Best harness for Papillon with deep chest

A Papillon with a deeper-than-usual chest is a genuinely tricky fit — most toy-breed harnesses are cut shallow and wide, which is fine for the typical Papillon build, but if your dog has more depth through the chest, you'll get that frustrating gaping at the sides no matter how much you tighten the straps. Small dog harnesses have specific fitting challenges at the best of times: most are too loose around the chest or too rigid for delicate builds, and what works for a Chihuahua is completely wrong for a Dachshund. So I'd love to get the details right for your dog — what's her weight, what are you using the harness for mainly (walks, travel, both?), and have you had any issues beyond the gaping, like rubbing under the armpits or the harness twisting during walks?

3.5kg with an unusually deep chest — that's exactly the combination that breaks standard sizing. Toy harnesses assume a shallow, narrow chest and a Papillon at that weight is already at the top of the range, so you end up between sizes on the depth axis even when the girth measurement looks right. The key thing you need is a harness with an independently adjustable chest strap, not just a single girth band, so you can actually bring the front plate flush against her sternum regardless of depth. Can I ask — does she pull at all on walks, or is she fairly relaxed on lead? That'll help me choose between two options I have in mind.

Perfect — that makes the choice straightforward. I'd go with the Rabbitgoo No-Pull Dog Harness in size XS. I know 'no-pull' sounds like overkill for a calm dog, but the reason I'm recommending it here is purely the construction: it has four adjustment points including a separate chest strap that lets you bring the front panel right down against the sternum, which is exactly what closes that gap you're getting. The soft mesh lies flat against the body rather than holding a rigid shape, so it actually contours to her deeper chest instead of bridging over it. The XS fits roughly 33–40cm girth, which should suit a 3.5kg Papillon well, and the front D-ring gives you a secondary clip point for extra security if you ever want it. It's widely available on Amazon UK and usually around £15–18. Given that she doesn't pull, you won't be using the no-pull feature, but the fit solution it provides is genuinely the best match for what you're describing.

It's fine for year-round use — Papillons are surprisingly resilient walkers and the harness itself sits on the chest and back rather than wrapping the whole body, so it's not like it's pulling warmth away. If she gets cold on winter walks, that's more about a dog coat than the harness. The mesh actually works in your favour because it won't stiffen in cold weather the way some neoprene or padded harnesses do, and it won't cause sweating in summer either. Just make sure you measure her girth before ordering rather than going purely by the weight guide — at 3.5kg she should be XS, but given her unusual proportions, a quick tape measure around the widest part of her chest will confirm it.

You're very welcome. Measure twice, order once — and if the XS girth is right but you still feel the chest strap needs a little more adjustment range, the Rabbitgoo does give you quite a lot of play on each point so you should be fine. Enjoy your walks with her — Papillons are wonderful little dogs on a lead once you've got the kit sorted.