Six signs a harness no longer fits

A harness rarely stops fitting all at once. A growing puppy's chest can change noticeably in a fortnight, an adult fills out or slims down, a winter coat comes in, the webbing softens. These are the six signs that it is time to re-measure — the first three mean it has become too small, the next two too big, and the last means the harness itself is finished.

It has become too small

1. The sliders are at the end of their straps

The clearest sign, and you can see it before the dog shows anything. If an adjuster has been let out to its last few centimetres of webbing and the harness still only just passes the two-finger check, there is nothing left to give. A puppy in that harness will outgrow it within weeks; a coat change will do it overnight.

2. Rubbing behind the front legs

Thinning fur, redness or a darker patch of skin just behind the elbows means the girth strap is sitting too far forward or pressing too hard. Both usually happen because the harness is too small for the chest and has been pulled forward to close. Broken skin is a reason to stop using the harness until it heals, and to ask a vet if it does not.

3. A shorter stride, or a dog that stops wanting to go

A strap across the front of the shoulders that has become tight stops the front legs reaching forward. The trot looks choppy in the harness and normal off-lead. Some dogs say it differently: they slow down, sit when the lead goes tight, or stand still while you put it on. If the reluctance is new and the harness is not, check the fit first.

It has become too big

4. It slides forward or swivels round

Dogs lose weight, get clipped short for summer, or simply finish growing into a lean adult. A harness that once fitted can then ride forward onto the shoulders under load, or rotate so the ring drifts to one side. Slide the girth strap forwards with your hand: if it travels several centimetres up the ribcage, a reversing dog can back out of it. Why dogs back out of harnesses has the three checks.

5. The front rides up to the throat

When the lead goes tight and the chest piece climbs towards the neck, or the dog coughs on a pull, the harness is loose enough to move. Tighten it if there is adjustment left; if the straps are already at their tightest, the dog has moved down a size.

The harness itself is finished

6. Frayed webbing, cracked buckles, a stretched strap

Fit is not the only thing that changes. Check the stitching at the lead ring, the edges of the webbing where it runs through sliders, and the plastic of every buckle. A buckle with a crack, or webbing that has gone thin and fuzzy where it rubs, is the point of failure on the day a dog lunges. Replace it regardless of fit. Chewed straps count — a chewed strap is weaker than it looks.

What to do when you see one

1. Re-measure the chest, standing, behind the front legs, snug against the coat (how). Do not go by the last measurement or the label on the old harness.
2. Look at where the new number sits in each brand's sizes, not just which size it falls in. A dog at the bottom of a size has room to grow; a dog at the top does not. The size finder shows the position for every chart at once.
3. Do not assume the next size up at the same brand is the answer. Sizes step differently at each brand — one maker's Medium can start where another's Large ends — and a different brand may put your dog nearer the middle.
4. Fit the new one properly — two flat fingers under every strap, and a girth strap that does not travel. How tight a harness should be goes through it step by step.

If the dog is still growing

Puppies are where this happens fastest. Re-measure every two to three weeks while they grow, and buy the size that puts today's measurement near the bottom of its range, so the growth goes into adjustment rather than into a new purchase. Saving your dog's measurements keeps the history in one place and, for a growing dog, works out roughly when the current size will run out.