Rat eye bulging and other health behaviors: When should you be concerned?

As with every pet owner, you’re bound to worry about the health of your rat at some point. Maybe that worry is triggered by odd behavior, unusual eating patterns, or changes in your rat’s appearance. To be sure, it is the habit of a good pet owner to keep tabs on their pets’ behavior and happiness. There may be times when your vigilance and attention to detail can help you notice an illness or other issue early on, making it possible to quickly get your rat the medical care he/she needs. However, if you’re concerned with every tiny change in behavior or appearance, you can drive yourself crazy with worry over your pet’s health. Here’s how to distinguish between normal rat behavior and troubling signs of sickness.

Eye bulging

rat eye bulging

Particularly newer rat owners may be surprised and a little unsettled when they see their rat’s eyes bulge out of the sockets. But rat eye bulging, to some extent, is part of normal rat behavior. Rats can move their eyes in and out of their sockets, giving the appearance of bulging or “boggling.” Most of the time, there’s nothing to be concerned about. Your rat simply has different eye motions than you have, and is making use of these differences. Typically, normal eye bulging occurs while a rat is grinding his/her teeth — which can either be a sign of contentedness or stress. Based on your rat’s other behaviors, you should be able to deduce whether s/he is happy or distressed. In either case, this type of eye bulging is a normal behavior and nothing to worry over.

However, there are times when rat eye bulging should be a cause for concern. Extremely bulged eyes can be a sign of infection. In fact, eye bulging is one of the later stages of eye infection in rats, and may signal a severe problem. If your rat does have an eye infection, the eye bulging will almost always be accompanied by at least one additional symptom. A healthy rat’s eyes will be bright and clear, with no signs of pus around the edges. The most common symptoms of eye infection include puffiness in the eyelids, redness around the eyes, or discharge (pus) from the eyes. You may also notice that one eye is significantly more swollen than the other — which would indicate that the swollen eye is not functioning properly — or that your rat’s eyes are itchy, leading to irritation and excessive scratching.

If you see any of these additional symptoms, it is best to take your rat to the veterinarian as soon as possible. Untreated eye infections can lead to permanent damage, such as blindness. However, if you take your rat for treatment sooner rather than later, your veterinarian can prescribe antibiotics to break up the infection and resolve it before it causes greater problems.

Red eye discharge

Speaking of rat eye bulging, there is one other normal eye pattern in rats that can be disconcerting to owners. Rats may occasionally have a red discharge from their eyes, which resembles red tears or even blood. This is called porphyrin, a compound that is produced by a gland and then drains to the area around a rat’s eyes. Small amounts of occasional porphyrin discharge is normal, and is nothing to worry about — it’s simply a normal function of your rat’s system. However, the gland that produced porphyrin can at times have issues with overproducing, leading to excessive discharge and to discharge that hardens around the eyes into a red crust. This is usually an indication that your rat’s general health has declined, that s/he is not being properly fed or is not being allowed to sleep adequately each night.

If you notice excessive porphyrin excretion in your rat, assess your rat’s overall health and wellbeing, and make any necessary adjustments. Are you supplying your rat with the proper food? Are you providing your rat with a calm enough environment to allow for relaxation and sleep? If you can identify one of these areas that your rat is not being given the best wellness level, make the necessary adjustments and you should see a return to normal porphyrin production.


Like other animals, and even like humans, rats will get itchy from time to time. They’ll scratch their skin in response to minor itches, just as you might scratch your arm or your leg to get rid of an itch. And, just like most of your minor itches, many of a rat’s small itches are inconsequential. In addition, rats also groom themselves with their toes, which may look like they’re scratching an unidentified itch. This is also normal behavior, which you’ve likely noticed in your rat for as long as you’ve owned him/her. Isolated instances of scratching and reasonable amounts of grooming are absolutely normal and even expected for your rat.

rat scratching

However, there are times when excessive scratching can be the first symptom of a problem. If you begin to notice that your rat scratches or grooms for much longer than s/he used to, this may be cause for concern. One way to identify whether the scratching is normal behavior is to observe your rat and see if the itchiness disturbs play or sleep periods. If your rat can’t rummage around the play area without constantly stopping to scratch an itch, there’s likely a health issue of some sort.

The most common cause of excessive scratching is mites, although lice and fleas also make it to the top of the list. If you suspect that your rat has mites, take him/her to the veterinarian for proper diagnosis and treatment. Mites are easily treated, although you should also remove and replace all of the bedding in your rat’s cage in order to ensure that the mites are gone. If you’re worried about mites coming back, you can begin using specialized shampoos and home remedies to prevent the mites from returning.

In addition to parasites on your rat’s fur, your rat’s excessive itching may simply be caused by an environmental irritation. Just as humans can have sensitive skin, or allergies to certain fabrics or shampoos, rats can also have irritations from the things being used in their cages. For instance, if you notice excessive scratching after you’ve switched bedding brands, then your rat may be allergic or sensitive to some material that is in the new bedding. If possible, try to revert to any old materials that you used (bedding, shampoo, even new toys in the cage) before your rat began scratching. Give your rat several days to adjust back after you make this switch. If the scratching still continues, then consider taking your pet to the veterinarian for an exam.

Teeth grinding

rat teeth grinding

Your rat’s teeth are different than your own. Rat incisors grow continuously over the course of their lives, which allows them to use their incisors without wearing them down. However, this constant growth also means that the incisors can get way too long if they are not being used enough. To deal with this, rats often grind their teeth together, wearing their incisors down to a normal, useable length. 

So, if you hear that your rat is grinding its teeth, there’s likely nothing to be concerned about. However, you may want to ensure that your rat is comfortable and happy, as sometimes rats grind their teeth when they feel distressed.

On the other hand, if you haven’t heard your rat grind his/her teeth in a while, especially if s/he hasn’t been gnawing on other things, this may be a cause for concern. When a rat doesn’t grind his/her teeth, the incisors can get excessively long and essentially become unuseable. If you’re worried about your rat’s teeth, take a peek and check for several things. Look at the incisors and note the length. If they seem uneven, longer than usual, or are even beginning to poke holes through your rat’s cheeks, this is a reason to bring your rat to the veterinarian. The teeth may simply need to be manually filed down, in order to put your rat’s oral health back in alignment.

In addition, if you notice any signs of redness, swelling, or pus/discharge in your rat’s mouth or around your rat’s teeth, this is also a legitimate reason to worry. As with your rat’s eyes, these symptoms in your rat’s mouth are a likely indication of an oral infection. A veterinarian can prescribe antibiotics to fight the infection, but these are most effective if they are administered soon after the infection has taken hold. If left untreated, oral infections can lead to serious problems for your rat, possibly leading to a systemic infection (which can be fatal) or to your rat’s inability to eat food or drink water.


Being a rat owner comes with its own specific difficulties and rewards. In all cases, if you suspect that your rat is ill or otherwise unwell, it’s best to make an appointment with your veterinarian. Even experienced rat owners may not always be able to prevent illnesses or injuries with their rats, but speedy treatment from a veterinarian can resolve most issues before they become severe or cause permanent damage.

(Last Updated On: December 28, 2017)

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