Sizing a harness for a deep-chested dog

Size a deep-chested dog by its chest and nothing else. Greyhounds, Whippets, Dobermans and Dachshunds carry far more ribcage than their weight suggests, so any chart's weight column will point them at a harness that is too small — sometimes one that cannot close at all. Measure the girth, choose the size that puts it nearer the middle of a range, and look for a design whose neck and girth adjust separately.

What "deep-chested" means for a harness

A deep-chested dog has a ribcage that drops low between the front legs, a narrow waist behind it, and often a head and neck that are slim for the size of the chest. Three things follow:

• The chest is large for the weight. Charts that print weight beside each size assume an average build. A lean, deep dog sits above that average, so its weight lands a size or more below its chest.
• The neck is small for the chest. A harness whose neck opening grows with the size can fit the ribcage and still sit loose round the neck — the gap a dog backs out through.
• The waist is narrow. With nothing behind the ribs to hold it, a two-strap harness that is even slightly loose slides backwards and off. This is why sighthounds have a reputation as escape artists.

Going by weight: a worked example

Take a dog that weighs 14kg and measures 68cm round the chest — a lean, deep-chested build. Here is what six charts that print weight say, first by weight and then by the tape:

Chart	By 14kg	By 68cm chest
PetSafe Easy Walk 3 in 1	Small (48.3–61cm)	Medium — the Small stops 7cm short and cannot close
Julius-K9 IDC Powerharness	Mini or 0	0 — the Mini (49–67cm) stops 1cm short
Wonder Walker No-Pull	Small	Small at the very loose end (85%), or Medium near the middle
Kurgo Tru-Fit Smart	Medium	Medium at the loose end (88%), or Large
PetSafe Easy Walk	Medium	Medium, near the middle
PawSafe Steady+Style	M	M, a third of the way in

At two brands, going by weight can buy a harness that will not go round the dog. At two more it buys one strapped out to its limit, with nothing left to give and the girth strap free to slide. Only at two does the weight happen to land on a sensible size. The tape gets the right answer at all six.

The other six charts on this site print no weight at all, which removes the temptation. Where a chart's weight and girth disagree, the girth wins, every time.

Measuring a deep chest

• Measure at the deepest point of the ribcage, which on these dogs is further back and lower than people expect — just behind the elbows, where the chest is at its lowest.
• Keep the tape level. On a dog whose chest drops steeply, a tape that rides forward under the chest and back over the spine measures a diagonal and reads long.
• Snug, not tight, with the dog standing square. A thin-coated dog has nothing to compress, so a tight tape reads small almost at once.

The full routine, and ways round a dog that will not stand still, are on how to measure.

Choosing the size

For most deep-chested adults, the size that puts the chest measurement nearest the middle of its range is the right one: it leaves adjustment both ways and keeps the girth strap from being let out to the end where it can travel. If two sizes are close, prefer the smaller — escapes are a too-loose failure, and a lean dog has no waist to stop a loose harness sliding back. Between two sizes covers the trade-off.

The breed pages show where each breed's typical weight falls on every chart, with a warning on the breeds where weight is least reliable: Whippet, Greyhound, Doberman, Dachshund and Miniature Dachshund. Use them to shortlist, then let the tape decide.

Choosing the shape

Size is half of it. A chart cannot tell you the other half, so check the product listing for these:

• Neck and girth that adjust independently. On a dog with a slim neck and a big chest, you need to close the neck without letting the girth out, and the other way round.
• A Y-shaped front that sits on the breastbone and leaves the shoulders free, rather than a strap straight across the front of the chest.
• For sighthounds, a third strap around the narrow waist. Greyhounds, Whippets, Salukis and Italian Greyhounds have heads and shoulders narrower than their ribcage; a two-strap harness tight enough to be safe on them is usually too tight to be comfortable. These are sold as three-strap or escape-resistant harnesses.
• A girth strap that sits on the ribs, not right behind the elbow. On a deep chest the strap wants to sit slightly further back, and a design that forces it into the armpit will rub.

Fitting it

Two fingers laid flat under every strap with the dog standing, then slide the girth strap forwards: on a deep-chested dog it must stop against the elbows, not climb the ribcage. Finish with a gentle backwards pull from the back of the harness — the dog should move with it. If the front climbs or the girth strap slides, tighten it or go down a size. Why dogs back out of harnesses explains why that slide is the failure that matters.