Puppy development month by month
Most of the big changes land in the first year: baby teeth out by about 6 to 7 months, puberty from 6 to 9 months, adolescence around 8 months. Large and giant breeds keep growing well into the second year.
On this page
At a glance
| Stage | Key milestones | Meals a day | Vet visits |
|---|---|---|---|
| 8 weeks | All baby teeth in. Socialisation window open. Toilet and crate training start. | 4 | First check. Puppy vaccines from 6 weeks, every 3 to 4 weeks. Worming every 2 weeks. |
| 3 months | Baby teeth start to fall out at about 12 weeks. Socialisation period closing. | 4 until 12 weeks, then 3 | Next puppy vaccine. Worming moves to monthly. |
| 4 months | Adult teeth coming through. Energy needs drop from 3 to 2 times resting energy. | 3 | Final puppy vaccine at 16 weeks or later (WSAVA), finishing by 16 to 20 weeks (AAHA). |
| 5 months | Adult teeth still coming through. Some males already fertile. | 3 | Start the neutering conversation. |
| 6 months | Most adult teeth in. Small breeds close to adult size. Puberty from 6 to 9 months. | 3, then 2 from 6 months | Booster at about 6 months (WSAVA). Worming to the adult routine. |
| 7 to 9 months | Adolescence. All adult teeth by 7 months. Toy breed growth plates closing. | 2 | Checks move to every 6 to 12 months once rapid growth stops (AAHA). Neutering for small breeds if planned. |
| 10 to 12 months | Medium breeds reach adult size at about 12 months. Full bladder capacity at about 12 months. | 2, then 1 or 2 after 12 months | Large breed neutering window opens (AAHA: 9 to 15 months). |
| 12 to 18 months | Large breed growth plates close as late as 16 to 18 months. Giant breeds still growing. | 1 or 2 | Every 6 to 12 months (AAHA). |
| 18 months to 2 years | Giant breeds finish growing, some at 24 months. Social maturity from 12 to 36 months. | 1 or 2 | Every 6 to 12 months. Core boosters no more often than every 3 years (WSAVA). |
Puppy development by stage. Meals from the MSD Veterinary Manual feeding schedule; visit frequency from the 2019 AAHA canine life stage guidelines; vaccine timing from the WSAVA 2024 table. Your country's schedule may differ, see the vaccination schedule.
8 weeks
What is happening: the baby teeth are in. VCA says all deciduous teeth have erupted by about six weeks. The puppy is in the socialisation period, which the MSD Veterinary Manual gives as 19 days to 12 weeks, and they sleep most of the day: the AKC says 18 to 20 hours in one article and 16 to 18 hours in another, with naps of 30 minutes to two hours. The AKC also says 8 weeks is when bladder control is at its weakest. An AKC article by a certified trainer describes a first fear period at around 8 to 11 weeks, when a puppy can suddenly be spooked by things they ignored before.
- Meals: four a day from 6 to 12 weeks, on a puppy diet (MSD). The feeding calculator works out the amount.
- Vaccination: WSAVA says start no earlier than 6 weeks and repeat every 3 to 4 weeks until 16 weeks. If the breeder gave the first dose, ask for the date in writing. Your country's schedule is on the vaccination schedule page.
- Worming: every 2 weeks from 2 weeks of age until two weeks after weaning (ESCCAP UK), or at 2, 4, 6 and 8 weeks (CAPC, followed in the US and Canada). The deworming schedule has your country.
- Vet: the 2019 AAHA life stage guidelines suggest puppy visits every 3 to 4 weeks through the vaccine course.
- Training focus: toilet training, crate introduction, name and handling. AVSAB says puppy classes can start at 7 to 8 weeks, with at least one set of vaccines 7 days before the first class and a first deworming.
- Watch for: fear that does not settle with distance and food. AVSAB says owners of puppies showing fear should seek veterinary guidance.
3 months
What is happening: VCA says the baby teeth start to fall out at around 12 weeks as the adult teeth begin to erupt. MSD ends the socialisation period at 12 weeks and says failing to expose puppies to social and environmental stimuli at 3 to 12 weeks raises the risk of fearful behaviour as adults. AVSAB calls the first three months the most important socialisation period and says to keep going after it.
- Meals: drop from four to three at around 12 weeks. MSD gives three a day from 3 to 6 months.
- Vaccination: the next dose, 3 to 4 weeks after the last under WSAVA.
- Worming: ESCCAP UK moves to monthly until 6 months. CAPC moves puppies onto a monthly preventive that covers roundworm.
