The oral cavity of the dog and cat

Muzzle… or mouth?

A dog has a mouth, and a cat has a mouth! The difference between the two ? Their capacity to open. When open, the mouth of a cat is more of a slit than the mouth of the dog, and less teeth are visible.

How many teeth does my cat or dog have ?

Just like humans, our pets have 2 generations of teeth: the deciduous – or baby – teeth and the permanent teeth.

The deciduous teeth appear at around 3 weeks of age. There are 26 deciduous teeth in kittens and 28 in puppies, distributed as follows :

• 12 incisors – 6 in the upper jaw and 6 in the lower jaw;
• 4 canines – 2 in the upper jaw and 2 in the lower jaw;
• 10 or 12 premolars, depending on the species – 6 in the upper jaw and 4 or 6 in the lower jaw.

These will gradually fall out from 3 to 4 months of age to make way for the final set of teeth, which will be completed at 6-7 months. For some breeds, such as the Chihuahua, this takes longer.

In adults, the number of teeth increases to 30 in cats and 42 in dogs:

• 12 incisors – 6 in the upper jaw and 6 in the lower jaw;
• 4 canines – 2 in the upper jaw and 2 in the lower jaw;
• 10 or 16 premolars, depending on the species – 6 or 8 in the upper jaw and 4 or 8 in the lower jaw;
• 4 or 10 molars, depending on the species – 2 or 4 in the upper jaw and 2 or 6 in the lower jaw.

These teeth have different shapes and therefore different functions.

What exactly is a tooth ?

A tooth is mostly made up of dentin – a hard structure formed by specific cells called odontoblasts. It consists of 3 distinct layers:

• Primary dentin, which is formed during the development of the tooth;
• Secondary dentin, which is deposited on top once the root of the tooth is formed, and is a sign of normal tooth ageing;
• Tertiary dentin, which is formed during the repair process.

At the heart of this dentin is the dental pulp. This contains nerves, various vessels, connective tissue and odontoblasts.

The exposed part of the tooth is covered with enamel. This very hard tissue is formed by cells – the ameloblasts – only before the tooth emerges. In our four-legged friends, the thickness of the enamel varies between 0.1 mm and 1 mm.

The root, the non-visible part of the tooth, is covered by a bone-like tissue called cementum.

The tooth is supported by the periodontium, which includes the gum, cementum, alveolar bone and the periodontal ligament. The periodontal ligament surrounds the entire buried part of the tooth and is attached to the cementum – the tooth side – and the alveolar bone. It keeps the tooth in the socket.

Finally, the area between the tooth and the gum is called the gum line. The depth of this groove varies – physiologically – between 0 and 1 mm in cats and 0 and 3 mm in dogs.