狗狗绝育的好处和坏处（上），养狗狗的妈妈们一定要仔细斟酌后再决定！互相分享给大家参考！
以下论文来自维基百科，翻译：蓝炯。
Long-Term Health Risks and Benefits Associated with Spay / Neuter in Dogs
母犬卵巢摘除手术和公犬阉割手术[译者按: 以下统称绝育手术]的长期健康风险及益处
Laura J. Sanborn, M.S./劳拉 J. 桑伯恩，外科硕士
May 14, 2007/2007年5月14日
Precis 摘要 (略)
INTRODUCTION 引言
Dog owners in America are frequently advised to spay/neuter their dogs for health reasons. A number of health benefits are cited, yet evidence is usually not cited to support the alleged health benefits.
在美国，宠物犬主常常会收到让他们的狗狗做绝育的建议，理由是为了狗狗的健康。虽然在建议绝育时会列出一大堆绝育对健康的好处，但通常却并不会同时列出证据来支持所宣称的好处。
When discussing the health impacts of spay/neuter, health risks are often not mentioned. At times, some risks are mentioned, but the most severe risks usually are not.
当人们在讨论绝育对健康的影响时，对于绝育会带来的健康风险却往往闭口不谈。虽然偶尔也会提到一些风险，但绝大多数严重的风险却通常不会提及。
This article is an attempt to summarize the long-term health risks and benefits associated with spay/neuter in dogs that can be found in the veterinary medical literature. This article will not discuss the impact of spay/neuter on population control, or the impact of spay/neuter on behavior.
本文尝试对于在兽医医学文献中可以找到的，和母犬/公犬绝育相关的长期健康风险和益处进行总结。对绝育会对犬只数量控制或者犬的行为方面的影响本文不做讨论。
Nearly all of the health risks and benefits summarized in this article are findings from retrospective epidemiological research studies of dogs, which examine potential associations by looking backwards in time. A few are from prospective research studies, which examine potential associations by looking forward in time.
本文所总结的几乎所有健康风险和益处均为犬的流行病学回溯性研究发现。这些研究通过回顾过去来考察潜在的关联关系。还有少量的为前瞻性研究，通过展望将来考察潜在的关联关系。
SUMMARY 概要
An objective reading of the veterinary medical literature reveals a complex situation with respect to the long term health risks and benefits associated with spay/neuter in dogs. The evidence shows that spay/neuter correlates with both positive AND adverse health effects in dogs. It also suggests how much we really do not yet understand about this subject.
对兽医医学文献客观的阅读揭示了和母犬/公犬绝育手术相关的长期健康风险和益处。证据显示绝育既会给犬带来正面的健康影响，同时也会带来负面的健康影响。它同时也让我们意识到我们在这个问题上认识的匮乏。
On balance, it appears that no compelling case can be made for neutering most male dogs, especially immature male dogs, in order to prevent future health problems. The number of health problems associated with neutering may exceed the associated health benefits in most cases.
总之，似乎无法举出令人信服的案例可以说明对大多数公犬，尤其是发育未成熟的公犬，进行绝育是为了预防将来的健康问题。在大多数案例中，公犬绝育所引起的健康问题可能要超过所带来的健康益处。
On the positive side, neutering male dogs
公犬绝育手术的正面影响：
? eliminates the small risk (probably <1%) of dying from testicular cancer
? reduces the risk of non-cancerous prostate disorders
? reduces the risk of perianal fistulas
? may possibly reduce the risk of diabetes (data inconclusive)
On the negative side, neutering male dogs
公犬绝育手术的负面影响：
? if done before 1 year of age, significantly increases the risk of osteosarcoma (bone cancer); this is a common cancer in medium/large and larger breeds with a poor prognosis.