- Training focus: keep socialising on the socialisation checklist, practise short spells alone, and use the toilet routine. VCA's rule of thumb is about 3 hours of bladder control at 3 months.
- Watch for: chewing everything, which the teething timeline explains, and any retained baby tooth later on.
4 months
What is happening: MSD says permanent teeth usually begin to appear at around 4 to 5 months, so this is peak chewing. The MSD energy table drops a puppy from 3 times their resting energy requirement to 2 times after 4 months, which the feeding calculator does for you. VCA says a puppy of around 4 months should be learning to ask to go outside.
- Meals: three a day (MSD).
- Vaccination: WSAVA puts the last puppy dose at 16 weeks or older, and up to 20 weeks in especially high risk situations. The 2019 AAHA guidelines finish puppy vaccines at 16 to 20 weeks. Some countries' usual schedules differ, which the vaccination schedule shows.
- Worming: monthly (ESCCAP UK) or the monthly preventive (CAPC).
- Training focus: recall, loose lead walking and settling on a mat, all reward based.
- Watch for: diet creep. MSD's energy factor falls at 4 months, so food per kilogram of body weight falls too.
5 months
What is happening: adult teeth are still coming through, which MSD says starts at around 4 to 5 months. The AKC says males can be capable of reproducing as early as 5 months, and the 2019 AAHA guidelines say first heat can come as early as 4 months in some small breeds.
- Meals: three a day.
- Vaccination and worming: finish any outstanding puppy doses. Monthly worming continues to 6 months (ESCCAP UK).
- Neutering: start the conversation with your vet now, because AAHA's window for spaying small breed females is before the first heat, at 5 to 6 months. See the neutering section below for the other published positions.
- Training focus: keep up handling and short training sessions. Growing independence is normal.
- Watch for: a baby tooth still in place beside the adult one. VCA says the canines are the usual site, especially in small and short nosed breeds, and that retained baby teeth need to be removed. The teething timeline has the detail.
6 months
What is happening: VCA says all adult teeth have normally erupted by six months, and MSD says all are present by 7 months. On the AKC growth chart a small breed is about 75 percent of adult weight at 6 months, a medium 66 percent, a large 60 percent and an extra large 50 percent, and the AKC says small breeds typically stop growing at 6 to 8 months. MSD says adolescence begins with sexual maturity at 6 to 9 months, later for giant breeds. The AKC says a female's first heat often comes between 6 and 15 months. VCA says most puppies are fully toilet trained by 6 months.
- Meals: two a day from 6 months (MSD).
- Vaccination: WSAVA advises a booster at about 6 months rather than waiting until 12 to 16 months, to catch puppies that did not respond earlier. Not every country's usual schedule does this, so check the vaccination schedule.
- Worming: ESCCAP UK moves to at least every three months from 6 months. CAPC keeps dogs on year round monthly parasite control.
- Neutering: AAHA suggests castrating small breeds at 6 months. Other bodies advise waiting longer. See below.
- Training focus: the AKC's trainer article places a second fear period somewhere between 6 and 14 months, earlier in small breeds. Do not force a frightened dog towards the thing they fear.
- Watch for: signs of a first heat. The AKC lists a swollen vulva, extra licking, weeing more often and a red discharge for 7 to 10 days. A female can get pregnant on her first heat.
7 to 9 months
What is happening: this is adolescence. In a study of potential guide dogs published in Biology Letters in 2020, carers rated dogs as less trainable at 8 months than at 5 or 12 months, the dogs were more likely to ignore 'sit' from their carer, and separation related behaviour scored 36 percent higher at 8 months. It passed by 12 months. The AKC's chief veterinarian says the long bone growth plates of toy dogs fuse at around 6 to 9 months, and the AKC says many dogs are 9 to 11 months old before their growth plates close.
- Meals: two a day (MSD). Large and giant breeds stay on a large breed puppy food. The AKC says these are lower in calcium and less energy dense.
- Vet: AAHA ends the puppy life stage when rapid growth stops, at about 6 to 9 months depending on breed and size, and moves to checks every 6 to 12 months.
- Neutering: the AKC's chief veterinarian says 6 to 9 months may suit toy and small breeds. Talk to your vet.
- Training focus: go back to basics with high value rewards, keep sessions short and do not read the dip as defiance.
- Exercise: RSPCA Australia says over exercising puppies can affect bone and muscle development, especially in large and giant breeds. Keep to self paced play rather than long runs.
- Watch for: any gaps in the adult teeth after 7 to 8 months, and new fears or separation problems. Get help early.
