You bought a harness, put it on, and it immediately looks crooked. Too loose at the shoulders, too tight behind the front legs, or it constantly slides forward as soon as your dog starts walking. Sound familiar? For small dogs, the margin for a good fit is particularly small, and most size charts don't account for this sufficiently.
A poorly fitting harness is more than just an annoyance. It can restrict movement, irritate the skin, or even chafe for active dogs. And for small breeds like a Maltipoo, Bichon, or Cavapoo, their build is compact and sensitive: a narrow ribcage, soft skin, a short torso. This requires precision in measuring, not a guess based on weight.
Three measurements that really matter
Most brands ask for the chest circumference. This is the measurement you take just behind the front legs, at the widest point of the ribcage. Measure with a flexible tape measure, not too tight and not too loose. You want room for one to two fingers between the tape and your dog's skin. Write down this measurement, as this is your basic information.
The second measurement is the neck circumference, taken where a collar would sit. Not too high, not too low. Some harnesses have an adjustable neck opening, but it's still important to know if your dog is built narrow or wider here.
The third measurement, which few people take but makes a big difference, is the back length. Measure from the base of the neck, the point where the neck and back meet, to the base of the tail. For small dogs with a compact torso, this can be the deciding factor between a harness that stays in place nicely and one that constantly slides forward or backward.
How to measure this most easily?
Have your dog stand calmly on a flat surface, preferably not when they are excited. A small treat after measuring helps keep the mood good. Use a soft tailor's tape measure, or failing that, a piece of string that you then lay next to a ruler. Write down all three measurements before you start comparing.
Also, know that two dogs of the same breed and weight can look very different in terms of measurements. One Maltipoo has a broad ribcage and a short back, while another is narrow and elongated. Measurements always say more than weight.
What else to check on the size chart
Many brands provide a range: size S fits a chest circumference of 30 to 40 centimeters, for example. If your dog is exactly in the middle, choose that size without hesitation. If you're at the boundary, always choose the larger size and then adjust the harness. A harness that is just too small can never be adjusted properly. One that is slightly roomier can.
Also check how adjustable a harness is. Cheaper models often only have one adjustment ring, while a well-fitting harness for a small dog should be adjustable at at least two points: at the neck and at the chest. This allows you to fine-tune the fit to your dog's specific build.
After putting it on
A well-fitting harness moves with your dog, not for her. Your dog should be able to extend her front legs freely forward without the harness pulling up at the armpits. There should be no room to slip out, but also no pressure on the soft skin behind the front legs. The two-finger test also applies here: put two fingers under the harness on the chest and on the back. If that's comfortable, it fits well.
In the Holy Moly collection, you'll find harnesses for small dogs designed with precisely these things in mind.