Dog Harness and Collar Size Guide

How to measure

You need a soft tape, the kind from a sewing kit, and a dog standing square. A builder's tape does not bend round a ribcage and a piece of string marked and laid against a ruler is better than guessing. Two figures do the whole job.

• Neck girth. Around the base of the neck where a collar naturally sits, just in front of the shoulders. Not up under the jaw, where the neck is narrowest. Soft tape flat against the coat, snug but not tight. Do not add anything; a collar is bought by its adjustable range, and the harness neck strap only has to close to this figure.
• Chest girth. Around the widest part of the ribcage, just behind the front legs, with the tape level all the way round. Dog standing square, tape snug not tight. This is the measurement that decides the harness size, so take it twice and use the larger figure if they differ.

Pull the tape snug but not tight, and on a thick-coated dog press it through to the skin, because a harness sits on the dog and not on the fluff. Take the chest twice; if the two figures differ, use the larger one. Weight is a rough check only. Two dogs of the same weight can be a size apart at the chest, which is why a staffy and a kelpie of 18 kg do not wear the same harness.

Front clip, back clip and what no-pull means

A back-clip harness has the lead ring between the shoulder blades. It is the comfortable default for a dog that already walks on a loose lead: nothing rubs, the lead cannot tangle in the front legs and the dog can sniff without being steered. Its weakness is pulling power. A dog that pulls into a back clip is in the same position as a sled dog, and the whole body weight comes down the lead.

A front-clip harness has the ring on the chest plate. When the dog surges ahead the lead comes taut from the side, which turns the dog back towards you and takes that pulling power away. That is all a no-pull harness does: it steers, it does not train. The dog still has to learn that a loose lead is what moves the walk forward, and a front clip makes that lesson manageable rather than teaching it for you. Two things to avoid. A front ring on a badly fitted harness rubs the armpits and can pull the strap across the shoulder joint, so fit matters more with a front clip than a back one. And the harnesses that tighten under the armpits when the dog pulls work by discomfort, which is not the same thing as steering.

Most of the harnesses we rank carry both rings, so you can walk on the front ring while the pulling is being worked on and move to the back ring once it is not.

Harness or collar

Both, doing different jobs. The harness is for walking, and for any dog that pulls or has a delicate neck. That covers the toys, the flat-faced breeds whose airway is already narrow, the sighthounds and the dachshunds, and it covers every dog that has ever hit the end of a lead at speed. The collar is for the ID tag and the council registration tag, which the dog wears whether or not the harness is on, and it is where a GPS tracker usually clips. Keep the collar on, walk on the harness.

The RSPCA's position, in plain words, is that a well-fitted harness is kinder than a collar for a dog that pulls, because it spreads the load across the chest instead of concentrating it on the windpipe and the neck. The RSPCA does not recommend check chains or prong collars, and prong collars are a prohibited import in Australia and banned outright in Victoria. A front-clip harness does the same job without the pain, which is the point.

Fitting and the two-finger rule

Slide two fingers flat between the strap and the dog, everywhere the harness touches. Snug enough that the dog cannot back out of it, loose enough that the fingers slide without forcing.

• Chest strap two or three finger widths behind the front legs. Any closer and it rubs the armpit on every stride; the bald patch shows up within a fortnight.
• Neck strap at the base of the neck, not on the throat. On a Y-front harness the point of the Y sits on the breastbone.
• The back-out test. With the dog standing, take the lead and apply gentle backward pressure. A harness that slides forward over the shoulders is too loose, and a loose harness is the one a dog reverses out of on a busy road.
• Check it again after the first week, because new webbing settles; every week on a puppy; and after a big seasonal coat change on a husky, a pomeranian or a golden retriever.

Harnesses in the Australian summer

A padded harness that is a comfort in Hobart is a heat trap in Darwin. For most of the country, mesh or a light webbing harness suits summer better than thick neoprene, and a pale colour stays cooler than black webbing left in the sun. Take the harness off at home, because a dog that wears one all day in the heat gets a damp patch under the chest strap and that is where chafing starts. Rinse it in fresh water after the beach; salt stiffens webbing and the grit works like sandpaper. If you walk before seven and after six in the hot months, which is what the dog would choose, a padded harness is fine.