如果在1周岁之前手术,会显著增加患骨肉瘤(即骨癌)的风险。骨肉瘤是在中型和大型犬中的一种常见癌症，预后很差。
? increases the risk of cardiac hemangiosarcoma by a factor of 1.6
患心脏血管瘤的风险会增加1.6倍。
? triples the risk of hypothyroidism
患甲状腺功能减退的风险增加到3倍。
? increases the risk of progressive geriatric cognitive impairment
增加患老年认知障碍的风险。
? triples the risk of obesity, a common health problem in dogs with many associated health problems
患肥胖症的风险增加到3倍。肥胖是犬的常见健康问题，会引发很多其它健康问题。
? quadruples the small risk (<0.6%) of prostate cancer
患前列腺癌的风险增加到4倍（犬患前列腺癌的几率很小，为<0.6%）。
? doubles the small risk (<1%) of urinary tract cancers
患尿路癌的风险增加到2倍（犬患尿路癌的几率也很小，为<1%）
? increases the risk of orthopedic disorders
增加患骨科疾病的风险。
? increases the risk of adverse reactions to vaccinations
增加发生免疫不良反应的风险。
For female dogs, the situation is more complex. The number of health benefits associated with spaying may exceed the associated health problems in some (not all) cases. On balance, whether spaying improves the odds of overall good health or degrades them probably depends on the age of the female dog and the relative risk of various diseases in the different breeds.
On the positive side, spaying female dogs
母犬绝育手术的正面影响：
? if done before 2.5 years of age, greatly reduces the risk of mammary tumors, the most common malignant tumors in female dogs
如果在2.5周岁前实施手术会极大地降低患乳腺肿瘤的风险。乳腺肿瘤是母犬中最常见的恶性肿瘤。
? nearly eliminates the risk of pyometra, which otherwise would affect about 23% of intact female dogs; pyometra kills about 1% of intact female dogs
几乎可以消除患子宫蓄脓的风险。而未实施绝育手术的母犬患子宫蓄脓的几率大约为23%。有大约1%的未绝育母犬因患子宫蓄脓而死亡。
? reduces the risk of perianal fistulas
降低患肛周瘘管的风险。
? removes the very small risk (_0.5%) from uterine, cervical, and ovarian tumors
消除患子宫肿瘤，宫颈肿瘤以及卵巢肿瘤的风险（母犬患这类疾病的几率本身就很低，为0.5%）
On the negative side, spaying female dogs
母犬绝育手术的负面影响:
? if done before 1 year of age, significantly increases the risk of osteosarcoma (bone cancer); this is a common cancer in larger breeds with a poor prognosis
如果在1周岁前实施手术，会极大地增加患骨肉瘤（即骨癌）的风险。骨癌是较大型犬种中的常见癌，预后很差。
? increases the risk of splenic hemangiosarcoma by a factor of 2.2 and cardiac hemangiosarcoma by a factor of >5; this is a common cancer and major cause of death in some breeds
患脾脏血管瘤的风险增加到2.2倍，患心脏血管瘤的风险增加到>5倍。血管瘤是犬的常见癌症，是某些品种犬的主要死因。
? triples the risk of hypothyroidism
患甲状腺功能减退的风险增加到3倍。
? increases the risk of obesity by a factor of 1.6-2, a common health problem in dogs with many associated health problems
患肥胖症的风险增加到1.6-2倍。肥胖是犬的常见健康问题，会引发很多其它健康问题。
? causes urinary “spay incontinence” in 4-20% of female dogs
引起4-20%的母犬患“绝育尿失禁”症。
? increases the risk of persistent or recurring urinary tract infections by a factor of 3-4
患持续尿路感染或重复发生尿路感染的风险增加到3-4倍。
? increases the risk of recessed vulva, vaginal dermatitis, and vaginitis, especially for female dogs spayed before puberty
增加外阴凹陷，阴道性皮炎以及阴道炎的风险，尤其是对于在青春期之前做绝育手术的母犬。
? doubles the small risk (<1%) of urinary tract tumors
患尿路肿瘤的微小风险（<1%）增加至2倍。
? increases the risk of orthopedic disorders
增加患骨骼系统疾病的风险。
? increases the risk of adverse reactions to vaccinations
增加发生免疫不良反应的风险。
One thing is clear – much of the spay/neuter information that is available to the public is unbalanced and contains claims that are exaggerated or unsupported by evidence. Rather than helping to educate pet owners, much of it has contributed to common misunderstandings about the health risks and benefits associated of spay/neuter in dogs.
