How to Age Babies

It’s that time of year when people start finding little kittens. Veterinary hospitals, animal shelters and rescues are always getting questions regarding on how old these found kittens are. There are a few tricks of the trade that can help determine the relative age of these babies. While we are talking about ages of the young, I will also go over puppy ages as well. There are a few key features that a person will examine to estimate the age of an adorable ball of fur. By examining the baby’s teeth, eyes, ears and weight; a person can get a decent estimate of how old it is.

First, let’s go over a few terms:
Deciduous teeth – are the “baby” teeth

Incisors – the six teeth that are the front of the mouth in between the canines.

Canine teeth – are the four long teeth that sits besides the incisors.




A great starting point to know if you have found a kitten is when kittens are born their ears and eyes are sealed shut. Also, they have no visible teeth. Remember, if a kitten is sick, they too can have their eyes sealed shut but for an entirely different reason so that is why it is important to assess all of the features.


7-10 days after birth

Eyes begin to open. Ears are still close to the head.



Between 2 – 3 weeks after birth

Deciduous teeth are coming in. Ears are starting to stand upright but the tips are still pointed towards the head. The eyes are blue.


4 – 5 weeks of age

All deciduous teeth are in. Kittens have 26 deciduous teeth. Ears are now standing upright like an adult cat’s ears. Eyes are still blue. If the kitten is relatively healthy and has been eating properly, they should weigh one pound at one month of age. A good rule of thumb is one pound equals one month of age up until they are about 5-6 months of age.

7-8 weeks of age

Eyes change from blue to their adult eye color. After this point, you will have to rely on the teeth and weight.

Between 3 ½ – 4 ½ months old

Permanent incisors come in.


5 months of age

Permanent canines erupt.


6 – 7 months of age

By the end of 6 months into their seventh month, the kitten should have all of their adult teeth in. There is a total of 30 teeth.


8 months and older

As the kitten nears adulthood, it becomes harder to estimate how old a kitten is.




You are less likely to find a very young puppy roaming around by itself like you would with a kitten due to the fact that there isn’t a high “wild” population of feral dogs. Puppies have a few similar features to age them like you can a kitten but there are a few traits to keep in mind. The breed of dog will affect how the ears lay on the head and what can happen with their teeth. Large breed dogs tend to have their teeth erupt more rapidly than those of smaller breeds. Smaller breeds tend to retain their deciduous teeth, and this can affect their adult teeth.



Eyes are sealed shut. Ear canals are closed.


7 – 10 days old

Eyes are now open. Ear canals have been open.




3 – 4 weeks old

Deciduous teeth are coming in.


6 weeks

All deciduous teeth are in.


4 -5 months of age

Permanent incisors are coming in.


6 months of age

Permanent canines come in.


7 months of age

By the end of the pup’s seventh month, all permanent teeth are in. A dog has 42 permanent teeth.


8 months and older

After the pup’s permanent teeth are in, chewing habits, diet, and mouth structure makes it much more difficult to age a dog by its teeth.


Although, we have to guess the age of a stray animal there are a few clues to help narrow down the age range. This blog article is just a start to help you with getting started caring for the furbaby, you should still take the furbaby to a veterinarian to make sure it is receiving the proper care and diet.



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