Clipping Toenails
Most dog owners would rank clipping toenails right up there with root canals and tooth extractions. And with good reason. Most dogs hate getting their toenails clipped, and rotties are no exception. What makes matters worse is that rotties have black toenails, which makes it impossible to see the quick. Consequently, inexperienced rottie owners accidentally cut the quick, which firmly cements a pro-found hatred of toenail clipping within their rottie's mind.
What is the quick?
The quick is the blood supply for the nail. It is very sensitive and if cut will bleed a lot. If you accidentally cut into it, not only will you have a mess, but you'll also have a rottweiler that will never want you to touch his feet again.
There are two types of nail clippers: the guillotine variety and the scissors type. Both are good if they have sharp blades. The scissors type sometimes has a safety stop that helps gauge a safe amount of nail to snip off.
Handling His Feet
Your rottie may not wish you to handle his feet at first. In this case, get him used to your holding his feet by picking up one foot at a time and letting it go. Give him a treat when you're done. Practice this often, and slowly increase the amount of time you hold his foot. When you finally can hold his foot long enough to clip his nails, try it.
Trimming Your Rottie's Toenails
Hold your rottie's foot and snip off a small portion of the nail. If you have a safety stop, use that as a guide. Clip each toenail, and don't forget to clip the dewclaws if he has them. Give him a treat afterward. You'll need to clip his toenails once a week.
If there's a trick to snipping black toenails, it is taking only a little bit at a time. Stop if the nail feels spongy or if your rottie acts uncomfortable. If you do hit the quick, pack the nail with styptic powder to stop the bleeding. Another device, which costs more than the clippers, is a nail grinder. Dogs that dislike the clippers sometimes tolerate the grinder far better.
The quick grows as the nail grows. If you don't cut your rottie's toenails, the quick will be correspondingly long. The way to reduce the toenail and shrink the quick is to keep the nails cut short just before the quick and let the quick recede. After a few days, the quick will have receded and you can trim some more nail.
If you're unsure about clipping your rottie's nails, ask your vet or groomer to show you how to do it.

