Pick a muzzle he can live in
Training starts with the right equipment: a basket-style muzzle with room for a full pant, an open mouth, and drinking. A dog who cannot pant cannot cool himself or settle, so fabric sleeves that clamp the mouth shut are only ever for a few vet-handled minutes, never for walks or training sessions. The basket should sit clear of his eyes, not press on the end of his nose, and stay put when he shakes his head. Bring treats to the fitting — the muzzle's very first appearance in his life should already predict food.
Stage one: the muzzle is a treat machine
For the first sessions, do not put it on him at all. Show him the muzzle, feed a treat, put it away. Repeat until his response to seeing it is to look at you expectantly. Then rest it on the floor with treats inside the basket so he dips his own nose in to fish them out, and smear something lickable inside to lengthen each dip. Nothing is fastened, nothing is chased — he controls every approach, and he can walk away whenever he likes. A dog who chooses to push his nose in is learning the opposite of stress.
Stage two: duration before straps
Once he dives in happily, start paying for time: nose in for one second, treat through the basket; then three seconds, then five, feeding steadily while his face is inside. Let him pull out whenever he wants at first, then gradually ask for a moment longer before the treat lands. Only when he will hold his nose in calmly for ten seconds or so do you touch the strap — rest it over his head without fastening, treat, remove. Fasten it for a few seconds in the next session, then minutes, always with the treats flowing early on.
Stage three: wear it doing things he loves
A muzzle that only appears at the vet will always smell of trouble. Once it fastens comfortably, put it on for the good parts of life: the start of a favourite walk, a sniffy game in the garden, dinner scattered in the grass. Keep the first outings short, watch for pawing, rubbing his face on the ground, or shutting down and standing still — those say the session ran long or a step was skipped, so end on a treat, remove it calmly, and drop back a stage next time. Never use the training muzzle as a punishment or leave it on an unsupervised dog.
Recheck the fit as he grows and settles
A muzzle fitted to a young dog may rub six months later, and a dog who gains or loses condition can end up with a basket that slides toward his eyes. Recheck the fit monthly while he is still growing: two fingers of clearance, straps snug without digging, and room for that full pant on a warm day. A dog who starts pawing at a muzzle he previously ignored is usually reporting a fit problem, not forgetting his training — solve the rubbing first and the pawing generally stops with it.
Keep the stages straight between trainers
Muzzle conditioning unravels when one person is at the nose-dip stage and another straps it on for a full walk because he seemed fine. Note which stage he has genuinely reached and what the next step is, and let everyone work from that. KinsLe's Care Teams holds the muzzle-training stages as assigned duties on his profile, each marked complete as he passes it, so his progress survives a change of handler.