Pet rats are more loveable than many people would think and anyone who has one knows this. Some of the best things about rats is that they develop such unique personalities and are incredibly smart (how smart?). But quite possibly the worst part about having a pet rat isn't, the long, hairless tail or the beady eyes, it's the super short lifespan - one that is unfortunately often cut even shorter due to tumors.
Kinds of Tumors
Rats, like other exotic pets, can get many different kinds of tumors in and on their bodies. Some grow quickly and are very obvious while others are more hidden and go unnoticed until your rat starts acting differently.
Mammary Tumors - These tumors can be benign or malignant (cancerous and non-cancerous) and grow in the breast tissue of both male and female rats (yes, boys have breast tissue!). They can be very fast growing and large, sometimes encompassing an entire side of a rat. If they start to seep fluid it is usually a creamy, milky consistency, or very chunky with a tinge of blood. These can be surgically removed by your exotics vet but since it can be very hard to completely excise all of the affected breast tissue regrowth is common. Spaying or neutering your pet rat may help reduce the likelihood of your rat getting breast tumors (usually fibroadenomas) but there are no guarantees.
Lipomas - Also known as a fatty tumor, these growths are exactly what their name implies - fat. Many species of animals get lipomas (and so do people!) and there isn't any way you can prevent these tumors from popping up on your pet rat. These are non-cancerous growths but can grow very large and make it difficult for your rat to move around. These tumors are usually removed when your rat is having a problem getting about.
Cysts - Male rats are most prone to this kind of growth. A cyst is a fluid filled sac and not actually a tumor (unless it is a cystadenoma) and can be found on the inside or outside of your rat. Males will often get cysts on their back where their sebaceous glands are extra active but females can get ovarian cysts and cysts can pop up just from a bad skin infection. They are usually lanced or popped by your vet and the fluid, or thick secretion, is squeezed out. They can reoccur unless surgically removed but they don't usually cause a major issue unless they become infected.
Brain Tumors - These tumors cause neurologic symptoms and may or may not be able to be seen on your rat since the skull usually hides them. Unfortunately brain tumors are inoperable and rats should be euthanized if their quality of life is compromised by one.
Other kinds of tumors of course exist but aren't as commonly seen in rats as the aforementioned types. Fibrosaracomas, fibromas, and squamous cell carcinomas can all be difficult to completely excise (remove) and grow very quickly on different parts of the body including the face.
Not all vets treat exotic pets and not all exotic vets will operate on a rat. If your rat needs surgery be sure to find an experienced exotics vet that you feel comfortable working with - and ask for the tumor to be sent for a histopathology (biopsy) review to know exactly what kind of tumor your rat had removed.