My neighbor knocked on my door at 11 PM last Tuesday, slightly panicked. “Is Luna done growing? She’s 7 months and still looks like a potato with legs!”
I laughed because I’d asked the exact same question about my Chihuahua three years ago. We spend months watching our tiny puppies, wondering if they’ll stay pocket-sized or suddenly shoot up like a weed.
Here’s everything I wish I knew when I was obsessively measuring Milo’s paws every week.
The Short Answer (For People Who Hate Scrolling)
Most small breed dogs stop growing between 9-12 months old. Some toy breeds finish even earlier at 6-8 months, while others take the full year.
But here’s the thing – “stop growing” doesn’t happen overnight. It’s gradual, sometimes frustrating, and definitely not as predictable as those breed charts suggest.
What Is Considered a Small Breed Dog, Anyway?
Before we talk growth, let’s get on the same page about what “small” actually means.
The veterinary world classifies dogs by adult weight:
Toy Breeds: Under 10 pounds
Examples: Chihuahua, Yorkshire Terrier, Pomeranian, Toy Poodle
Small Breeds: 10-25 pounds
Examples: Shih Tzu, French Bulldog, Boston Terrier, Miniature Schnauzer
Medium Breeds: 25-50 pounds (for comparison)
When someone asks me “what is considered a small breed dog,” I usually say: If you can comfortably carry them for more than 5 minutes without your arms dying, they’re probably small breed.
Not scientific, but accurate.
The Growth Timeline: What to Actually Expect
Let me break this down month by month, based on what I’ve seen with literally hundreds of small breed puppies (perks of working with a vet).
Birth to 8 Weeks – The Rapid Fireball Phase
Your puppy doubles their birth weight in the first week. DOUBLES. Then they keep going.
During this phase, they’re with mom (or should be). If you’re getting a puppy younger than 8 weeks, that’s a red flag about the breeder.
8 Weeks to 4 Months – The Adorable Awkward Stage
This is when most people bring puppies home. They’re clumsy, their ears are too big for their heads, and they trip over their own feet.
Growth rate: About 5-10% of adult weight per week
Milo at 3 months looked like someone glued a Chihuahua head onto a sausage body. Completely disproportionate. Totally normal.
4 to 6 Months – The “Are You Sure They’re Not Broken?” Phase
Growth continues but starts slowing down. You’ll notice:
- Ears finally proportional to head
- Legs catching up to body length
- First signs of adult coat coming in
- Baby teeth falling out (fun times)
This is when people start asking “when do small breed dogs stop growing” because the rapid changes slow down and you think maybe they’re done.
They’re not. Not yet.
6 to 9 Months – The Almost-There Plateau
For toy breeds: This is usually when growth stops. A Yorkie at 8 months is pretty much adult-sized.
For small breeds: Still growing, but slowly. Maybe gaining a pound or two more, filling out in the chest and hindquarters.
My friend’s French Bulldog looked done at 7 months, then mysteriously got broader and more muscular over the next 3 months. Same height, just… beefier.
9 to 12 Months – The Final Stretch
Most small breeds hit their adult size now. They might fill out a bit more (muscle development, chest depth), but height-wise? Done.
Exception: Some breeds take until 15-18 months to fully mature mentally and physically. Beagles and Cocker Spaniels, I’m looking at you.
How to Tell If Your Dog Is Done Growing
Forget the calendar for a second. Here are the actual signs your pup has stopped growing:
1. Weight Plateau for 3-4 Weeks
Track their weight weekly. When it stops changing for a month, they’re probably done.
I kept a note in my phone: “Milo – Week 38: 6.2 lbs, Week 39: 6.2 lbs, Week 40: 6.3 lbs, Week 41: 6.2 lbs.” That’s when I knew.
2. Growth Plates Have Closed
Your vet can check this with X-rays if you’re really curious (or preparing for spay/neuter surgery). Growth plates are areas of developing cartilage at the end of long bones.