有一点非常清楚-公众所获得的关于犬绝育的信息是不完全的，包含了许多夸大其词或者没有事实依据的论断。与其说这些信息起到了教育宠物主人的作用，不如说有许多信息导致了一些常见错误观念，使人们错误地认识和绝育手术相关的健康风险和益处。
The traditional spay/neuter age of six months as well as the modern practice of pediatric spay/neuter appear to predispose dogs to health risks that could otherwise be avoided by waiting until the dog is physically mature, or perhaps in the case of many male dogs, foregoing it altogether unless medically necessary.
传统的绝育时机（6个月）以及现代在幼儿时期就进行绝育的做法有可能使犬更容易罹患疾病，而这些疾病原本是可以避免的，如果1）等犬生理成熟之后再绝育；或者2）对于众多的公犬来说，干脆不做绝育，等到医疗必要时再做。
The balance of long-term health risks and benefits of spay/neuter will vary from one dog to the next. Breed, age, and gender are variables that must be taken into consideration in conjunction with non-medical factors for each individual dog. Across-the-board recommendations for all pet dogs do not appear to be supportable from findings in the veterinary medical literature.
绝育所带来的长期的健康风险和益处视不同的个体而不同。犬种，年龄以及性别都是可变因素，需作为每一只狗的非医学因素考虑在内。兽医医学文献的研究结果不支持一刀切地对所有宠物犬做出关于绝育方面的建议。
FINDINGS FROM STUDIES
研究发现
This section summarizes the diseases or conditions that have been studied with respect to spay/neuter in dogs.
本章节总结了针对绝育犬只进行的疾病或症状的研究。
Complications from Spay/Neuter Surgery
绝育手术并发症
All surgery incurs some risk of complications, including adverse reactions to anesthesia, hemorrhage, inflammation, infection, etc. Complications include only immediate and near term impacts that are clearly linked to the surgery, not to longer term impacts that can only be assessed by research studies.
任何手术都会有一定的风险，包括对麻药的不良反应，出血，发炎，感染等。并发症仅包括明确由手术引起的直接的和近期的影响，而不包括那些只能通过研究才能确定的长期的影响。
At one veterinary teaching hospital where complications were tracked, the rates of intraoperative, postoperative and total complications were 6.3%, 14.1% and 20.6%, respectively as a result of spaying female dogs1. Other studies found a rate of total complications from spaying of 17.7%2 and 23%3. A study of Canadian veterinary private practitioners found complication rates of 22% and 19% for spaying female dogs and neutering male dogs, respectively4.
有一家兽医教学医院通过对并发症的跟踪发现，接受绝育手术的母犬在术中，术后以及总体并发症的发生率分别为6.3%，14.1%和20.6%。其它一些研究发现母犬绝育手术并发症总体发生率为17.7%和23%。一项关于加拿大私立兽医诊所的调查发现绝育母犬和公犬的并发症发生率分别为22%和19%。
Serious complications such as infections, abscesses, rupture of the surgical wound, and chewed out sutures were reported at a 1- 4% frequency, with spay and castration surgeries accounting for 90% and 10% of these complications, respectively.4
The death rate due to complications from spay/neuter is low, at around 0.1%2.
严重并发症，例如感染，脓肿，手术伤口破裂，以及缝线咬出的发生率据报告为1-4%,其中母犬绝育手术和公犬绝育手术发生这些并发症的分别占90%和10%。
在犬的绝育手术中因并发症而死亡的比例很低，大约为0.1%。
Prostate Cancer 前列腺癌
Much of the spay/neuter information available to the public asserts that neutering will reduce or eliminate the risk that male dogs develop prostate cancer. This would not be an unreasonable assumption, given that prostate cancer in humans is linked to testosterone. But the evidence in dogs does not support this claim.
