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How Old is This Kitten?

When owners bring their new kitten to a veterinary practice, one of the first questions is: Can you tell me how old s/he is? The answer lies in the mouths of these babes.

Kittens, like human babies, are born without teeth. Only the gum surface can be seen. This allows them to nurse without hurting the mother. When they reach 25 to 30 days old their deciduous or temporary (baby) teeth start to break through the gums, which is referred to as “erupting.” Kittens have a total of 26 deciduous teeth by the time they reach 45 days of age.

As time goes by, these teeth are replaced by permanent teeth. The feline tooth fairy works somewhat faster than her human counterpart – most breeds show permanent teeth at 6 months of age.

Eruption of the permanent teeth is as follows:


Central: 3-4 months
Intermediate: 3-4 months
Corner: 4-5 months


5 months


Second: 5 months
Third: 5-6 months
Fourth: 5-6 months


First: 4-5 months

The Formulas

Following a complicated formula (which, for the more intrepid is included below), veterinarians can estimate the age of a kitten by the number of permanent versus deciduous teeth.

Kittens will have a total of 26 baby teeth by the time they reach 45 days of age. The dental formula for baby teeth lists the number of each type of tooth and whether that tooth is on the top jaw or lower jaw. The kitten dental formula is as follow: 2 (I 3/3 C 1/1 PM 3/2) = 26 teeth.

The I in the formula stands for incisor. The C stands for canine and PM stands for premolars. There are no baby molars. The top number is the number of teeth in the upper jaw. The bottom number is the number of teeth in the lower jaw. The dental formula lists the teeth only on 1/2 of the mouth. The right and left side are the same. This is the reason for the number 2 before the formula.

After the baby teeth are lost, permanent teeth erupt. The permanent dental formula for cats is 2(I 3/3 C1/1 PM 3/2 M 1/1) = 30 teeth.

The letters stand for incisor, canine, premolar and molar.

For example if a kitten has his permanent canines and first molars we can estimate his age to be 5 months.

Dental Care

Your veterinarian will examine your kitten’s mouth at every visit starting at 45 days of age and through 6 to 7 months of age. This will help to determine any problems during the eruption of the permanent teeth. Some of these include: extra teeth, malocclusion and retained deciduous (baby teeth).

Dental health and regular brushing is key to your cat’s general health. Start brushing early in your kitten’s life by using gauze, then switch to a finger brush. Brushing a minimum of three times a week will prevent early feline resorptive lesions, gingivitis and periodontal disease later in your cat’s life.