Ever wonder what age your pup will stop growing? Here are a few crucial factors.

By Jennifer Nelson
July 06, 2021

If you're like most dog owners with a young dog or puppy, you may wonder when your dog will stop growing or how much he'll weigh when fully grown. When we rescued our Beagle-Hound mix, at age 10 months, it was estimated he would weigh about 35 pounds when he stopped growing. Fifty pounds and a year later, Phin was full grown. Good thing we weren't taking bets.

When Do Dogs Stop Growing?

"As a species, dogs have the most delightfully wide variation in size and appearance between breeds and even between individual puppies," says Dr. Rebecca Greenstein, veterinary medical advisor for Rover.

This makes it a tricky question to answer. Dr. Greenstein says, when an individual dog stops growing depends on things like the breed or breeds involved in his makeup and the overall size category of the dog. "As a general rule, smaller breeds reach maturity and adult size long before their giant breed counterparts.

"For instance, a teensy teacup Yorkie would be close to fully grown by well under a year, but a monstrous Newfoundland or Great Dane may not reach full size until 18 months or even two years of age," says Dr. Greenstein.

How Do Vets Determine How Much a Dog Will Weigh?

Despite what internet pop science suggests, there's really no one-size-fits-all calculation that help veterinarians determine when your dog will stop growing and how much she'll weight that applies to every dog breed.

At your first puppy veterinarian visit, your vet will get as much information as possible on your dog's breed or breeds, information about her puppy parents if known, and look at markers like the size of the pup's feet, bone structure, and overall size and weight as a starting point.

"With the explosion in popularity of designer hybrid breeds like Golden Doodles and Pom-Skis, there's even less utility in breed standards or growth charts since there's more cross-breeding and variation than ever," says Dr. Greenstein. "Bottom line: If anyone tries to tell you they can predict with 99% accuracy exactly how big a 'medium' Sheep-a-Doodle puppy will be, I'd run the other way."

What Affects your Dog's Growth and Weight?

Besides their breed and parents, a few things may affect your dog's growth including the age of their spay or neuter. Dr. Greenstein says the ideal age for fixing puppies has recently become a subject of increased interest and intense debate. In addition to its impact on growth, veterinary research is looking into whether the age of spay or neuter is linked to lifespan or the development of certain conditions.

"In Europe and in many shelter settings, desexing can often take place in puppies and kittens as young as three months, just to facilitate them getting adopted out and preventing unwanted pregnancies for the sake of population control," she says.

While your veterinarian is the best resource to discuss the age of spaying or neutering, Dr. Greenstein says she would be cautious of spaying or neutering before six months.

Another issue that can affect growth of course, is food. "How to properly nourish growing puppies isn't guesswork–there's a branch of veterinary medicine whose body of research tells us puppies (like babies) have unique and specific dietary needs and guidelines," says Dr. Greenstein.

That makes sense since puppies grow to adulthood much faster than us. Puppies require more protein, nutrients and different ratios of vitamins, minerals, and calories than adult dogs and nutrition is crucial to your puppy's proper growth.

As always if you have questions about spaying, neutering, or feeding, talk to your veterinarian. Meanwhile, watch your puppy grow. It goes fast.