Most dogs wear down their nails through activity. If they are not worn down naturally, however, they can become extremely long and damage carpets and upholstery. Excessively long nails can splay the toes and interfere with traction by preventing the foot pads from making contact with the ground. Long nails should be trimmed.
Nails are also trimmed to prepare a dog for show. If trimming is done twice a month, the quick (the bundle of nerves and blood vessels inside the nail) will recede toward the base of the nail and the nail will remain permanently shorter.
Dogs with dewclaws must have these nails looked at frequently. Dewclaws are remnants of fifth toes and are found high on the inside of each foot. In many breeds the dewclaws are removed shortly after birth. In other breeds, such as Briards and Great Pyrenees, the presence of dewclaws is required by the breed standard. These nails do not contact the ground and thus can grow around in a circle and pierce the skin. Dewclaws should be trimmed regularly. This is particularly true for dogs with dewclaws on the rear legs. If you have a puppy with dewclaws, it is important to get her used to having them trimmed, even though trimming may not yet be necessary.
Some nail clippers for dogs have two cutting edges, while others of the guillotine type have one. Either type is satisfactory. Nail clippers designed for humans do not work well because a dog’s nails are not flat the way a person’s are.
Begin by lifting the dog’s paw and extending the nail. Identify the quick (the pink part running down the center), which contains the nerves and blood vessels. If the nails are white, it’s easy to see the quick. Be sure to trim the nail in front of (but close to) the quick. When using a guillotine cutter, the blade should slice upward from the underside of the nail. If the nails are dark and the quick is invisible, a good rule is to cut the nails parallel to the toe pads, so that the nails just clear the floor.
If you accidentally cut into the quick, the dog will feel a brief moment of pain and the nail will begin to bleed. Hold pressure over the end of the nail with a cotton ball. The blood will clot in a few minutes. If bleeding persists, pack with styptic powder or use a styptic pencil. In a pinch, cornstarch will also do.
To use a Dremel tool, you need to put on a sanding drum and carefully pull any hair away from the nail you are working on. Then carefully hold the tool against the nail with a slight pressure, removing just a small amount if you cannot see the quick. Do not push the sanding drum against the foot, just hold it lightly against the surface of the nail. You need to be careful that the tool is not getting warm and heating your dog’s toe.
Do not trim back into the quick. Rather, follow the guideline about trimming nails parallel to the toe pads.
source: http://pets.webmd.com/dogs/guide/trimming-dog-nails-dewclaws
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