公众可以获得的许多关于母犬/公犬绝育的信息宣称绝育可以降低或者消除公犬患前列腺癌的风险。鉴于人类的前列腺癌的确和睾丸素相关，因此这可能并非是一个不合理的假设。但我们从犬类身上所获得的证据却并不支持这个观点。
In fact, the strongest evidence suggests just the opposite.
事实上，最有力的证据却恰恰支持相反的观点。
There have been several conflicting epidemiological studies over the years that found either an increased risk or a decreased risk of prostate cancer in neutered dogs. These studies did not utilize control populations, rendering these results at best difficult to interpret. This may partially explain the conflicting results.
近年来，有一些相互冲突的流行病学研究发现，在绝育公犬中前列腺癌的发生有上升或者下降的几率。这些研究没有利用对照犬群，因此研究结果显得非常难以解释。这可能就是出现矛盾结果的部分原因。
More recently, two retrospective studies were conducted that did utilize control populations. One of these studies involved a dog population in Europe5 and the other involved a dog population in America6. Both studies found that neutered male dogs have a four times higher risk of prostate cancer than intact dogs.
更近的一些时候，有人利用对照犬群进行了两项回溯性的研究。其中一项研究涵盖了欧洲的一些犬群，而另一项研究则涵盖了美国的一些犬群。两项研究均发现绝育公犬患前列腺癌的机率要比未绝育公犬高4倍。
Based on their results, the researchers suggest a cause-and-effect relationship: “this suggests that castration does not initiate the development of prostatic carcinoma in the dog, but does favor tumor progression”5 and also “Our study found that most canine prostate cancers are of ductal/urothelial origin….The relatively low incidence of prostate cancer in intact dogs may suggest that testicular hormones are in fact protective against ductal/urothelial prostatic carcinoma, or may have indirect effects on cancer development by changing the environment in the prostate.”6
根据研究结果，研究者认为其中的因果关系是这样的：“这说明去势手术虽然不会引发犬的前列腺癌，但确实会有利于肿瘤的生长”，以及“我们的研究发现绝大多数犬类前列腺癌为导管或者膀胱上皮原发性。。。。。。而未绝育公犬前列腺癌的低发率可能也提示我们事实上睾丸激素对于防止导管性前列腺癌/膀胱上皮性前列腺癌的发生是起到保护作用的。或者有可能因为改变了前列腺内的环境而对前列腺癌的生长有着间接的影响。”
This needs to be put in perspective. Unlike the situation in humans, prostate cancer is uncommon in dogs.
不过我们也需要客观地看待这个结论。和人类的情况不同，前列腺癌在犬类中很少发生。
Given an incidence of prostate cancer in dogs of less than 0.6% from necropsy studies7, it is difficult to see that the risk of prostate cancer should factor heavily into most neutering decisions. There is evidence for an increased risk of prostate cancer in at least one breed (Bouviers)5, though very little data so far to guide us in regards to other breeds.
根据尸检报告，犬类前列腺癌的发生率为不到0.6%。鉴于此，我们很难将前列腺癌的风险作为决定大多数公犬是否需要绝育的重要决定因素。虽然对于其它犬种目前的数据还很少，但至少在一个犬种（法兰德斯牧犬）中有证据表明前列腺癌的风险会增加。
Testicular Cancer 睾丸癌
Since the testicles are removed with neutering, castration removes any risk of testicular cancer (assuming the castration is done before cancer develops). This needs to be compared to the risk of testicular cancer in intact dogs.
