When owners bring their new puppy 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.

Puppies, like human babies, are born without teeth. Only the gum surface is visible. This allows them to nurse without hurting the mother. When they reach 30 days of age, their deciduous or temporary (baby) teeth start to break through the gums. This is referred to as "erupting." Puppies have a total of 28 deciduous teeth by the time they reach 45 days of age. This is a good time to give puppies plenty of chew toys.

As time goes by, these teeth are replaced by permanent teeth. The canine tooth fairy works somewhat faster than her human counterpart – most breeds show permanent teeth at 6 to 7 months of age.

Eruption of the permanent teeth is as follows:

Incisors

Central: 2-5 months
Intermediate: 2-5 months
Corner: 4-5 months

Canines

5 months

Premolars

First: 4-5 months
Second: 6 months
Third: 6 months
Fourth: 4-5 months

Molars

First: 5-6 months
Second: 6-7 months
Third: 6-7 months

The Formulas

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

Puppies will have a total of 28 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 puppy dental formula is 2 (I 3/3 C1/1 PM 3/3)= 28 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 dogs is 2(I 3/3 C1/1 PM 4/4 M2/3) = 42 teeth.

The letters stand for incisor, canine, premolar and molar. Most breeds will show permanent teeth between the ages of 6 to 7 months of age. Larger breeds have a tendency for early eruptions compared to the smaller breeds.

So, if a puppy has his permanent canines and first molar we can estimate his age to be 5 months.

Dental Care

Your veterinarian will examine your puppy'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 is key to your dog's general health. Start early handling your puppy's mouth to keep it clean and brushed. Use gauze initially, then switch to a finger brush, then a toothbrush. Brushing a minimum of three times a week will prevent early gingivitis and periodontal disease later in your dog's life.