10 to 12 months
What is happening: the AKC says medium breeds reach adult size at around 12 months, while on its chart a large breed is about 85 percent and an extra large breed about 80 percent grown at 12 months. RSPCA UK says dogs do not have full bladder capacity until about 12 months. In the 2020 adolescence study, trainability had recovered by 12 months.
- Meals: two a day until 12 months, then one or two on an adult diet (MSD). RSPCA Australia advises feeding adult dogs at least twice a day to help avoid bloat.
- Food switch: the AKC says puppy formulas are typically fed until around 11 to 14 months. Ask your vet when to switch a large or giant breed.
- Vaccination: some countries give the first adult booster at 12 months. The vaccination schedule shows yours.
- Neutering: AAHA says large breed males should be castrated when growth is complete, usually 9 to 15 months.
- Training focus: proofing recall and manners in busier places.
- Watch for: weight. A dog that is still eating puppy portions after growth slows will gain fat quickly.
12 to 18 months
What is happening: the AKC's chief veterinarian says the growth plates of large and giant breeds fuse later, as late as 16 to 18 months. The BVA puts skeletal maturity at 12 to 23 months depending on breed, larger breeds later. The AKC says giant breed puppies grow until 12 to 18 months, and that large and giant breeds may not mature sexually until 16 to 18 months. VCA says excessive chewing tends to settle around 18 months.
- Meals: one or two a day on an adult diet (MSD).
- Vet: the 2019 AAHA guidelines suggest a check every 6 to 12 months for a young adult.
- Neutering: the large breed window. AAHA says 9 to 15 months for large breed males and 5 to 15 months for large breed females, the AKC's chief veterinarian says near or over 12 to 18 months, and the BVA says after skeletal maturity.
- Exercise: the AKC says never do road work or jogging with a dog under 14 to 18 months, especially large and giant breeds, until the growth plates have fused. Ask your vet before sports with a lot of running and jumping.
- Watch for: weight gain after neutering. AAHA says the risk of obesity in neutered dogs was greatest in the 2 years after surgery.
18 months to 2 years
What is happening: the AKC says very large breeds such as Mastiffs may not reach full size until 24 months, and RSPCA Australia says some large and giant breeds keep growing until about 18 to 24 months. MSD says social maturity, when behaviour with other dogs and people becomes more stable and predictable, arrives between 12 and 36 months. AAHA says physical and social maturity is complete in most dogs by 3 to 4 years.
- Meals: one or two a day on an adult diet (MSD).
- Vaccination: WSAVA says core vaccines should then be given no more often than every 3 years. Non core vaccines such as leptospirosis are usually yearly. The vaccination schedule has your country's routine.
- Worming: at least every three months (ESCCAP UK) or year round monthly control (CAPC). The deworming schedule has your country.
- Vet: every 6 to 12 months (AAHA).
- Training focus: this is when harder exercise and dog sports can start, after a vet check for large and giant breeds.
When to neuter: the published positions
Published ages run from 5 or 6 months to 23 months, and the split tracks size: the bigger the dog, the more of these bodies advise waiting until growth has finished. The trade off AAHA describes is fewer mammary tumours and unwanted litters when done early, against lower risk of some orthopaedic problems, some cancers and urinary incontinence when done later. This is a conversation to have with your vet, and Puplr does not pick a side.
In Australia, RSPCA Australia notes that some states, territories and local councils require dogs to be desexed by a certain age, and the age varies by area.
| Source | Position |
|---|---|
| AAHA, 2019 canine life stage guidelines (US) | Expected adult weight under about 20 kg (45 lb): castrate at 6 months, spay before the first heat at 5 to 6 months. Over about 20 kg (45 lb): castrate when growth stops, usually 9 to 15 months, spay at 5 to 15 months using clinical judgement. |
| American Kennel Club, chief veterinarian | 6 to 9 months may suit toy and small breeds. Large or giant breeds may need to wait until near or over 12 to 18 months. Decide case by case with your vet, which is also the AVMA's position as the AKC quotes it. |
| BVA with BSAVA (UK) | Neuter after skeletal maturity, generally 12 to 23 months, larger breeds later. Neuter most females; males case by case. Neutering before 6 months is linked to more orthopaedic problems and possibly urinary incontinence in females. |
| PDSA (UK) | Most dogs around 6 months, from 4 to 6 months, and a large or giant breed may be advised to wait. After a season, spay 2 to 3 months later. |
| RSPCA Australia | Sterilise as early as possible under veterinary supervision, with the right age depending on the individual animal. |
Published neutering timing by source
This is general guidance, your vet sets the actual schedule. Local disease risk, the products your clinic stocks and your puppy’s own history all change the plan. Take this page to your vet as a starting point, not as an instruction.
