中国有句俗语，叫“狗改不了吃屎”，比喻恶习不改，劣性难移。吃屎确实是狗狗的一种天性。但一旦狗狗形成吃大便的习惯，真的会令主人非常困扰（试想像狗狗吃过大便后来亲你）。

研究发现，23％的狗至少吃过一次屎，而某些品种的狗更容易吃粪便，谢德兰牧犬食粪的概率最高(41％)。

A 2018 study published in the Journal of Veterinary Medicine and Science surveyed about 1,400 dog owners in the United States and found that 23% of dogs had eaten poop at least once and 16% were "frequent" poop eaters who ate poop at least six times over the course of the study.
2018年发表在《兽医学与科学杂志》上的一项研究调查了美国约1400名狗主人，发现23％的狗至少吃过一次屎，16％的狗在研究期间吃过至少六次。

那么狗真的改不了吃屎吗？狗为什么要吃屎吗？该如何阻止这个习惯呢？兽医学家们给出了解释。

狗为什么吃屎，这对它们有害吗？

Dogs eating their own poop — a condition called coprophagia — is considered a natural behavior. It's not a form of attention seeking or a result of nutritional deficiencies. Instead, veterinarians think coprophagia in dogs stems from their evolutionary connection to wolves, as wolf mothers eat their pups' poop to avoid exposing them to intestinal parasites.
狗吃自己的粪便，被称为食粪症，这种行为是一种自然行为。狗吃粪便不是为了寻求关注或缺乏营养。相反，兽医认为狗的食粪症源自它们与狼在基因上的联系，因为母狼会吃幼崽的粪便以避免小狼接触到肠道寄生虫。

Wolves will eat the feces of their young during the first three years of life, veterinarian Dr. Nicholas Dodman, president of the nonprofit Center for Canine Behavior Studies and a professor emeritus at Tufts University Cummings School of Veterinary Medicine, told Live Science. In fresh poop, the eggs of various parasites are not yet infectious. If let to sit, the parasites can grow and infect the pups if ingested.
兽医、非营利性机构“犬行为研究中心”主席、塔夫茨大学医学院荣休教授尼古拉斯·多德曼博士告诉《生活科学》，狼在幼崽出生后的三年会吃掉它们的粪便。在新鲜的粪便中，各种寄生虫的卵还不具传染性。如果放置一段时间，这些寄生虫就会生长并在幼崽摄入后感染它们。

"You're more likely to survive if you're healthy than if you're … ridden with worms," he said.
他说：“和身上满是寄生虫的小狼相比，健康的小狼更有可能存活下来。”

Even though domesticated dogs have come a long way from the wolf den, "I think the important takeaway is that it's no risk; it's just disgusting to us because of our upbringing," Dodman said.
尽管驯养的狗已经和狼有很大区别，但多德曼说，“重要的是，狗吃粪便没有危害；人类觉得这很恶心是因为我们的认知”。

哪些狗狗吃粪便？

Certain dog breeds might be more prone to coprophagy, the 2018 study found. Shetland sheepdogs had the highest rate of coprophagia (41%), while no poodles were reported as poop-eating. A dog's sex is also linked to its tendency to eat poop. A 2019 study conducted by Dodman and colleagues and published in the Journal of Veterinary Behavior looked at the behavior of over 4,000 dogs. They found 11% of male dogs engaged in poop eating, while 16% of female dogs did. Interestingly, coprographia was twice as common in dogs that were neutered than in dogs that were not neutered.
该研究发现，某些品种的狗更容易吃粪便。谢德兰牧犬食粪的概率最高(41％)，而研究称没有发现贵宾犬吃粪便。狗的性别也与其吃粪便的倾向有关。多德曼和同事们于2019年进行的一项研究发现，在4000多只狗中，11％的公狗会吃大便，而16％的母狗会。有趣的是，绝育的狗食粪的概率是未绝育的狗的两倍。

As for why dogs eat the poop of other animals, like cats and rabbits … it's just tasty, Melissa Bain, a veterinary behaviorist at UC Davis Veterinary Medicine and co-author of the 2018 study, told Live Science. Cats eat a high-protein diet, so their stool might be particularly delectable to dogs, she said.
至于为什么狗会吃其他动物的屎，比如猫和兔子……它们只是觉得好吃，加州大学戴维斯分校兽医行为学家、2018年研究的合著者梅丽莎·贝恩告诉《生活科学》。猫吃高蛋白饮食，所以它们的粪便对狗来说可能特别美味。

该如何让狗停止吃粪便？

Even if it's not harmful to your pooch, there's no denying that people are repulsed by poop eating. So is there anything you can do to get your dog to stop?
即使吃粪便对你的狗没有害处，人们也无法否认食粪症令人反感。那么有没有办法让你的狗停止吃大便呢？

Several commercial products are marketed for getting dogs to stop eating poop, but these have not been proved effective. Bain's 2018 study looked at 11 food additives marketed for coprophagia and found that the effectiveness of these products ranged from zero to 2%. "Don't waste your money," she said.
市场上有几种产品宣传可以让狗停止吃屎，但这些产品的有效性还没有得到证明。贝恩的2018年研究调查了11种市场上用于治疗食粪症的食品添加剂，发现这些产品的有效性从零到2％不等。“别浪费你的钱，”她说。

The internet is full of home remedies to stop coprophagia, like adding breath mints or pineapple to a dog's food. But there's no evidence that this works for most dogs, either. "You'll probably find someone who says they think it worked in their dog," Dodman said. "But basically, it's not a strategy that you can rely on."
互联网上充斥着阻止狗吃粪便的方法，比如在狗粮中添加薄荷糖或菠萝。但也没有证据表明这对大多数狗都有效。多德曼说：“你可能会发现有人说他们认为这对他们的狗有效。但基本上，这不是一种可靠的策略。”

In his veterinary practice, Dodman has tried diet changes that alter the consistency of a dog's poop and stop coprophagia. 
多德曼在实践中，尝试过通过改变狗的饮食，以改变狗粪便的稠度，从而阻止食粪症。

"If you change it to be less palatable, if you can imagine that, and more … dry and cardboardy, that seems to work," Dodman said, although he has not tested this in clinical trials.
多德曼说：“如果把粪便变得不那么可口，可以想象一下，变得更……干燥粗硬，这似乎是有效的，这似乎是有效的。”尽管他还没有在临床试验中测试过这一点。

What does work? "Clean it up," Bain said, and give the dog no time to munch on its feces. Some owners may try sprinkling Tabasco sauce or cayenne pepper on a dog's poop to deter them from eating it. "But if you're going to do that," Dodman said, "you might as well pick it up."
什么方法最有效？贝恩回答，“把粪便清理干净”，不给狗吃屎的时间。有的狗主人可能会尝试在狗屎上撒辣椒酱或辣椒粉。多德曼说： “但如果你要这么做，还不如及时清理。”