Best collar for fast-growing Bernese Mountain Dog puppy

A four-month-old Bernese Mountain Dog — you're right in the thick of that phase where you check the collar on Monday and it's almost too tight by Friday. Collar fit and safety matter more than most people think: too loose and it slips off, too tight causes real damage, and fast-growing giant breeds need a collar that keeps up with them week to week. To point you toward the right option — how much does your pup weigh now, roughly what neck size are you measuring, and is this primarily for ID tags and daily walks or will you be doing any lead training with it?

18kg at four months — he's going to be a big lad. At that growth rate you need a collar with a genuinely wide adjustment range, not just a couple of centimetres of play. What width collar have you been using so far, and has he shown any signs of discomfort or rubbing around the neck?

That off-centre buckle mark is worth taking seriously — it usually means the collar isn't sitting flat because the fit isn't quite right, and on a dog growing this fast that's easy to miss. For your boy I'd go with the Ruffwear Flat Out collar in the Large size. It adjusts from 51cm to 66cm, so it'll cover him from now well into adolescence, and the webbing is 25mm so it's a familiar width. What makes it worth the money over a basic nylon collar is the aluminium V-ring for tags that sits flat against the neck rather than flopping around, and the hardware is centred and low-profile so you won't get that off-centre pressure point again. It's also machine washable, which matters a lot with a muddy Bernese. You'll get maybe four to six months out of one collar rather than buying every few weeks.

Yes — the V-ring on the Flat Out is welded aluminium and sits snug against the collar, so the tag hangs below it without spinning or sliding to the side. It's more secure than the standard D-ring on most basic collars where the tag can work its way round to the back. Do get him microchipped as soon as you can though — it's the one form of ID that can't fall off or fade. In the meantime the tag on that collar will stay exactly where you put it.

Great choice. Measure his neck again when it arrives and aim for two fingers' width of slack — no more, no less. With a Berner you'll probably be moving the buckle every couple of weeks for the next few months, so check it as part of your routine. Enjoy this age — they're brilliant at four months, even if they eat collars faster than you can buy them.