Short answer
For walking, especially a dog that pulls, a harness: the PDSA says "We recommend walking your dog on a harness if they pull - this will help prevent them from hurting their neck."1 But in the UK your dog still needs a collar with your name and address in public, with some exceptions2, so most owners use both.
What UK bodies say
This article answers one question from our guide to dog harness types.
The PDSA says: "We recommend walking your dog on a harness if they pull - this will help prevent them from hurting their neck."1
Battersea says: "A good harness should avoid pressure on your dog's neck and allow free shoulder movement. Look for a Y-shaped front for comfort."3
The RSPCA says: "Walk your dog on a harness rather than a collar and lead, to avoid putting pressure on their neck and help them breathe easier."4
What the research says
A 2020 study by Carter, McNally and Roshier tested seven collars and a slip lead on a model of a dog's neck, not on live dogs. It found: "Collars exerted a pressure of between 83 kPa and 832 kPa", and "No single collar tested provided a pressure considered low enough to mitigate the risk of injury when pulling on the lead."5
Remember this was a model of a neck, not live dogs, so it tells us about pressure, not about injuries in real dogs.
A 2024 study by Johnson and Wynne walked 23 dogs on a martingale collar, a front-connection harness and two prong-style collars. Pulling was significantly lower on the front-connection harness (and on both prong collars) than on the martingale collar, with no significant difference among those three, and the authors found no clear evidence of poorer welfare on any of them. They caution against generalising from a small study6.
We don't suggest prong collars. The RSPCA says: "Prong collars are designed to cause pain or discomfort to the animal to reduce or stop them from pulling on their lead," and "Research has shown that aversive training techniques, like prong collars, can cause pain and distress and can compromise dog welfare."7
Why your dog still needs a collar
The Control of Dogs Order 1992 says every dog "while in a highway or in a place of public resort shall wear a collar with the name and address of the owner inscribed on the collar or on a plate or badge attached to it"2. There are some exceptions, for example for certain working dogs.
So it's rarely "harness or collar". It's usually a harness for the lead and a collar for the ID tag. For collar fit, see puppy collar size and fit.
Harness vs collar at a glance
| Harness | Collar | |
|---|---|---|
| Lead pressure | A good harness avoids pressure on the neck3 | On the neck |
| For a dog that pulls | Recommended by the PDSA1 | Pressure on the neck5 |
| Flat-faced breeds | Advised by the RSPCA, PDSA and Royal Kennel Club4,8,9 | Advised against for walking |
| ID tag in public | Not a substitute | Required, with some exceptions2 |
What to avoid
The PDSA also says: "Don't use anything that is painful for your dog or restricts their movement (such as a choke collar)."1
Choosing and fitting a harness
If you're switching to a harness, choose one with a Y-shaped front that leaves the shoulders free3. Then read how should a dog harness fit? and, if your dog pulls, front-clip or back-clip harness?
Breed harness guides
Every breed fits a harness a little differently. These guides cover the sizes in each brand, how to measure that breed, and the styles that suit it.
- Labrador Retriever harness sizeSizes by brand, measuring and fit
- Cocker Spaniel harness sizeSizes by brand, measuring and fit
- Beagle harness sizeSizes by brand, measuring and fit
- Jack Russell Terrier harness sizeSizes by brand, measuring and fit
Find your dog's harness size All breeds
Questions
Is a harness better than a collar?
Do collars hurt dogs' necks?
A 2020 study on a model neck (not live dogs) found that no collar tested kept pressure low enough to mitigate the risk of injury when pulling5.
Can my dog wear just a harness?
Not in a public place, unless an exception applies: the law requires a collar with the owner's name and address on it or on an attached plate or badge2.