Dog harness (Y-Harness) - A little guide on measurement, biomechanics and build

[Tove09Tilda]

Hello everyone,

Some of you might already know that I am currently working on a Y-harness for my dog. During my research for this project, I noticed a recurring problem: many people try to build their own harnesses but miss several critical points. At the same time, there are surprisingly few good tutorials that explain not only how to build a harness, but also why certain design choices matter.

This guide is my attempt to change that. You are very welcome to contribute—whether by adding points I may have missed or by correcting information if something turns out to be inaccurate.

This guide is not intended for training purposes, provides no medical advice, and does not include product comparisons or commercial recommendations.

It is a design and fitting guide, grounded as much as possible in biomechanics. I am not a professional—just a science nerd who loves her dog and struggled to find properly fitting harnesses in stores. My goal is to share knowledge and reasoning, so you can make informed choices when designing or fitting a harness for your own dog.

In several parts, I will explain how to measure a dog for a harness and, more importantly, the reasoning behind those measurements and design decisions.

Before we dive into the topic : a few general words on harness building and materials. 

When building a harness, always ask about the intended use first, and only then look at the dog and honestly assess whether the harness type you have in mind is suitable. Some harness designs simply do not fit certain dogs—no matter how well they are made.

In my opinion, a harness must fit the dog first, and the purpose second.

When choosing fittings, always check:

• breaking strength

• maximum load

• overall size and weight

A practical rule I follow is:
maximum load = dog’s body weight × 4

Scale matters. A Dachshund needs very different (lighter) fittings than a Newfoundland. Oversized hardware adds unnecessary weight and can negatively affect balance and comfort.

Leather Choice (This Is Not Optional)

For leather harnesses, I recommend:

• 3–4 mm thickness

• normal to hard tempered leather (I personally prefer hard)

• leather from the butt or dorsal (spine) area

• preferably harness or bridle leather (For my own harness, I use Italian harness leather, double butt with a resin back. (Note: this particular leather is not suitable for equestrian saddlery work, but works well for dog harnesses.))

This type of leather stretches less over time and holds its shape better, which is essential if you want to use the harness for more than a few weeks.

Heavily oiled or fat leather is cheaper, yes—but it stretches significantly more and often has a very high breaking strength. In a worst-case scenario, we want the leather to fail before the metal fittings. If a dog gets caught and cannot slip out of the harness, it is safer for the leather to break than for rigid metal to hold indefinitely.

For animal welfare reasons: do not use heavily oiled or fat leather for harnesses.

Breed, Build, and Development

Breed and build must always be considered when fitting a harness.

For example:

• My current dog is long, mid-height, and slender

• My previous Springer Spaniel was long, sturdy, and rounder

• My mother’s dog is tall, long, slender, and overbuilt

Three dogs—three very different ideal harnesses.

Also consider how your dog may change with age. While growth and muscle development cannot be predicted perfectly, ignoring them entirely is a mistake. Some breeds are also more prone to injuries caused by ill-fitted harnesses, which makes proper fitting even more important. 

Part 1 – Biomechanics

As mentioned earlier: a harness has to fit the dog. The other way around is simply impossible.

The goal of a harness is to act as a leading device that interferes with the dog’s natural movement as little as possible. To achieve this, we must first understand canine biomechanics.

In this section, I reference several open-access scientific sources using APA 7 style, all linked at the end of this part. I will do the same in every following section whenever possible.

Harnesses and Their Effect on Movement

The way a harness distributes pressure across a dog’s body actively affects gait and overall movement.

Research on this topic is not entirely uniform:

• some studies show changes in spinal movement when a harness is used

• others show changes in stride length compared to walking on a collar

• some find little difference under certain conditions

What we can safely say is that harness design matters.

Many modern harnesses are marketed to restrict “undesirable” movement, such as pulling. This is not a long-term solution. If you are using a harness to prevent pulling, please work with a qualified trainer.

The main advantage of a harness is that it removes pressure from the neck and—ideally—distributes it more evenly across the body.

Stride Length, Shoulder Freedom, and Body Proportions

In a study by Williams et al. (2023), it was shown that the distance from a dog’s elbow to the ground is a key measurement when evaluating how restrictive a harness is on stride length.

