Ask a Vet: How Can You Tell How Old a Dog or Puppy Is?

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Ask a Vet: How Can You Tell How Old a Dog or Puppy Is?

Dogs age at different rates based on lifestyle and genetics, but there are still ways to determine age.

Dr. Eric Barchas  |  Oct 8th 2013  |   1 Contribution

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If you purchased your dog from a breeder or acquired your dog from a litter with a known birth date, then you know your dog's age precisely. However, plenty of dogs out there were acquired from shelters or found as strays. The age reported to you by the shelter may be inaccurate -- sometimes, it seems, inexperienced volunteers are assigned the task of estimating ages of dogs and puppies when they arrive. Is it possible to look at a puppy or dog and guess how old it is?

"Eyelids.getting.heavy." Sleepy Puppy by Shutterstock

The answer is yes -- within reason. This article will go through the stages of canine development and aging so that you will have some idea of how to estimate a dog's age. But don't forget that dogs, like humans, age at different rates. Some age well, and others don't. The difference is based upon genetics and lifestyle. There can be very marked differences in aging between breeds -- a Great Dane is elderly at seven years old, whereas a seven-year-old Chihuahua is barely middle aged.

Tips for estimating the age of a puppy or dog

Birth to 2 weeks of age: Newborn puppies are born toothless and with their eyes closed. These features can be used to identify puppies that are less than two weeks of age. Puppies this age spend most of their time rooting, suckling, and sleeping.

This one is easy: These puppies aren't born yet. Pregnant dog X-ray by Shutterstock

2 to 5 weeks old: The eyes open at two to three weeks of age although vision is poor. There will still be no teeth present. Puppies this age become more engaged with their environment and begin to explore their surroundings.

5 to 8 weeks old: This period is marked by the eruption of deciduous (baby) teeth. Yes, that's right: Dogs, like humans, have two sets of teeth. The first set begins to erupt at five to six weeks of age, and the full set is generally in place by eight weeks. These teeth are very sharp, and people with puppies in this age group will be painfully familiar with them. By the time a puppy is eight weeks old he or she will be in full-on puppy mode with periods of active playing, exploring, chewing mixed with periods of passed-out sleep.

8 to 16 weeks old: The deciduous teeth are in place, but the space between them will increase as the jaw and face grow. They will also begin to appear disproportionately small since they stay the same size while the puppy grows around them. This is a period of intense activity, growth, exploration, and learning for the puppy.

16 weeks to 8 months old: At around 16 weeks the baby teeth begin to fall out and be replaced by permanent teeth. This process starts at the front of the mouth with the small teeth called incisors, and then works its way back, generally in a symmetrical fashion. The puppy's mouth may bleed slightly (or his or her breath may sometimes smell like blood) as the baby teeth fall out. The deciduous teeth are generally gone by five months, and the permanent teeth generally are fully erupted by eight to 12 months of age.

You can't tell how old a dog is just by looking at the outside. Photo of Dr. Eric Barchas by Liz Acosta.

8 months to 24 months old: Most dogs have reached their full height by eight to 12 months of age (although some giant breeds continue to grow for up to two years). They are adolescents -- not quite puppies, but not quite mature dogs. Like adolescents, dogs in this age group go through puberty (if they aren't neutered or spayed). And like adolescents, they are generally clumsy and awkward and they may have skin problems (puppy mange often strikes around this time, or sometimes a bit earlier).

2 to 3 years old: Most dogs' physical development is complete by two years of age. Alas, it often is not long after this that time to begin to take its toll. The first sign of aging usually is visible in the mouth: dental calculus and even gingivitis will be present in the majority of dogs by three years of age if their teeth aren't brushed.

3 to 7 years old: Humans this age would be considered in the prime of their lives. However, some signs of aging will occur during this time. Dogs whose teeth do not receive attention (either through brushing or professional dental work) will generally experience progressive dental disease. Gray hairs may develop on the muzzle. Activity levels will slow.

From 3 to 7 years old, dogs slow a bit, but they are still pretty active. A Labrador Retriever on the beach by Shutterstock.