When they close? Growth stops. Usually happens by 10-12 months in small breeds.
3. Adult Teeth Are Fully In
By 6-7 months, all adult teeth should be present. This often correlates with slowing growth.
4. Energy Levels Shift
Puppies are insane energy tornadoes. Adult dogs? Still energetic, but with an off switch.
When Milo finally started napping for more than 20 minutes without waking up to destroy something, I knew we’d entered adult territory.
5. Sexual Maturity (For Unfixed Dogs)
Females have their first heat around 6-12 months. Males start marking and showing interest in female dogs around the same time.
This doesn’t mean growth is 100% done, but it’s a good indicator they’re close.
Breed-Specific Growth Timelines
Not all small breeds follow the same schedule. Here’s what I’ve observed:
Chihuahuas: 6-9 months, adult weight 4-6 pounds
(Milo was done at 8 months, 6.2 pounds)
Yorkshire Terriers: 9-12 months, adult weight 4-7 pounds
(My aunt’s Yorkie didn’t stop until 11 months, the little overachiever)
Pomeranians: 7-10 months, adult weight 4-8 pounds
Shih Tzus: 10-12 months, adult weight 9-16 pounds
(They bulk up late – all that fluff is deceiving)
French Bulldogs: 9-12 months, adult weight 16-28 pounds
(Males take longer and get stockier)
Dachshunds: 11-13 months, adult weight 16-32 pounds
(Those long spines take time to develop properly)
Boston Terriers: 12-14 months, adult weight 12-25 pounds
Miniature Schnauzers: 12 months, adult weight 11-20 pounds
For more details on specific breeds, check out our complete breed guides – I’ve covered over 30 small breeds in detail.
The Paw Size Myth (And Why It’s Nonsense)
“Look at those huge paws! He’s gonna be massive!”
I’ve heard this a thousand times. And yeah, sometimes big paws mean a bigger dog. But not always.
Some puppies just have goofy proportions. Milo’s paws looked enormous at 12 weeks. He’s 6 pounds as an adult. Those paws were a lie.
The only semi-reliable predictor? Parents’ size. If both parents are 8-pound Shih Tzus, your puppy probably won’t be 18 pounds. Genetics matter more than paws.
What Affects Growth Rate?
Several factors influence when small breed dogs stop growing:
Nutrition
Feed puppy food until they’re done growing. Premature switching to adult food can stunt development.
I wrote an entire guide on the best food for small breed puppies – proper nutrition literally shapes their adult size.
Spaying/Neutering Timing
This is controversial, so bear with me.
Early spaying/neutering (before 6 months) can slightly delay growth plate closure, leading to taller (but not heavier) dogs. The difference is minimal in small breeds – maybe half an inch.
I personally waited until Milo was 10 months for neutering, after discussing with our vet.
Health Issues
Parasites, chronic illness, or malnutrition during puppyhood can stunt growth permanently. This is why deworming and vet checkups matter so much.
Genetics
This is 80% of the equation. You can’t turn a Chihuahua into a Corgi through diet alone (though I’ve seen people try).
Growth Spurts vs. Gradual Growing
Here’s something weird: Some puppies grow steadily. Others have random spurts.
My sister’s Pomeranian stayed 5 pounds for six weeks, then suddenly shot up to 7 pounds in 10 days. Then plateaued again for two months.
During growth spurts, puppies:
- Sleep MORE (growth hormone releases during sleep)
- Eat more food
- Act clumsier (adjusting to new body dimensions)
- May have minor joint discomfort
If your puppy seems extra tired during a growth phase, that’s why. They’re literally building bones and muscles. It’s exhausting.
The “Filling Out” Phase (12-18 Months)
Even after height growth stops, small dogs spend 6 more months developing:
- Muscle definition
- Chest depth
- Coat fullness and texture
- Head shape (especially in breeds like French Bulldogs)
A 10-month-old Shih Tzu and an 18-month-old Shih Tzu of the same height can look completely different. The older one looks more “solid” and mature.
