Thursday, January 6, 2011

Anatomy of the Feline Mouth

As a cats-only practitioner, I don’t mind when people say that I’m looking down in the mouth, because the feline mouth is fascinating. Cats use their mouths for a lot of things – eating, drinking, grooming, and communication. Although cats breathe mainly through their nose, the mouth provides an additional passageway for air to enter the lungs.

Cats are true carnivores, and this is reflected in their mouths and teeth. The teeth are responsible for tearing, cutting, and grinding food into pieces small enough to swallow. Feline teeth are also used as weapons, both offensively (for example, hunting) and defensively (as when I foolishly try to insert a thermometer into a cat who does not want his temperature taken).

Cats are “diphyodont”, which means they have two sets of teeth, the deciduous (“baby”) teeth which are shed and are replaced by the second, permanent set. Kittens are born with no teeth. At about 3 to 4 weeks of age, the deciduous teeth begin to erupt. By 6 weeks of age, all 26 deciduous teeth are present. At 4 to 5 months of age, the deciduous teeth are lost and the permanent teeth erupt. By six months, all of the adult teeth will have erupted.

Adult cats have four types of teeth. They are the incisors, the canines, the premolars, and the molars. In the upper jaw (the maxilla), there are 6 little incisors, two canines (the “fangs”), three premolars, and one molar. The incisors are used mainly for picking up objects and for grooming. The canines are used for holding prey, and for slashing and tearing when fighting. Premolars function mainly for breaking food into small pieces, as well as for carrying and holding. The molars have flat surfaces and are used to grind food into small pieces. In the lower jaw (the mandible) you’ll find the same number of incisors, canines and molars, however, there are only two premolars instead of three. The total number of permanent teeth in a cat is 30. (Adult dogs have 42 teeth, in case you’re wondering.)

The teeth themselves have their own anatomy. Every tooth has a crown – the part of the tooth visible above the gums – and a root, which is located below the gums. The root of a tooth is embedded in the alveolus – the “socket” in the jaw bone. Roots are tightly attached to the alveolus by a ligament called the periodontal ligament. Some teeth, like the canines, have only one root, while the largest upper premolar (also known as the “carnassial” tooth) has three roots. The roots of the upper teeth are anchored in the maxilla; those of the lower teeth are anchored in the mandible.

In the central core of the tooth is called the pulp, and it contains most of the nerves and blood vessels of the tooth. Pulp is the only soft tissue of the tooth. The blood vessels nourish the tooth, while the nerves transmit heat, cold, and pain sensation. Surrounding the pulp is the dentin, which makes up the majority of the tooth and is responsible for a tooth’s white/ivory color. The dentin that makes up the crown of the tooth is covered in enamel. Enamel is the hardest tissue in the body.

The tongue is a muscular organ that has several functions, the main ones being the guiding of food and water into the mouth, and for taste sensation. The tongue assists in the chewing and swallowing of the food as well. Queens use their tongue to stimulate urination and defecation in kittens by licking the genital area. The tongue also may play a role in reducing body temperature in the cat. Dogs are well known for panting, but when the ambient temperature is particularly hot, cats will also pant. As air passes over the tongue, the air is cooled. Saliva augments this process as it evaporates.

The tongue of the cat differs from that of the dog in several ways. In the center of the tongue are papillae – small hair-like projections that act as small hooks. They are responsible for that “sandpaper” feel when cat licks our skin. These papillae are made of keratin, the same material found in human hair and fingernails. The papillae serve several purposes. They are important in grooming the fur. They assist in gathering and holding food inside the mouth. Specialized papillae at the tip and the sides of the tongue play an important role in taste sensation. Studies have shown that the feline tongue can sense texture as well as flavor, and this may explain why some cats prefer dry foods based on their shape. The feline tongue is very sensitive to temperature, and studies have shown that cats prefer food served at room temperature than chilled or warmed food. Many of my clients have told me that once they put leftover canned food in the refrigerator, their cat won’t eat it unless they microwave it back to room temperature.

Disorders of the mouth – dental problems in particular – are amongst the most common medical conditions seen in pet cats. If untreated, dental disorders can lead to bad breath, swollen and bleeding gums, loose teeth, oral pain, and difficulty eating. By nature, cats are very secretive, and it can be tricky to tell if a cat is experiencing oral discomfort. Sometimes, a cat will indicate that their mouth is hurting by pawing at their mouths, drooling, or deliberately turning their heads to one side as they eat to avoid chewing on the side that is painful. Some cats will completely stop eating due to dental pain. Others may stop eating dry food and only eat wet food. This is often misinterpreted as the cat becoming “finicky” about their food, when in actuality, they would prefer to eat the dry food but can’t because it’s become painful to crunch on kibble. Dental disorders can have consequences in other parts of the body, because bacteria in dental tartar can enter the bloodstream through the inflamed gums. These bacteria may infect the heart valves and kidneys.

By taking care of your cat’s mouth and teeth, you’re helping care for his overall health. Regular veterinary checkups and follow-up exams are necessary to maintain good oral health.
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