Although routine clipping of the nails of cats and dogs should not normally be necessary, there are circumstances under which it needs to be carried out.
In dogs, we usually only clip when there is overgrowth of the claws. This may occur in animals which, for whatever reason (arthritis, age, laziness(!), or not exercising regularly, or those which, because of the structure of their feet, have nails that do not wear normally. Some dew claws fit into this category, and can overgrow to the extent that they curl right back in on themselves. We also often need to clip - or at least blunt - those sharp little puppy claws which regularly rake their owners legs until the "not jumping up" lesson has been learnt.
In cats, claws are most commonly clipped in those older animals that do not as easily shed the outer layer of their claws, and regularly get themselves hooked into the carpet - or your best jersey! Of course there are those less than sociable felines whose owners require the claws to be clipped for their own protection.
However, before you take to your pet's claws with the clippers, you need to be aware that within the claw there is a bone surrounded by a "quick" which contains blood vessels and nerves (see diagram).
And if you inadvertently clip too short and cut the quick, your pet will let you know in no uncertain terms that it hurts and it will also bleed substantially, so care is needed.
With cat claws, and with those dogs that have transparent nails, the quick is easily visible - pink in colour - inside the nail, so is relatively simple to avoid. It is the dark coloured claws that are more difficult. Some of these have a natural hook on the end that starts where the quick ends. For those that don't, the best idea is to make successive small cuts up from the bottom of the nail making sure that you gradually increase the pressure on the clippers rather than cut straight through - this means that, when you do reach the quick, the dog can let you know you're there before you cut through.
The other thing to remember is that unlike human nails, cat and dog claws are three dimensional, so that human nail clippers will tend to squash the nail, causing damage above the cut. Use proper animal nail clippers to avoid this. The tips on those sharp little puppy claws can often more safely be filed off rather than clipped.
Virginia Williams and Bert Westera