Buying guides for this
Common questions
When do puppies stop growing?
It depends on size. The AKC says small breeds typically stop at 6 to 8 months, medium breeds at around 12 months, and giant breeds at 12 to 18 months, with very large breeds such as Mastiffs sometimes not full size until 24 months. The adult size predictor estimates it for your puppy.
When do puppies hit puberty?
MSD says sexual maturity, and with it adolescence, starts at 6 to 9 months, later for giant breeds. The AKC says a female's first heat often comes between 6 and 15 months, and males can be fertile from 5 months.
Do puppies go through a teenage phase?
Yes. A 2020 study of potential guide dogs found they were less responsive to their carers at 8 months than at 5 or 12 months, with more separation related behaviour. It passed. Stick with reward based training and short sessions through it.
When should I neuter my puppy?
Published advice ranges from about 5 to 6 months to 23 months and depends heavily on size. AAHA says 6 months for small breeds and after growth stops for large ones, the BVA says after skeletal maturity at 12 to 23 months, and PDSA says around 6 months for most dogs. Decide with your vet.
How many meals a day does a puppy need by age?
Four a day from 6 to 12 weeks, three from 3 to 6 months, two from 6 to 12 months, then one or two on an adult diet, according to the MSD Veterinary Manual feeding schedule.
When do growth plates close in dogs?
The AKC's chief veterinarian says around 6 to 9 months in toy dogs and as late as 16 to 18 months in large and giant breeds. The BVA puts skeletal maturity at 12 to 23 months depending on breed. That is why the AKC advises against jogging before 14 to 18 months.
How much should a puppy sleep?
A lot. The AKC says young puppies sleep 18 to 20 hours a day in one article and 16 to 18 hours in another, often napping for 30 minutes to two hours after play. Give the puppy a quiet place to nap and do not wake them for company.
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How we worked this out
Stage by stage facts are pulled from the sources below rather than from a single published month by month plan, because no veterinary body publishes one. The meal counts, the vaccination and worming milestones and the teething ages are kept consistent with the Puplr feeding calculator, vaccination schedule, deworming schedule and teething timeline, which carry the full detail and the country differences.
Neutering is the biggest disagreement. AAHA splits by a projected adult weight of 45 lb (about 20 kg), the BVA says wait for skeletal maturity at 12 to 23 months for every dog, PDSA says around 6 months for most dogs, RSPCA Australia says as early as possible under veterinary supervision, and the AKC's chief veterinarian says 6 to 9 months for small breeds and up to 12 to 18 months for large ones. All five are shown and none is recommended over the others.
Growth plate closure has no single vet table. The AKC's chief veterinarian gives 6 to 9 months for toy dogs and as late as 16 to 18 months for large and giant breeds, another AKC article says many dogs are 9 to 11 months, and the BVA gives skeletal maturity as 12 to 23 months. The ranges overlap and are shown as ranges.
Puberty: MSD gives 6 to 9 months, later for giant breeds. The AKC gives first heat at 6 to 15 months, and AAHA says first heat ranges from 4 months in some small breeds to 24 months in some large ones.
Fear periods (8 to 11 weeks and 6 to 14 months) come from an AKC article by a certified dog trainer. No veterinary body reached in this pass, including AVSAB and MSD, publishes fear period ages, so they are attributed to the AKC and not stated as settled fact.
Adolescence ages come from one study of potential guide dogs (Asher and colleagues, Biology Letters, 2020) and from MSD's start of adolescence at sexual maturity. Pet dogs of other breeds may differ.
Sleep: the AKC publishes both 18 to 20 hours and 16 to 18 hours a day for young puppies in two different articles. Both are shown.
The five minutes of exercise per month of age rule is traceable to the Royal Kennel Club, which gives five minutes of formal exercise per month of age, up to twice a day, as a rule of thumb. PDSA, a veterinary charity, says there is no scientific evidence behind it and it is not appropriate for most puppies, so it is not used as a target here. What is sourced is RSPCA Australia's warning against over exercising growing puppies, the AKC's advice against road work and jogging before 14 to 18 months, and a 2012 Norwegian study (Krontveit and others) that linked stairs before 3 months to hip dysplasia and off lead exercise on soft ground to a lower risk.