Common Worries (And When to Actually Worry)
“My Puppy Isn’t Growing!”
If your puppy hasn’t gained weight in 3+ weeks, talk to your vet. Could be:
- Parasites (super common)
- Food isn’t calorie-dense enough
- Underlying health issue
Use a dog food calculator to ensure proper portions.
“My Puppy Is Growing Too Fast!”
Rapid growth in large breeds causes joint problems. In small breeds? Less of an issue, but overfeeding is still bad.
Chubby puppies are cute but extra weight on developing joints = problems later.
“My Puppy Is Smaller/Larger Than Expected”
Breed standards are averages. Your Chihuahua might be 4 pounds or 8 pounds – both are normal if they’re healthy.
Milo is on the bigger end for Chihuahuas. Doesn’t make him less Chihuahua, just means he got different genetics from his parents.
The Runt Situation
Runts (smallest puppy in a litter) often catch up to littermates by 12 months. Not always, but usually.
I’ve met several “runt” stories where the tiny puppy ended up the biggest adult. Genetics are weird.
If you adopted a runt, give them extra nutrition and vet attention the first 6 months. They can absolutely thrive.
Exercise During Growth Phase: Don’t Overdo It
Here’s what vets don’t tell you loudly enough: Too much exercise during growth can damage developing joints.
Safe rule: 5 minutes of exercise per month of age, twice daily.
So a 4-month-old puppy gets 20-minute walks, twice a day. That’s it.
I know, I know – your puppy acts like they could run marathons. Their joints disagree. Trust me, I’ve seen the X-rays of dogs whose owners ran them too hard too young.
Short, frequent play sessions are better than one long exhausting adventure.
Travel Considerations for Growing Puppies
If you’re planning trips with your puppy, be mindful of their developing body. High-altitude destinations especially need consideration.
I learned this the hard way taking Milo to a mountain cabin at 5 months old. He got lethargic and refused to eat – scared me to death. Turns out puppies are more sensitive to altitude than adult dogs.
Read more about dogs and altitude sickness before planning that mountain getaway.
What to Do Once Growth Stops
When your dog hits adult size:
- Switch to adult food gradually (over 7-10 days)
- Adjust portion sizes – they need fewer calories now
- Update their ID tag with current weight (helpful for vets/emergencies)
- Consider spay/neuter if you haven’t already
- Switch from puppy to adult training focus
The Honest Truth About Size Predictions
Those online calculators that predict adult size? They’re educated guesses at best, complete nonsense at worst.
I plugged Milo’s info into three different calculators at 4 months old:
- Calculator 1: “Adult weight will be 8 pounds”
- Calculator 2: “Adult weight will be 5 pounds”
- Calculator 3: “Adult weight will be 11 pounds”
Actual adult weight? 6.2 pounds.
The only reliable predictors are parents’ size and watching your specific puppy’s growth curve. Everything else is just fun speculation.
Final Thoughts: Enjoy The Puppy Phase
I spent so much time worrying about Milo’s growth that I almost missed enjoying his puppy months.
Was he going to be too small? Too big? Why were his legs so short? Why did his ears stick up weird?
Looking back, I wish I’d relaxed more. He grew into exactly the dog he was meant to be – a healthy, if slightly neurotic, 6-pound Chihuahua who thinks he’s a Rottweiler.
Your small breed puppy will stop growing when they’re ready. Feed them quality food, give them proper vet care, and stop measuring them every three days (I see you).
They’re perfect at every stage.
Related Reading:
- What makes a small breed dog? – Complete breed database
- Best foods for growing puppies
- Low-shedding small breeds if you’re still choosing
Drop a comment telling me your puppy’s current age and weight – I love hearing growth stories! And if your puppy is currently in that awkward “all ears and paws” phase, snap a photo. You’ll laugh about it later.
