Posted: December 24, 2014, 6:35 p.m. EST
© Courtesy Leticia Materi, PhD, DVM
To know what is abnormal, it helps to compare against what is normal. The above images show normal incisors and normal cheek teeth for a rabbit.
One of the most common ailments in rabbits that we see at our clinic is dental disease. It is a bit of a daunting topic for a single small blog entry because entire textbooks have been written on the subject. My plan is to examine rabbit dental problems over the next few entries in the hope of shedding some light on this ailment. To understand why dental problems can occur, it is important to comprehend the anatomy and function of normal rabbit teeth.
Rabbit Tooth Anatomy
Baby rabbits have a temporary set of teeth that are lost either just before or just after birth. Permanent teeth begin to erupt during the first five weeks of life. As difficult as it might be to believe, an adult rabbit has 28 teeth in total. Each tooth is essentially comprised of two parts. The part of the tooth that we can see in the mouth is often called the crown. The portion of tooth that lies beneath the gumline is referred to as the root. To examine the root, veterinarians rely on diagnostic imaging techniques such as X-rays.
All of these teeth continuously grow throughout the lifetime of the rabbit. The easiest teeth to examine are the incisors. These are the very front teeth that we can see if we gently lift the rabbit’s lips. What separates rabbits from rodents is the presence of a tiny pair of upper incisors that exist behind the larger incisors. These little incisors are often called the peg teeth. Special instruments are needed to visualize the teeth at the back of the mouth. These back teeth are often called the cheek teeth.
Rabbit Tooth Action
When the mouth is closed, the lower incisors normally rest just behind the upper incisors. Rabbits will periodically grind their teeth while at rest. This movement, combined with the placement of the lower incisors behind the upper incisors, allows for the incisor tips to be shaped like a chisel. The incisors allow rabbits to grab and tear off pieces of food as well as gnaw through roots if digging a burrow. However, most of the work of chewing food is accomplished by the cheek teeth.
As stated before, all of the incisors and cheek teeth are constantly growing, which means that a rabbit must constantly grind them down to prevent them from becoming too long. Studies have shown that the incisors can grow up to 2 to 2.4 millimeters per week, and how well a rabbit can grind down the teeth is heavily influenced by diet.
Here is what happens when rabbits eat certain foods:
Carrots: In order to eat carrots, rabbits rely on crushing, which means that the jaw moves up and down. Because the force is vertical, minimal grinding can occur.
Hay: Hay is chewed using a shearing action, which means that the jaw moves side-to-side in a complex "figure 8” pattern. This provides maximal grinding forces.
Pellets: Eating pellets provides both crushing and shearing actions.
This underscores the importance of hay in the diet. In addition to promoting normal gastrointestinal movement, hay is critical for the maintenance of healthy teeth in a rabbit.
In the next blog entry, we will begin to examine dental disease.
Note: This article is meant for educational purposes only and in no way represents any particular individual or case. It is not for diagnostic purposes. If your pet is sick, please take him or her to a veterinarian.
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