Sources
- MSD Veterinary Manual, social behavior of dogs: https://www.msdvetmanual.com/behavior/normal-social-behavior-and-behavioral-problems-of-domestic-animals/social-behavior-of-dogs
- MSD Veterinary Manual, feeding schedule for puppies: https://www.msdvetmanual.com/multimedia/table/feeding-schedule-for-puppies
- MSD Veterinary Manual, daily maintenance energy requirements for dogs and cats: https://www.msdvetmanual.com/multimedia/table/daily-maintenance-energy-requirements-for-dogs-and-cats
- MSD Veterinary Manual, dental development of dogs: https://www.msdvetmanual.com/dog-owners/digestive-disorders-of-dogs/dental-development-of-dogs
- VCA Animal Hospitals, teeth, teething and chewing in puppies: https://vcahospitals.com/know-your-pet/teeth-teething-and-chewing-in-puppies
- VCA Animal Hospitals, how to potty train your puppy: https://vcahospitals.com/pediatric/puppy/behavior-training/how-to-potty-train-your-puppy
- 2019 AAHA Canine Life Stage Guidelines: https://www.aaha.org/wp-content/uploads/globalassets/02-guidelines/canine-life-stage-2019/2019-aaha-canine-life-stage-guidelines-final.pdf
- AAHA, when should I spay or neuter my pet: https://www.aaha.org/resources/spay-or-neuter/
- WSAVA 2024 core and non core vaccines for pet dogs, table: https://wsava.org/wp-content/uploads/2025/06/Dogs-Vaccination-Table.pdf
- ESCCAP UK and Ireland, deworming frequency advice: https://www.esccapuk.org.uk/uploads/docs/q8e61ahf_003_Deworming_frequency_advice.pdf
- Companion Animal Parasite Council, ascarid (roundworm) guideline: https://capcvet.org/guidelines/ascarid/
- AVSAB Position Statement on Puppy Socialization: https://avsab.org/wp-content/uploads/2018/03/Puppy_Socialization_Position_Statement_Download_-_10-3-14.pdf
- British Veterinary Association, neutering of cats and dogs policy: https://www.bva.co.uk/take-action/our-policies/neutering-of-cats-and-dogs/
- PDSA, dog neutering: a guide to castration and spaying: https://www.pdsa.org.uk/pet-help-and-advice/pet-health-hub/other-veterinary-advice/dog-neutering-a-guide-to-castration-and-spaying
- RSPCA Australia Knowledgebase, should I have my pet desexed: https://kb.rspca.org.au/categories/companion-animals/desexing/should-i-have-my-pet-desexed
- RSPCA Australia Knowledgebase, how should I exercise my puppy: https://kb.rspca.org.au/categories/companion-animals/dogs/puppies/how-should-i-exercise-my-puppy
- RSPCA Australia Knowledgebase, what should I feed my puppy: https://kb.rspca.org.au/categories/companion-animals/dogs/puppies/what-should-i-feed-my-puppy
- RSPCA UK, how to toilet train your puppy or dog, on bladder capacity: https://www.rspca.org.uk/adviceandwelfare/pets/dogs/training/toilettraining
- American Kennel Club, when do dogs stop growing: https://www.akc.org/expert-advice/health/when-does-my-puppy-finish-growing/
- American Kennel Club, how to care for your large breed dog: https://www.akc.org/expert-advice/puppy-information/how-to-care-for-your-large-breed-dog/
- American Kennel Club, sexual maturity in puppies: https://www.akc.org/expert-advice/health/sexual-maturity-in-puppies-what-to-expect/
- American Kennel Club, what is the best age to neuter or spay your dog: https://www.akc.org/expert-advice/vets-corner/neutering-spaying-right-age-dog/
- American Kennel Club, puppy fear periods: https://www.akc.org/expert-advice/training/puppy-fear-periods/
- American Kennel Club, how much do puppies sleep: https://www.akc.org/expert-advice/health/how-much-do-puppies-sleep/
- American Kennel Club, setting schedules and developing a routine for your new puppy: https://www.akc.org/expert-advice/training/setting-schedules-and-developing-a-routine-for-your-new-puppy/
- Asher and colleagues, Teenage dogs? Evidence for adolescent phase conflict behaviour, Biology Letters, 2020: https://doi.org/10.1098/rsbl.2020.0097
- Royal Kennel Club, puppy and dog walking tips (the five minutes per month rule): https://www.royalkennelclub.com/your-dog/dog-training/get-started/dog-training-and-games/puppy-and-dog-walking-tips/
- PDSA, exercising your puppy: https://www.pdsa.org.uk/pet-help-and-advice/looking-after-your-pet/puppies-dogs/exercising-your-puppy
- Krontveit and others, housing and exercise related risk factors for hip dysplasia, American Journal of Veterinary Research, 2012: https://doi.org/10.2460/ajvr.73.6.838
Last reviewed 2026-09-25.