How Do You Tell How Old a Dog Is? (Solved and Explained!)

Dog ages are measured in the same way that human ones are. You simply have to count the number of years that have passed from their birth, starting on a dog’s birthday.

Some pet owners will use what they refer to as dog years. While these are those that say that one human year equals seven dog years, the American Veterinary Medical Association actually considers the first year of most dog’s lives to be equivalent to around 15 human years.

Using this system, dogs would be 24 after their second human year and 28 after their third. Few people outside of the veterinary profession ever measure dog age in this way, however.

This is all well and good if you know exactly when a dog was born. Pet owners who don’t will have to rely on a few tricks to tell their dog’s age.

How Do You Tell How Old a Puppy Is?

Monitoring a puppy’s growth is probably the fastest way to get a decent guess as to how old they are. Most dog breeds experience a growth spurt between 8-16 weeks of age, and they’ll continue to grow over the next few months after that.

If your dog doesn’t seem to be growing visibly, then there’s a good chance they’re much more than 16 weeks old. On the other hand, a dog that’s growing very rapidly might be right around two months old.

Younger puppies tend to run around until they’ve completely tired themselves out as well. This behavior normally starts to vanish in older ones, though it depends somewhat on your dog’s personality.

How to Determine Dog Age By Teeth

Look in their mouth and see if the puppy has any teeth. Newborns don’t have any while 3-4 week old puppies usually just have fangs with no other teeth in their mouths.

At around 4-5 weeks of age, puppies start to grow regular-sized incisors. They’ll get premolars alongside their fangs at around 5-6 weeks of age, so you know a dog with a more complete set of teeth is at least that old.

While a puppy that’s eight weeks old is probably still considered a baby, he or she would have a full set of teeth at that point. At eight months, most domestic dog breeds will have their permanent teeth come in, though a full set doesn’t usually come in until a dog is a full year old.

Unfortunately, dogs that have dental problems might not be all that easy to age using this method, so don’t simply trust their teeth if they’re a rescue. Older puppies tend to test their boundaries might more than younger ones do, and you’ll want to pay attention to that as well as dentition when aging your dog.

Check Their Coat

Watch for any change in a puppy’s coat, which would indicate that your puppy is starting to approach the one year mark or so. As puppies age, they lose the soft down that they’re born with and start to grow a coarser coat that’s dense and thick.

Not all breeds grow the same exact type of fur as they get older, but pretty much all of them will get a denser coat as time goes on. If your puppy’s coat is still very shiny and fluffy, then there’s a good chance that he or she isn’t old enough for this to have happened yet.

Check Their Eyes

Any puppy that’s younger than around 14 days will avoid opening his or her eyes. Puppies usually open their eyes after around two weeks, and they’ll start to walk around this time.

Most puppies will still have some problems with their sight until a week has passed since they opened their eyes. If your puppy has fully opened eyes but still tends to wobble when trying to figure out his or her boundaries, then there’s a good chance that they’re just a little over three weeks old.

Any dog who is older than this and doesn’t have a vision issue should be able to see relatively well.

How’s Their Hearing?

According to the AKC, puppies are functionally deaf until they’re around three weeks old. They navigate totally by scent until they’re able to hear.

If your dog can’t hear anything, then there’s a good chance that they’re younger than three weeks. Pay close attention to their hearing ability.

Should you have a dog for more than three or four weeks and they still can’t hear, you’ll want to take them to the vet to see if something’s wrong.

How’s Their Build and Activity Level?

Adolescent dogs will still have a somewhat puppy-like activity level until they’re around two years old. Most dogs will reach their full size before this, however.

A majority of dog breeds reach physical maturity anywhere between 8-12 months. Females who aren’t spayed might start to experience their first heat cycles shortly before this.

Male puppies will start to have changes in their hindquarters after around seven weeks, which is when their testicles will normally start to descend.

Can a Dog DNA Test Tell Age?

Canine DNA tests can provide a good estimate for a dog’s age, but they’re not completely perfect. These tests are, however, the only relatively exact method available for determining the age of an adult dog.

By taking a sample of a dog’s genes, veterinarians are able to measure the telomeres that hold them together. Once they have length statistics for an individual dog, they’re matches with around 1,000 sample dogs that all have known exact ages.

This allows them to determine the age of a dog accurate to around several months. Each time a DNA strand replicates itself, it becomes ever so slightly shorter.

Compound structures at the end of each chromosome shorten over time, which is why veterinarians are able to use these statistics to provide an estimate based on the results of a DNA test.