This has practical consequences:

• Dogs with longer legs may benefit from a chest-strap harness rather than a Y-harness

• Smaller breeds often have relatively longer shoulders compared to forelimb length

• In these dogs, a chest strap may sit too high and actively restrict shoulder movement

The conclusion is simple but important:
no harness fits every dog.

Weight Distribution and the Kinetic Chain

A healthy dog carries up to 60% of its body weight on the forelimbs. The spine, shoulders, and limbs function as a single connected kinetic chain (Sürer et al., 2020). Even small changes in one area can alter overall movement patterns, affecting back motion and limb coordination.

Irregularities in movement are most easily detected at the trot.

An ill-fitted harness can, over time, lead to a shift of weight from the forelimbs to the hindquarters (Williams et al., 2023). One simple indicator for owners is to closely observe their dog’s movement on a collar versus in a harness.

Because dogs do not have a clavicle, the shoulder joint is a so-called “false joint,” stabilized primarily by muscle. Poor harness fit can affect both the scapula and the spinous processes of the spine.

Compensation and Injury Risk

Canine gait can be modeled in three dimensions and is normally symmetrical. This symmetry breaks down when the range of motion of any limb is restricted.

A study by Lin et al. (2020) demonstrates that dogs compensate rather than stop moving. Forward motion is maintained by redistributing forces—often until injury occurs.

Dogs are very good at hiding discomfort. This makes it our responsibility as owners and builders to ensure that equipment supports healthy movement instead of silently undermining it.

This concept is very similar to saddle fitting in horses.

A well-fitting saddle that allows the shoulder to glide freely results in smoother, more even movement. Girths and breastplates also offer useful parallels.

• The thoracic (belly) strap of a harness serves a similar function to a girth: keeping the equipment in place

• Like a girth, it must allow free elbow movement

• If it interferes with the elbow, stride length is restricted and weight shifts rearward

A breastplate in horses prevents forward saddle movement; in dog harnesses, the chest strap primarily distributes pressure and stabilizes the harness. Anything positioned in front of the shoulder has the potential to restrict stride extension and must therefore be fitted to the individual dog. This is a common shortcoming of chest-strap harnesses when strap width and placement are poorly chosen.

A Final Word on Restriction

For those who intentionally want to restrict their dog’s movement using a harness: be aware that restriction worsens under tension.

An open-access DAWGAIT dissertation shows that while a dog may appear to move normally at a walk, restrictions become evident at trot and gallop. What feels like “only a little restriction” can quickly turn into a real problem under load.

Personally, I use a harness to allow my dog to move freely in front of me. The leash is never tight—it is simply an extension of my arm, used for safety and communication. Our walks are calm, low-stress, and give my dog the freedom to explore while staying secure.

I also use harnesses as a secondary safety measure in new or potentially frightening situations, especially with young or insecure dogs.

Used thoughtfully and fitted correctly, a harness can be a valuable tool. Used carelessly, it can do long-term harm.

In the next part, I’ll show you exactly how I measured my dog for her new harness. I’m still waiting on some new tools, so updates might come a bit slower than I’d like—but I’ll share everything as soon as I can.

Sources: 

Lin, C.-C., Wu, C.-H., Chou, P.-Y., Chen, Y.-C., & Chen, C.-H. (2020). Evaluation of a multibody kinematics optimization method for three-dimensional canine pelvic limb gait analysis. BMC Veterinary Research, 16(1), Article 105.
https://doi.org/10.1186/s12917-020-02323-5

Sürer, E., Evangelisti, M. A., Paolini, G., Della Croce, U., & Manunta, M. L. (2020). A canine gait analysis protocol for back movement assessment in German Shepherd dogs. Veterinary Sciences, 7(4), Article 195.
https://doi.org/10.3390/vetsci7040195

Williams, E. R., Hunton, V. D., Boyd, J. A., & Carter, A. J. (2023). Effect of harness design on the biomechanics of domestic dogs (Canis lupus familiaris). PeerJ, 11, e14719.
https://doi.org/10.7717/peerj.14719

University of Georgia. (n.d.). DAWGAIT: Development and application of an open-source tool for canine gait analysis(Doctoral dissertation). UGA Open Scholar.
https://openscholar.uga.edu