Puppy’s First Dog Door: Sizing for the Dog Yours Will Become

A puppy doubles, triples and quadruples in size in its first year, which makes puppyhood the easiest time to buy the wrong dog door. A flap chosen for the puppy standing in front of you today can be outgrown before the dog’s first birthday — and a door the dog has to duck and squeeze through is a door it learns to dislike. Our advice when choosing a dog door for a puppy is simple: size for the adult dog yours will become, and introduce that properly sized door while the puppy is young, confident and learning everything at speed. A dog door for puppies is, in other words, a dog door for the adult they turn into.

Sizing a dog door for puppies: the three sizes by adult breed

We fit three sizes across the UAE. Medium is a 23×35 cm opening, suiting adult Bulldogs, Shih Tzus and Poodles. Large is 28×45 cm, for adult Beagles and Pointers. X-Large is 36×65 cm, for adult Labradors, Golden Retrievers, Huskies and Great Danes.

For a puppy, read the chart by the breed’s adult size, not the puppy’s current measurements. A ten-week-old Labrador puppy would fit through a Medium flap today and be defeated by it within months; its door is the XL its adult self needs. A Shih Tzu puppy, by contrast, is growing towards the Medium it will use for life. If your puppy is a crossbreed or a rescue of uncertain mix, work from the best estimate of adult size — your vet’s growth assessment, or the size of the parents if they are known — and if the estimate straddles two sizes, choose the larger. A door slightly generous for the adult dog costs nothing; a door slightly tight costs confidence every single day.

Where a puppy’s adult size is genuinely unpredictable, there is an honest alternative: wait. A door fitted at eight or nine months, when growth has slowed and the adult frame is mostly visible, removes the guesswork — and puppies manage perfectly well with supervised garden access in the meantime.

Why a big door does not overwhelm a small puppy

Owners worry a puppy will be frightened or physically unable to use an adult-sized flap. Size itself is rarely the problem — flap weight is the thing to manage. During the first introductions, the flap is held or propped fully open so the puppy simply walks through a doorway and learns the route. As confidence grows, the flap is lowered in stages: resting lightly against the puppy so it feels the touch, then closing halfway, then fully, until the puppy pushes it with its chest as a matter of routine. A puppy that learns on a staged flap grows up treating the full-size door as the most natural thing in the house.

The step-over matters too. The rise — the height of the bottom of the opening above the floor — is set when the door is fitted. For a household whose dog is a puppy now, we set the rise for the adult dog’s leg length, but it is worth telling us a puppy will use the door in the meantime: a low adult rise suits large breeds’ puppies well, and for small breeds the adult rise is naturally low.

Introducing the door: a gentle first week

• Start with the garden side. Puppies are motivated to get out to the interesting smells and back in to you. Practise in both directions, with a person and a reward waiting on each side.
• Keep sessions short and successful. Three or four passes, then stop while it is going well. Puppies learn routines fast but tire and get silly faster.
• Never push a puppy through. A puppy posted through a flap learns the door is something done to it. Lure, wait, reward — the puppy must choose the pass itself for the lesson to stick.
• Supervise early outdoor access. Until recall and house training are established, a dog door is for supervised freedom, not unsupervised roaming — and if you need the door closed, the locking panel slides in and the route is shut.

For dogs we fit Hakuna Pets and PetSafe doors, whose magnetic seals pull the flap shut behind the dog — worth having in a puppy household, because a puppy will not check whether the flap closed against the heat and dust behind it.

Where the puppy’s door goes

The fitting itself is the same as any adult dog’s. In glass, the flap sits in a made-to-measure replacement panel; your original glass is stored and swapped back in 30 minutes when you move out, so the installation is 100% rental-friendly with no landlord NOC. For sliding doors, a track insert in the standard white aluminium frame with clear glass can be fitted the same day if booked before 10 AM, and custom RAL powder-coated frames take 2–3 days. The only difference a puppy makes is the conversation beforehand: tell us the breed, the age and the expected adult size, and the door is specified for the dog at two years old, not two months.

Frequently asked questions

At what age can a puppy start using a dog door?

Once a puppy is steady on its feet, confident moving around the home and having supervised garden time, it can start learning the door with the flap held open. There is no fixed week count — readiness is about confidence and coordination, and your vet can confirm your puppy is ready for independent garden access.

Should I buy a small door now and a bigger one later?

Almost never. Two doors mean two panels and two fittings, and the first door’s hole rarely matches the second’s. Sizing for the adult dog from the start, with staged training while the puppy is small, gives one door for the dog’s whole life.

My puppy is a crossbreed. How do I estimate adult size?

Use every clue available: the parents’ sizes if known, your vet’s growth assessment, and the breed mix’s typical adult range. If the estimate lands between two of our sizes — Medium 23×35 cm, Large 28×45 cm, X-Large 36×65 cm — choose the larger size.

Will an adult-sized flap be too heavy for my puppy?

Not during training, because the puppy does not push the full flap until it is ready. The flap is held open, then lowered in stages, so the weight is introduced gradually as the puppy grows into both the technique and the strength.

Can I fit the door now if my puppy has not finished growing?

Yes — that is exactly the point of growth-aware sizing. Tell us the breed and your vet’s expected adult size, and the door is made for that adult dog. The puppy learns on it now with the flap staged open, and never outgrows it.

Fit one door for the dog’s whole life

WhatsApp us on +971 52 443 2655 with your puppy’s breed, age and expected adult size, plus a photo of the door or glass panel, and we will confirm the right size of dog door for puppies before anything is made. You can also email admin@petdoorfix.com. We fit dog doors across all seven UAE emirates.

Next guide: Dog Doors for Senior and Arthritic Dogs: Low Thresholds and Easy Flaps