狗狗牵引绳怎么上下？
狗脖子上的那个带子，叫做项圈（neck collar）或者脖圈（neck band）。 它是一类牵引带的统称。 在美国兽医协会的网站上，是这样介绍项圈的： Neck collars are the most commonly used dog training aids in some countries. These devices have a strap that goes around your pet’s neck and another piece of rope or chain that passes through an adjustable loop at one end to go over your dog's head， then under his/her chin， then back up behind their neck to connect with the other end of the strap on your side， which is held in place by a buckle. (The end without a buckle must be longer than the end you use when putting it on， so that the collar fits comfortably; if not， it will chafe！) When not in use， this collar should hang down below your dog's elbows. Neck collars are adjustable for appropriate size. Collars can also be made with short或long leashes to allow more control by the handler. In general， these types of collars are very safe provided proper care is taken in their use. However， they can cause injury if not worn correctly because if your dog suddenly pulls away from you while wearing such a collar， he could jerk out of reach both the rope or chain connecting him to you as well as the buckle which keeps hold of the part of the collar behind him. Neck collars may also restrict breathing or make dogs feel uncomfortable. If there is any chance that your dog will be unable to breathe easily using this device， contact your veterinarian before using it. Neck collars come in all kinds of materials， shapes， sizes， colors——and prices！ Some dogs seem to like them， others find them uncomfortable or even frightening. The decision whether to purchase one depends entirely upon your dog and its response to various training situations. Your vet can help determine what type might work best for you and your dog.
在中文网上搜“项圈”可以找到很多关于使用项圈的帖子了，我就不抄过来了。这里重点说一下为什么要用项圈，什么情况下该用什么项圈吧。 我个人认为如果不用项圈，而改用皮带的话会更容易造成狗狗脱缰。因为皮带有可能会滑出牵引环，而且皮带会缠绕到狗狗脚上，导致它们在跑的时候很难挣脱。但是，如果你一定要用皮带，那么在购买时千万要买有防滑功能的牵引环哦~
至于为什么不能用狗链子呢……这主要和狗链子的设计有关。一般的狗链子中间是有一个锁孔的，这个锁孔的设计是为了防止主人松开手的同时让狗狗也松开嘴从而让狗狗自己挣脱开。可是这样一来当宠物狗遇到紧急情况时就会很难挣脱开了。
另外一点就是狗链子比牵引环要长很多。所以一般情况在遛狗时都会把牵引环扣在狗狗脖子上，而把狗链子放在腿