由于在做绝育手术时已摘除睾丸，因此绝育同时也消除了任何患睾丸癌的风险（假设在实施手术前没有发生癌变）。这需要和未做绝育的公犬患睾丸癌的风险相对比。
Testicular tumors are not uncommon in older intact dogs, with a reported incidence of 7%8. However, the prognosis for treating testicular tumors is very good owing to a low rate of metastasis9, so testicular cancer is an uncommon cause of death in intact dogs. For example, in a Purdue University breed health survey of Golden Retrievers10, deaths due to testicular cancer were sufficiently infrequent that they did not appear on list of significant causes of "Years of Potential Life Lost for Veterinary Confirmed Cause of Death” even though 40% of GR males were intact. Furthermore, the GRs who were treated for testicular tumors had a
90.9% cure rate. This agrees well with other work that found 6-14% rates of metastasis for testicular tumors in dogs11.
未绝育老年公犬患睾丸癌并不少见，报告发生率为7%。但是，由于转移率很低，睾丸癌的治疗预后非常好，因此死于睾丸癌的未绝育公犬相当少。例如，美国普渡大学（Purdue University，一所历史悠久的研究性大学）所开展的一项关于金毛猎犬的调查显示，死于睾丸癌的病例非常少，因此睾丸癌没有被列入“兽医确认的死亡原因所造成的潜在损失寿命年限”表中的重要死亡原因，尽管有40%的雄性金毛猎犬没有做过绝育手术。此外，接受过睾丸癌治疗的金毛猎犬的治愈率为90.9%。这个结果和另外一项研究的发现相吻合。该项研究发现犬类睾丸癌的转移率为6-14%。
The high cure rate of testicular tumors combined with their frequency suggests that fewer than 1% of intact male dogs will die of testicular cancer.
睾丸癌的高治愈率及其发生率综合起来提示未绝育公犬死于睾丸癌的比例小于1%。
In summary, though it may be the most common reason why many advocate neutering young male dogs, the risk from life threatening testicular cancer is sufficiently low that neutering most male dogs to prevent it is difficult to justify.
总之，尽管这是许多人提倡在公犬幼年时就进行绝育的最常见理由，但睾丸癌威胁生命的风险却是相当低，因此以预防睾丸癌为理由对大多数公犬实施绝育手术难以立足。
An exception might be bilateral or unilateral cryptorchids, as testicles that are retained in the abdomen are13.6 times more likely to develop tumors than descended testicles12 and it is also more difficult to detect tumors in undescended testicles by routine physical examination.
双侧或单侧隐睾的公犬则是一个例外情况。因为滞留在腹腔的睾丸发生肿瘤的可能性比正常下降睾丸要高13.6倍，而且在常规体检中也更难检查出肿瘤。
Osteosarcoma (Bone Cancer) 骨肉瘤（骨癌）
A multi-breed case-control study of the risk factors for osteosarcoma found that spay/neutered dogs (males or females) had twice the risk of developing osteosarcoma as did intact dogs13.
一项在多品种犬群中开展的，针对骨肉瘤风险因素所进行的病例对照研究发现，绝育母犬/公犬发生骨肉瘤的几率是未绝育犬的2倍。
This risk was further studied in Rottweilers, a breed with a relatively high risk of osteosarcoma. This retrospective cohort study broke the risk down by age at spay/neuter, and found that the elevated risk of osteosarcoma is associated with spay/neuter of young dogs14. Rottweilers spayed/neutered before one year of age were 3.8 (males) or 3.1 (females) times more likely to develop osteosarcoma than intact dogs.
研究者还针对患骨肉瘤风险相对较高的罗威纳犬开展了调查。这项回溯性定群研究将风险按绝育年龄进行分类，结果发现幼犬绝育和患骨肉瘤几率骤升相关。在1周岁前绝育的罗威纳犬患骨肉瘤的几率比未绝育犬要高3.8倍（公犬）或者3.1倍（母犬）。
Indeed, the combination of breed risk and early spay/neuter meant that Rottweilers spayed/neutered before one year of age had a 28.4% (males) and 25.1% (females) risk of developing osteosarcoma. These results are consistent with the earlier multi-breed study13 but have an advantage of assessing risk as a function of age at neuter. A logical conclusion derived from combining the findings of these two studies is that spay/neuter of dogs before 1 year of age is associated with a significantly increased risk of osteosarcoma.
