Quick Take
- Rats have a unique anatomy that means that their jaw muscles run behind their eyeballs.
- Rats have to grind their incisors to stop them growing too long; this is called bruxism.
- When rats brux, their eyeballs vibrate.
- Generally, eye boggling means a rat is happy, but it can mean that they are stressed.
The first time you see a rat boggling its eyes, it can be a startling sight. Their eyeballs visibly vibrate in their sockets. It’s not surprising that many novice pet rat owners assume something is wrong with their rats. In fact, eye-boggling is a perfectly normal rat behavior. Let’s take a closer look at how and, more importantly, why rats do this!
Boggling and Bruxism
Bruxism is the scientific name for tooth grinding. Many animals do it, including humans. Rats can repetitively grind their incisors against each other. To do this, they use their jaw muscles. Thanks to their unique anatomy, some of the jaw muscles attach near the back of the eye socket. When these muscles contract and relax during bruxism, they can cause the eyeballs to vibrate.
Why Do Rats Brux?
Unlike our teeth, rodent teeth are constantly growing. They have stem cells at the base of each tooth in areas called cervical loops. These stem cells continuously produce new cells that mineralize and lengthen the tooth. The rat has to continuously gnaw things to keep them sharp and at a manageable size.
Rat incisors never stop growing.
©daniiD/Shutterstock.com
Bruxing also helps wear down their teeth, and rats tend to do it when they are relaxed and content. So, if you see your rat boggling, it generally means that they are in a state of bliss. However, the opposite can also be true. Sometimes rats brux, and therefore boggle, when they are anxious, stressed, or in pain.
Check the Context
To figure out whether your pet rat’s boggling is a good thing or a bad thing, you need to take into account the context. If your rat is boggling, not eating or drinking, and behaving in other strange ways, there is cause for concern. Take them to be checked out by your vet. On the other hand, if your rat appears relaxed and content while boggling—such as when being petted, playing with a favorite toy, or eating a tasty treat—they are likely very happy!
