How Should a Dog Harness Fit? (Vet's Guide)

Dog harnesses are an alternative to dog collars that can be used for identification, dog walking, or training assistance. Due to safety concerns with dog collars, harnesses are preferred for certain breeds or dogs with certain medical conditions. Multiple types of harnesses are available, so owners should select the one most appropriate for their dog. Read on to learn more about harnesses and how to best fit one on your dog.

In This Article

How Should a Harness Fit on a Dog?

There are four things to keep in mind regarding the fit of a dog’s harness:

A proper harness should fit snugly around a dog’s chest.
It should allow the dog to breathe and move normally, and should not cut into the dog’s skin.
However, it should not be so loose that it will slip off if the dog pulls or twists around during walks.
A general rule of thumb is that you should comfortably be able to slide 1-2 fingers under a dog’s harness to ensure proper fit.

Before first use, owners should try slipping the harness over their dog’s head once it is in place on the chest; if the harness is loose enough to come off this way, it should be tightened.

Even if a harness is placed correctly, some escape artist pups will still figure out how to slip out. In this case, owners should not re-use the harness that their dog was able to escape, and should instead try a different type of harness that more effectively contains their pup.

This is a great video overview on fitting a harness to the five main types of dog harnesses:

What Is a Dog Harness?

A dog harness is a device that straps around the front half of a dog’s body and is attached to a leash to contain the dog during walks or training activities. The harness usually wraps around the front of the chest as well as around the back behind the front legs to hold the dog securely.

What Types of Dog Harnesses are Available?

Harnesses are usually made of fabric and have plastic or metal buckles and/or clips. Different fabrics may be used for different purposes.

Lightweight harnesses may utilize materials like mesh, and are intended for use with light activity or in warmer weather, or for smaller dogs that are easily weighed down.

Heavier-duty harnesses may be made of materials like nylon or polyester, and are intended for larger, stronger breeds or for use during more strenuous activity.

Many different harness designs also exist for different uses. Strap configuration or number may vary depending on the intended strength of the harness.

Some harnesses are secured with buckles, while some (usually for smaller dogs or dogs unlikely to pull at the leash) can be slipped on and off over the dog’s head.

Some harnesses are designed to tighten around the chest when a dog pulls on the leash in order to prevent this behavior; similarly, some harnesses have leash clips at the front of the chest to stop dogs from pulling.

Harnesses may have handles at the top to help lift dogs or prevent lunging behavior. Some harnesses may also feature storage pouches or pockets for the owner’s use.

What Are the Advantages of Using a Harness Over a Collar?

Unlike dog collars, most harnesses do not place pressure on a dog’s neck or windpipe (trachea) when a dog pulls at the leash.

Instead, the force of the pull is distributed to the front of the dog’s body.

This is much safer for short-nosed (brachycephalic) breeds like:

Pugs
English bulldogs
Shih tzus
French bulldogs

These breeds inherently have airway abnormalities that can prevent them from getting enough oxygen, which are made worse with added pressure from a collar.

Harnesses are also safer for dogs with medical conditions like collapsing trachea or spinal injuries, which can be exacerbated by the use of a collar.

What Are the Disadvantages of Using a Harness?

Compared to dog collars, harnesses are bulkier and their configuration may be more complicated to figure out. The many straps and buckles can be confusing for owners if they do not come with adequate instructions.

If not fitted correctly, dogs may be able to escape during walks.

Harnesses also take longer to put on before walks, which may be especially challenging with excitable dogs. Lastly, harnesses may allow dogs to pull at the leash with more force, especially if they are not designed to prevent pulling.

This is a good video overview of harnesses versus collars:

What Are Alternatives to Dog Harnesses?

As previously mentioned, dog collars are an alternative to harnesses, though they are not recommended for all dogs.

Head collars, or Gentle Leaders®, are another harness alternative.

These incorporate a nose loop that sits around the base of a dog’s muzzle, and a neck strap that secures behind the top of the dog’s head. A leash is attached under the dog’s chin. Head collars are designed to prevent pulling; when the dog pulls at the leash, the head collar puts gentle pressure around the muzzle to turn the head back toward the person holding the leash.

No pressure is applied to the airway with this device, and dogs can open their mouths normally while wearing it.

Additional Resources

For more on dog harnesses, check out our post on how to measure your dog for a harness, our post on the best escape proof dog harnesses, as well as:

And our individual harness reviews:

And our breed-specific harness guides:

Dr. Jennifer Masucci
Dr. Jennifer Masucci, VMD is a graduate of the University of Pennsylvania School of Veterinary Medicine. Through multiple years of working as a small animal general practitioner, Dr. Masucci is particularly well-versed in canine and feline medicine. Dr. Masucci is passionate about educating pet owners, so that they can offer the best care to their furry companions.