7 years and beyond: As I mentioned above, different sizes of dogs age at different rates. Seven years is generally the time at which these differences become pronounced. Many larger breeds of dogs will show significant signs of arthritis (manifested by mobility problems), while smaller dogs may not exhibit these issues for another three to five years. At seven years of age most dogs' eyes will become slightly cloudy. This natural aging phenomenon is a type of cataract, but it does not significantly compromise vision or quality of life. They may develop wart-like growths on their skin (similar to moles in people), or soft growths called lipomas underneath the skin. Their voices may change to a raspier tone. Smaller dogs may begin to show symptoms of collapsing trachea (manifested most frequently by coughing when active). Hearing and vision may fail (although the vision loss is not usually linked to the cloudiness in the eyes). Mobility may progressively deteriorate. Dental disease may become profound and if the mouth is not cared for teeth may fall out.

How to keep your dog young

As mentioned above, genetics (especially breed) plays a significant role in the rate at which dogs age. However, so does lifestyle. Two of the hallmarks of aging are dental disease and mobility concerns. Therefore, one of the simplest ways to slow the aging process is to take care of your dog's teeth by brushing them at least daily and seeking professional dental care when needed. Another way is to keep your dog active and control his or her weight. Active dogs whose weights are ideal are less likely to experience symptoms of arthritis, collapsing trachea, and the other ravages of aging.

Does the 7-to-1 rule work?

Conventional wisdom holds that one dog year is the equivalent of seven human years. As this article illustrates, that conventional wisdom is not exactly correct. The first two years of a dog's life are roughly equivalent to 21 years in human. The rate of aging varies significantly thereafter, primarily based upon a dog's size. A Great Dane may age 10 to 12 "human" years for each subsequent year, whereas a teacup Poodle may age only at a ratio of about 5-to-1.

As your dog ages I recommend that you not lose track of an important notion. Getting old may not be fun, but it generally beats the alternative.

Ask a Vet: How Can You Tell How Old a Cat or Kitten Is?

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Ask a Vet: How Can You Tell How Old a Cat or Kitten Is?

Cats age at different rates based on lifestyle and genetics, but there are still ways to determine age.

Dr. Eric Barchas  |  Oct 10th 2013  |   5 Contributions

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Conventional wisdom holds that each year for a cat is equivalent to seven years of development and aging for a person. Or that each cat year is equivalent to five human years. Or that the first two years are equivalent to 21 years, and each subsequent year is equivalent to four or five years. Or that 20 years old in a cat is equivalent to 100 in a person.

It's easy if your cat is a kitten, but how do you tell her age when she's grown? Kitten gets a vaccination by Shutterstock.

Any time that conventional wisdom holds so many potentially contradictory views, you can count on the convention not to be especially wise. The many rules of thumb that are available to compare cat ages to human ages are usually based upon total life expectancy. An average cat's life expectancy is around 17 years, and a human's is around 84 years. This leads to a rough equivalency of five-to-one. But it is not an apples-to-apples comparison. Feline development and aging are not directly comparable to ours.

Three-day-old kitten in a woman's hands by Shutterstock

Nonetheless, feline development and aging are of great interest to anyone who has a cat. Most cats' birthdays are not known exactly, and people are often curious about how to determine a cat's or a kitten's age. It takes a significant amount of experience to get good at it, and different cats develop and age at different rates depending upon genetics and lifestyle. However, there are some rules of thumb that can help people estimate their feline friend's age as well as know what to expect as their cat progresses through his or her life.

Kitten development

Birth to 1 week old: Kittens are born toothless and with their eyes closed. They spend almost all of their time during their first week of life rooting, suckling and sleeping.

1 week to 3 weeks old: Some kittens begin to open their eyes at around one week of age; most will have open eyes by two weeks of age. Generally they will remain toothless during this time. Their activity will still be quite limited during this time. The deciduous (baby) teeth begin to erupt at around three weeks of age.

That's easy. Your cat isn't born yet. Pregnant cat sitting on a table by Shutterstock

3 weeks to 5 weeks old: The deciduous teeth continue to erupt through this time, and the canine teeth (the fangs) make their pointy appearance. Kittens become more active and engaged in their environments but they are significantly uncoordinated. They also become devastatingly cute. Most kittens will have blue eyes until they are at least five weeks old.