事实上，综合考虑犬种及早期绝育因素意味着在1周岁前绝育的罗威纳犬患骨肉瘤的几率分别为28.4%（公犬）和25.1%（母犬）。这些结果和前面所提到的多犬种研究是一致的，但优点是可以根据绝育年龄对患骨肉瘤的风险进行评估。从这两项研究中可以得出的一个符合逻辑的结论是：在1周岁之前绝育的公犬和母犬患骨肉瘤的风险会大大提高。
The researchers suggest a cause-and-effect relationship, as sex hormones are known to influence the maintenance of skeletal structure and mass, and also because their findings showed an inverse relationship between time of exposure to sex hormones and risk of osteosarcoma.14
研究者认为在绝育和骨肉瘤之间存在因果关系，因为性激素会对维护骨骼的结构和内容产生影响，而且他们的发现也显示了暴露在性激素下的时间长短和患骨肉瘤的几率成反比。
The risk of osteosarcoma increases with increasing breed size and especially height13. It is a common cause of death in medium/large, large, and giant breeds. Osteosarcoma is the third most common cause of death in Golden Retrievers10 and is even more common in larger breeds13.
患骨肉瘤的风险随犬种的增大，尤其是犬身高的增加而增加。骨肉瘤是中大型以及巨型犬种的常见死因。在金毛猎犬的常见死因中,骨肉瘤位居第三。而在更大型犬种的常见死因中，骨肉瘤的排名甚至还要靠前。
Given the poor prognosis of osteosarcoma and its frequency in many breeds, spay/neuter of immature dogs in the medium/large, large, and giant breeds is apparently associated with a significant and elevated risk of death due to osteosarcoma.
鉴于骨肉瘤的预后很差及其在许多犬种中的多发性，对中大型，大型以及巨型犬的未成熟犬进行绝育会明显导致因骨肉瘤而死亡的风险骤增。
Mammary Cancer (Breast Cancer) 乳腺肿瘤（乳房癌）
Mammary tumors are by far the most common tumors in intact female dogs, constituting some 53% of all malignant tumors in female dogs in a study of dogs in Norway15 where spaying is much less common than in the USA.
乳腺肿瘤是迄今为止在未绝育母犬中最常见的肿瘤。在挪威进行的一项犬类研究发现，乳腺癌占母犬所有恶性肿瘤的53%。而在挪威母犬做绝育的比例要远远低于美国。
50-60% of mammary tumors are malignant, for which there is a significant risk of metastasis16. Mammary tumors in dogs have been found to have estrogen receptors17, and the published research18 shows that the relative risk (odds ratio) that a female will develop mammary cancer compared to the risk in intact females is dependent on how many estrus cycles she experiences:
50-60%的乳腺肿瘤为恶性肿瘤，因为其发生转移的几率非常高。研究发现，犬的乳腺肿瘤中具有雌激素受体，而一项公开的研究显示和未绝育母犬的风险相比，母犬发生乳腺癌的相对风险（比值比）取决于母犬的发情次数：
# of estrus cycles before spay/绝育前发情次数 Odds Ratio/比值比
None/从未发情
1
2 or more/2次或以上
Intact/未绝育
The same data when categorized differently showed that the relative risk (odds ratio) that females will develop mammary cancer compared to the risk in intact females indicated that:
同样的数据以不同方式归类后显示和未绝育母犬的风险相比，母犬发生乳腺癌的相对风险（比值比）为：
Age at Spaying/绝育时犬龄
_ 29 months/29个月
_ 30 months/30个月
Intact/未绝育
Please note that these are RELATIVE risks. This study has been referenced elsewhere many times but the results have often been misrepresented as absolute risks.
请注意，上述数据为相对风险。该项研究曾被多次在别处引用，但研究结果却常常被错误地表示为绝对风险。
