The Tooth about Rabbits and Rodents

Ever stop and wonder; why do my hair and fingernails keep growing, but my teeth do not? No? Just us? Well if you were a rabbit or a rodent, they would!

Rodent teeth are sometimes referred to as ‘open-rooted’ because they continuously produce more tooth. In mice and rats, just the front teeth (incisors) continuously grow.  In rabbits, guinea pigs, and chinchillas, all the teeth keep growing! 

Want some more neat tooth facts?  Rabbits, guinea pigs, and chinchillas all have very unique crowns, or tops of their teeth (the part we can see). Guinea pig cheek teeth grow at an angle, because their lower jaw (mandible) is wider than their upper jaw (maxilla), so when you look inside their mouth it feels like everything is falling over.  Chinchilla teeth have very short crowns, so it’s a little tricky to see their cheek teeth at all!  Rabbits have a bonus pair of little incisors that sit right behind their main incisors.  These are called peg teeth, and they help keep the lower incisors wearing appropriately.   

So if the teeth keep growing, why don’t our pets need their teeth cut like their nails or fur?  These animals all spend a lot of their time chewing, and so they grind down their teeth as they grow. In fact, if their teeth stopped growing, they would grind their teeth away completely! But in some cases, we do actually need to trim a pet’s teeth.  If a rabbit or rat has a bad overbite their teeth don’t line up, and so they don’t wear down the way they are supposed to. In these cases, we need to trim their teeth regularly to make sure they don’t get too long and prevent our pet from eating.  

While historically we always assumed it was just the chewing motion alone that kept rabbit and rodent teeth in check, there is also evidence that the mineral content (such as calcium) of their diet plays an important role.  If the minerals aren’t right, the teeth grow weak and start to bend rather than grind down. A tooth that is bending the wrong way and continuing to grow is a problem indeed! This is one reason we recommend that our rabbits, guinea pigs, and chinchillas always have access to timothy hay 24/7.  

Along with the tooth growing too long at the crown, the root of the tooth inside the jaw can also overgrow.  So-called retrograde growth is a serious problem, as the roots of the teeth can impact other structures in the skull, and form abscesses (infections).  Signs of the upper teeth roots overgrowing include eye discharge, because the overgrown root can block normal eye drainage.  Signs of lower teeth roots overgrowing include a bumpy lower jaw, where the roots are pushing out the bone.  

One very common sign of dental disease in rodents and rabbits is drooling; which you may notice as a wet chin.  As the disease progresses, our animals will stop eating.  Be sure to contact us right away if you think your rabbit or rodent is drooling or not eating well! 

-Dr. Cosimini