Click. Click. Click. You hear your dog coming down the hall before you see him. Most owners find that a homely sound. It is really a warning: if your dog's nails are too long, you hear them on the floor. And a dog walking on his nails stands less securely than a dog walking on his pads.

The link between nail length and slipping is one of the most underrated things in a house with an older dog. Here is how it works mechanically and what to do about it.

The click test takes five seconds

Let your dog stand upright on a hard floor. Get down on your knees and look at a front paw from the side. Does the tip of the nail touch the floor while he is standing still? Then it is too long.

The version without looking works just as well. Let your dog walk away across parquet or tiles and listen. A dog who clicks on the floor has nails making contact at a moment when they should not. At the right length there is a sliver of air between the nail tip and the ground as long as your dog is standing.

With older dogs this almost always goes wrong, for a dull reason: they walk shorter distances and less on tarmac. The nail no longer wears down by itself, while it keeps growing all the same.

What a nail that is too long does to the paw

Picture the toe as a small arch with the pad underneath. That pad is your dog's rubber: soft, slightly moist, built to grip. The nail is horn and grips nothing on a smooth floor.

As soon as the nail gets too long, it reaches the floor before the pad does. With every step the floor pushes the nail back into the toe. Three things happen at once:

• The toe tips upward. The front part of the pad lifts off the floor, leaving less rubber in contact.
• The weight shifts backwards. Your dog stands slightly more on his heels. That changes the angle of the wrist and the elbow. On the hind leg it changes the hock.
• The paw spreads differently. The toes cannot open as far on landing, so the support surface gets smaller.

On grass you notice none of this. There the nails dig into the ground and work like spikes. On parquet, laminate, tiles or vinyl the nail has nothing to sink into. It simply slides away, with the rest of the dog behind it.

Trimming nails gives grip back, though not on every floor

Trimming a dog's nails for grip is worthwhile and it is the cheapest intervention there is. Just do not expect a miracle on a mirror-smooth floor.

Short nails give your dog his full pad back. That pad needs friction to work. On a rug or on oiled wood there is friction enough. On polished tiles, high-gloss laminate or a freshly varnished floor the friction is so low that even a perfect pad slides through the moment your dog wants to accelerate or turn.

Here is how you tell the difference at home: a dog with overlong nails slides a bit everywhere, even on the mat. A dog with short nails only slides on the slickest patches. If it keeps going wrong on those patches, it is the floor and not the nail. Dog slipping on a slippery floor covers what works per surface.

How short is short enough

Inside the nail sits the quick: a small bundle of blood vessel and nerve. That is what you want to stay away from. On pale nails you can see it as a pink streak stopping before the tip. Cut a couple of millimetres below it.

On black nails you see nothing. Take off a thin slice at a time and look at the cut surface. As long as you see a dry, chalky core, you can carry on. Once a small grey or dark circle appears in the middle, you are close to the quick and you stop.

A file or a rotary grinder is easier than clippers for a lot of dogs. It goes slower, there is no snap, you feel better when to stop. Build it up in short sessions of thirty seconds per paw.

Do not forget the dewclaw, that little nail higher up on the inside of the leg. It never touches the ground, so it does not wear down at all. In older dogs it sometimes curls right back into the skin.

If the nails have been too long for months

Here comes the setback. If a nail stays long, the quick grows out with it. You cannot get back to the right length in one session without drawing blood and causing pain.

The answer is patience. Take a small piece off every week, a millimetre or two at most. The quick slowly retreats back toward the toe in response. Count on six to ten weeks before you reach a normal length. For dogs who fight it hard or nails already curling into the pad: have the first session done by the vet, under sedation if needed.

The combination that works best indoors

Short nails give the pad back. A sock puts grip underneath it. Those two do different jobs and they do not clash.

Our non-slip dog socks have silicone grip on both sides, so even if the sock turns a quarter of the way there is still grip under the paw. They also cover the nails right away, which prevents damage on parquet. There is more on that in dog scratching the hardwood floor.

One thing they do not replace: the trimming. A nail that is too long still pushes against the floor through a sock and keeps tipping the toe upward. So do the nails first and measure the size afterwards, because a dog with long nails easily measures half a centimetre too wide. How to do that properly is set out in measuring your dog's paw width. Still unsure about the size? The size calculator gives it in thirty seconds.

What you notice within two weeks

The sound goes first. The hallway falls quiet. After that many dogs take a slightly longer stride and dare to accelerate again on the floor where they used to tiptoe. That last part has as much to do with confidence as with friction. A dog who has slipped badly once will creep for months afterwards.

Is your dog still struggling to get up or to take the stairs despite short nails and grip under his paws? Then it is not the floor. Have the hips and knees checked by your vet.

Frequently asked questions

How often should I trim my dog's nails?

For most dogs every three to four weeks. Dogs who walk a lot on tarmac wear their nails down partly by themselves and need it less often. Older dogs and dogs who mostly walk on grass and indoors need it more often. The click test on a hard floor is a more reliable measure than the calendar.

I cut too far and it is bleeding. What now?

Stay calm, because a nail bleeds heavily yet rarely dangerously. Press a wad of kitchen paper firmly against the tip and hold it there for two to three minutes. Styptic powder or cornflour helps. If it has not stopped after ten minutes, call the vet.

Do dog socks help against nails that are too long?

They solve the consequences on the floor: no more scratches and more grip under the paw. The nail itself keeps growing and keeps pushing against the floor. So treat socks as an addition to trimming, not a replacement for it.