Physiology and Cell Biology, School of Veterinary Medicine, University of California, Davis, Davis, CA, United States.
Department of Population Health and Reproduction, School of Veterinary Medicine, University of California, Davis, Davis, CA, United States.
Front Vet Sci. 2020 Jul 31;7:472. doi: 10.3389/fvets.2020.00472. eCollection 2020.
The early neutering of male and female dogs and its relationship to an increased risk of joint disorders and some cancers has recently become a concern, raising questions about the standard practice in the U.S. and much of Europe of neutering by 6 months of age. A noteworthy recent finding from this center is that there are major breed differences with small-dog breeds generally showing little vulnerability to neutering compared with breeds of larger body size. These findings on purebreds raise questions for dog owners and veterinarians about mixed-breed dogs. The purpose of this study was to examine a sample of mixed breed dogs of five weight categories using the same veterinary hospital database and diagnostic criteria for joint disorders and cancers as used in the newly published paper on 35 breeds and previous papers on the Golden Retriever, Labrador Retriever, and German Shepherd Dog. The weight categories were <10 kg (739 cases), 10-19 kg (546 cases), 20-29 kg (992 cases), 30-39 kg (604 cases), and over 40 kg (258 cases). Males and females were analyzed separately, as were various ages at neutering. The joint disorders examined were hip dysplasia, cranial cruciate ligament tear or rupture, and elbow dysplasia. The cancers were lymphoma, mast cell tumor, hemangiosarcoma, and osteosarcoma. There was no significant increased occurrence of one or more cancers, compared with intact dogs, in any weight category. However, in the three categories of dogs weighing 20 kg or more, neutering before 1 year generally was significantly associated with risks of one or more joint disorders above that of dogs left intact, commonly to 3 times the level of intact dogs, with sex differences in the degrees of joint disorders associated with neutering. For the dogs in the two weight categories <20 kg, no increased risks were found for joint disorders. This information can be useful to dog caregivers in deciding on the age at which to neuter specific dogs, and for veterinarians offering guidance to pet owners.
公犬和母犬的早期绝育及其与关节疾病和某些癌症风险增加的关系最近已成为一个关注点，引发了人们对美国和欧洲大部分地区在6个月龄时进行绝育的标准做法的质疑。该中心最近一项值得注意的发现是，存在主要品种差异，与体型较大的品种相比，小型犬品种通常对绝育的易感性较低。这些关于纯种犬的发现给狗狗主人和兽医带来了关于混血犬的问题。本研究的目的是使用与新发表的关于35个品种的论文以及之前关于金毛寻回犬、拉布拉多寻回犬和德国牧羊犬的论文中相同的兽医医院数据库和关节疾病及癌症诊断标准，对五个体重类别的混血犬样本进行研究。体重类别为<10千克（739例）、10 - 19千克（546例）、20 - 29千克（992例）、30 - 39千克（604例）和超过40千克（258例）。公犬和母犬分别进行分析，绝育时的不同年龄也分别进行分析。所检查的关节疾病包括髋关节发育不良、颅交叉韧带撕裂或断裂以及肘关节发育不良。癌症包括淋巴瘤、肥大细胞瘤、血管肉瘤和骨肉瘤。与未绝育的犬相比，在任何体重类别中，一种或多种癌症的发生率均未显著增加。然而，在体重20千克及以上的三类犬中，1岁前绝育通常与一种或多种关节疾病的风险显著相关，高于未绝育的犬，通常是未绝育犬的3倍，绝育相关的关节疾病程度存在性别差异。对于体重<20千克的两类犬，未发现关节疾病风险增加。这些信息对于狗狗护理人员决定为特定狗狗绝育的年龄以及为宠物主人提供指导的兽医可能有用。
