The Life Stages of Dogs: From Puppies to Seniors

The stages of your dog’s life and what you need to know about their behavior.

Posted Nov 14, 2019

As your puppy grows into a dog and then begins to mature, both their needs and behavior change. There are four main stages in a dog’s life, according to the 2019 AAHA Canine Life Stage Guidelines.


The puppy stage is from birth until rapid growth stops. Depending on the breed and the size of dog, this is between 6 and 9 months. Small breeds stop growing at an earlier age than large breeds.

You will need to puppy-proof your home by keeping garbage locked up, electrical cords safe from chewing, and anything toxic (including medications and house plants) well out of reach. You may also wish to confine the puppy to certain parts of the house.

Sonja Kalee/Pixabay
A Toller puppy
Source: Sonja Kalee/Pixabay

Puppies have a sensitive period for socialization that begins before you bring your puppy home and continues until 12-14 weeks. Good breeders can make a big difference to the puppy’s future development by having a structured socialization plan. It’s important for you to continue this socialization by ensuring your puppy has a wide range of positive experiences.

Signing up for a good puppy class can help. Look for a class that is based on positive reinforcement, which includes handling exercises, carefully-supervised play, and exercises to prevent fear of loud noises (like fireworks) later on.

The American Veterinary Society of Animal Behavior says, “It should be the standard of care for puppies to receive such socialization before they are fully vaccinated.”

They say that puppies can start puppy class at 7-8 weeks, having had their first set of vaccinations a week beforehand, and their first deworming. This is in line with the 2015 AAHA Canine and Feline Behavior Management Guidelines which say, “The risks attendant with missing social exposure far exceed any disease risk.”

The new AAHA guidelines say that for small breeds, male dogs should be castrated at 6 months, and female dogs spayed before their first heat (5-6 months). For large breeds, spay/neuter surgery should be done once growth has stopped (9-15 months). Your veterinarian will help you decide what is best for your dog.

Young Adult

Young dogs go through a period in which they are still maturing, both physically and socially. This typically lasts until 3-4 years of age.

This is a time when people sometimes struggle with their dog’s behavior. You can build on what you and your dog learned from puppy class by signing up for adult dog obedience classes. If your dog has behavior issues, seek help sooner rather than later. Don’t assume that your dog will “grow out” of it.

This is also a good time to try out hobbies with your dog such as agility, nose work, or cani-cross (running with your dog). Some breeds need a lot of physical and cognitive enrichment. However, all dogs can benefit from enrichment, and small breeds often miss out, so remember to give little dogs plenty of enrichment and training opportunities too.

This is also a common time when people notice their dog has become afraid of fireworks. Seek help from a dog trainer as fear of fireworks (and other loud noises) can improve with training (Riemer et al 2019). You could also speak to your veterinarian to see if they think medication might help.

Mature Adult

The mature adult stage continues from maturity until 25% of the dog’s expected lifespan is left. For a dog with an expected lifespan of 12 years, this would take them up until they are 9.

By now you have probably settled into a routine with your dog and they are very well behaved, but don’t forget to keep rewarding the behaviors that you like to see.

For young and mature adult dogs, it’s important to know that behavior changes can be due to medical issues. A common one is if a house-trained dog suddenly starts to go to the bathroom in the house. Many people assume this is due to spite, but in fact, it’s a sign you need to see the veterinarian.

In addition to house-soiling, other behavioral signs in adulthood that mean you should make an appointment to see your vet include any new fears or reactivity; distress when left alone; fear and aggression; becoming a lot more (or less) active; and stereotypical behaviors such as overgrooming and turning in circles (Hammerle, 2015).

Among guide dogs, there’s some evidence of different developmental onsets for different behavior issues (Caron-Lormier et al 2016). A study of guide dogs who had to be retired early shows an early onset for fear and aggression and a later onset of issues around their willingness to work.

While we don’t know enough about the typical developmental onset of behavior issues, there is some evidence that new onset of fear of loud noises in mature dogs may be related to pain (Lopes Fagundes et al 2018).


The last quarter of a dog’s life, up until end-of-life, is considered the senior stage. Senior dogs can have impairments to vision and hearing, may be less mobile, and may have cognitive changes too.

Senior dogs may need you to make some adaptations to your home and lifestyle, such as a ramp or steps to help them get in the car, rubber mats to help with slippery floors, or a harness with a handle so you can support them while walking. If your dog has a vision impairment, keep your home tidy and don’t move furniture around to avoid them from bumping into things.

Senior dogs can still enjoy walks, even if they are slower than they used to be, and they still enjoy enrichment. Get creative if you need to, but make sure they are still part of family life.

At this stage, your vet may want to see your pet more often than before to help keep an eye on them. Taking good care of your senior dog can keep them happy in their golden years.


American Veterinary Society of Animal Behavior (2008) AVSAB position statement on puppy socialization.

Caron-Lormier, G., Harvey, N., England, G., & Asher, L. (2016). Using the incidence and impact of behavioural conditions in guide dogs to investigate patterns in undesirable behaviour in dogs Scientific Reports, 6 Article number: 23860 (2016)

Creevy, K. E., Grady, J., Little, S. E., Moore, G. E., Strickler, B. G., Thompson, S., & Webb, J. A. (2019). 2019 AAHA Canine Life Stage Guidelines. Journal of the American Animal Hospital Association, 55(6), 267-290.

Hammerle, M., Horst, C., Levine, E., Overall, K., Radosta, L., Rafter-Ritchie, M., & Yin, S. (2015). 2015 AAHA canine and feline behavior management guidelines. Journal of the American  Animal Hospital Association, 51(4), 205-221.

Lopes Fagundes, A. L., Hewison, L., McPeake, K. J., Zulch, H., & Mills, D. S. (2018). Noise sensitivities in dogs: an exploration of signs in dogs with and without musculoskeletal pain using qualitative content analysis. Frontiers in Veterinary Science, 5, 17.

Riemer S (2019) Not a one-way road—Severity, progression and prevention of firework fears in dogs. PLoS ONE 14(9): e0218150.