There are two main reasons why pet rats are brought to see their exotics vets. The first one is for tumors (usually mammary), and the second one is for breathing problems. Both can be quite serious but breathing issues are usually more acute and require a quick approach to treatment.
Rats can have several reasons for breathing problems. Choice of bedding, unclean environments, and diseases can all cause respiratory distress in your pet rat. Let's take a look at some of the more common reasons for breathing problems in pet rats.
This is a bacteria that almost all pet rats normally have. When a pet rat's immune system is weakened, either due to stress or from another disease, this bacteria causes upper respiratory disease in rats and when left untreated turns into pneumonia. Streptococcus, Bordatella (the same bacteria that gives your dog a cough), Pasteurella and other types of bacteria can also play a role in the severity of disease but Mycoplasma is typically the primary reason for illness.
Treatment for Mycoplasmosis is not a cure. There is no cure for Mycoplasma at this time. Treating the symptoms of the disease is all you can do to keep your rat comfortable and slow disease progression (it will eventually turn into pneumonia). Antibiotics and other medications will be prescribed by your vet based on the severity of the disease.
It is also important to note that Mycoplasmosis is very contagious. It can be shed to other pet rats very easily, therefore if you have other rats in your household your infected rat should be kept quarantined from the others and you should thoroughly wash your hand after handling him, his food, water bottle, changing bedding, or touching anything having to do with him. I know this may upset some of your other rats but the risk of the others contracting Mycoplasma is too high to keep them all together.
New treatment techniques are slowly surfacing so your vet may choose to try something new with your permission, or perhaps one day a vaccine or cure will be found. Until then, rats can still live for several months after being diagnosed with Mycoplasmosis and maintain a decent quality of life while on chronic medications.
While this bacteria can be found in rats with Mycoplasmosis and pneumonia, Streptococcus is seen more often in young rats. It is seen under the microscope as gram-positive diplococci (two tiny purple circles) and is treated with antibiotics. Treatment should be started immediately since it can quickly progress into pneumonia. Rats often die with Streptococcus infections but you have a chance if you can start antibiotics before your pet rat gets pneumonia.
If your rat seems lethargic, has excessive porphyrin tearing (from stress), isn't eating as much, or has any discharge from his nose he should be brought to the vet as soon as possible. He will not just get better on his own and waiting to see if he does usually make things worse and harder to treat.
Dusty bedding, dirty bedding, and cedar shavings bedding are the main culprits for respiratory disease when cage substrate is to blame. It would behoove you to make sure you don't use cedar shavings, the bedding stays clean, or a dusty brand of bedding. Too much dust can cause respiratory issues, as does dirt bedding where mold might start to be growing (it doesn't take long!). Cedar bedding has long been known to irritate the respiratory tract (even for humans who work in cedar mills), and even causes liver damage. Therefore it should always be avoided in pet rodents!
Colds and Pneumonia
Rats can also get sick from getting a chill from being too close to an air conditioning vent, window or door. This can give them respiratory issues and even turn into pneumonia if left untreated. Upper respiratory tract infections often turn into lower respiratory tract infections and should be taken very seriously. The breathing problems may not be due to a bacteria like Streptococcus or Mycoplasma but they should still be addressed as soon as possible.
Rats often get tumors, especially along their mammary chains. Both male and female rats are susceptible to breast tumors and these tumors can spread throughout the body, including the lungs - causing breathing problems. A radiograph (x-ray) or CT scan are the best ways to tell if your rat has tumors in his lungs.
If your rat is having problems breathing, whether or not there is nasal or ocular discharge, you should seek help from your exotics vet and start treatment as soon as possible. Even if your rat is diagnosed with an incurable disease like Mycoplasmosis, with the quick treatment he can still live a better life than if not treated.