5 weeks to 8 weeks old: The baby teeth are fully erupted and individuals will be in full-on kitten mode. Coordination starts to improve. The eyes change to their adult color (unless the kitten is destined to be blue-eyed). Crucially, the prime window for socialization begins to close; kittens that have their first human contact after eight weeks may be harder to socialize.

8 weeks to 16 weeks old: This is prime kittenhood. It is a period of significant growth, play, and exploration. The deciduous teeth may appear to space out and be outgrown towards the end of this period. The deciduous teeth begin to fall out at around 16 weeks in most individuals, beginning at the front of the mouth and working symmetrically towards the back. The adult teeth begin erupt to replace the kitten teeth.

16 weeks to 7 months old: The adult teeth complete their eruption. Many kittens become more confident and assertive. Coordination improves significantly, and rapid growth occurs.

7 months to 18 months old: This period is equivalent to adolescence in humans. Puberty occurs in cats who have not been spayed or neutered. Cats reach their adult height and length, and then fill out to their healthy adult weight -- and sometimes beyond it.

Orange short-haired cat by Shutterstock.

Adult aging

18 months to 3 years old: Young adulthood. These years are roughly equivalent to a human's 20s. Health is generally good, and minimal signs of aging are noted. However, just as some twentysomething people start to show some signs of less-than-perfect health, some cats in this age range will develop dental calculus and gingivitis. Some cats also develop weight problems during this time.

3 years to 7 years old: Prime adulthood. Health problems (other than dental disease and obesity-related issues) are rare. Activity levels are still high. Cats remain agile and limber. However, most cats who don't benefit from dental care (tooth brushing or regular professional dental work) will develop significant dental disease during this time.

7 years to 14 years old: This period roughly corresponds to middle age for cats. Cats in this group are not exactly old, but health problems such as kidney failure and hyperthyroidism may develop. The body will show signs of aging. The pupils of cats' eyes generally develop a slight blue or grey tinge at around seven years of age; this becomes more prominent as cats age but it does not significantly compromise vision or quality of life. The hair may become less supple and may be noted to clump together. Dental disease will usually be pronounced in cats who have not received dental care. The bones become less flexible; owners of cats in this age range may notice that their pets' ribs seem harder and less flexible. Signs of arthritis may develop.

14 years and beyond: Cats in this age group are senior citizens. The aging processes that began in middle age progress. Dental disease may become profound and teeth may fall out. The pupils of the eyes will have a significant grey tinge. Mobility may become compromised, and activity decreases. Clumping of the hair becomes more pronounced and may lead to matting. The bones will be brittle, and the ribs will be firm. Age-related illnesses such as kidney failure and cancer unfortunately become common. The voice may become noticeably raspy or hoarse. There may be evidence of hearing or vision loss, although poor eyesight is not generally related to the greying of the pupils.

Gray long-haired cat by Shutterstock.

How to slow the aging process in cats

Although the above guidelines apply to most cats, there are significant variations in aging rate among individuals. Much of the variation is genetic, but a substantial portion is lifestyle-dependent.

Here is an analogy. I used to work near a coffee shop. One of the shop's regular patrons spent every afternoon basking in the sun and smoking cigarettes on the shop's porch. She may have been 40 or she may have been 70; I couldn't tell because her lifestyle had so ravaged her body. Similarly, five-year-old feral, intact, FIV positive cats who continuously fight may have rotten mouths and hair qualities that make them look 15 years old. Well-cared-for house cats can seem five years younger than they are.

Two of the leading concerns that occur as cats age are dental disease and mobility concerns. Regular dental care, through tooth brushing or regular professional dental work, helps to slow the aging of the mouth. Maintenance of a healthy weigh promotes flexibility and mobility and reduces the impact of arthritis.

Finally, infectious disease in cats can take a significant toll and contribute substantially to aging. Indoor cats are at lower risk than their outdoor counterparts, and indoor cats have longer life expectancies (on average) than their outdoor counterparts.