Pet Rats and Tumors

As pets, rats can be a great alternative to owning dogs or cats. However, they are not without their own set of health problems, one of the most common of which is tumors.

Before we start talking about the different types of tumors seen in rats, let’s start with a bit of background information on tumor growth and development. Tumors are classified as being benign or malignant; benign tumors are considered to be non-invasive and generally harmless to the animal, while malignant tumors are associated with aggressive disease and cancerous spread to other organs. In terms of their potential to be removed from the body, benign tumors are typically encapsulated and separate from the surrounding tissues, which means that they can often be surgically removed without complication. In contrast, malignant tumors are usually embedded in the surrounding tissues and organs, making removal difficult. The concern with benign tumors is due to the fact that a) they can grow so large that they can interfere with the animal’s normal movements, and b) they require nutrients in order to survive. They get these nutrients from the animal’s diet, and as a result, the animal can become sick from a lack of adequate nutrition. The good news is that the majority of tumors in rats are benign, which means that surgical removal is usually an option.

The most common type of tumor in rats is a mammary tumor (also called a benign mammary fibroadenoma). The term “mammary” can be a little bit confusing, because while a large percentage of these tumors are found in the groin region, they can also be found growing all the way from the hind legs to the armpits. This type of tumor is found in both male and female rats, although they are much more common in females.  As mentioned earlier, the concern with benign tumors is that if they are not removed, they will continue to grow – it is possible for a small peanut-sized tumor to grow to be the size of the rat itself, which can become a huge problem in terms of the rat’s ability to move around. A tumor that size might also start to drag along the bottom or sides of the cage, and that continued friction can create an open wound on the outside of the tumor.

There are several options when it comes to dealing with these types of tumors:
1. Spay or neuter your rat. While the thought of having this operation performed on something as small as a pocket pet may seem a little unnecessary, there have been several studies that have shown that spaying or neutering (and thus removing the reproductive organs) can have an effect on tumor growth because it removes the hormones that can contribute to tumor development.
2. Feed your rat an appropriate, well-balanced diet. Similar to humans, nutrition in rats can play a role in cancer development. While some of this information is still anecdotal, feeding your rat a proper, well-balanced diet that is high in protein and low in fat is always a good idea, not only because it may prevent tumor growth, but also because it improves the overall health of your pet.
3. While playing with your rat, take the time to carefully run your hands over its body, checking for lumps or bumps. If caught early, these lumps can be surgically removed by your veterinarian. The smaller the lump, the easier it will be to be removed, but keep in mind that any kind of removal surgery involves putting your rat under general anesthetic, which is always associated with some degree of risk (this is something your veterinarian should go over with you prior to surgery).

Unfortunately, removing the tumor doesn’t guarantee that another tumor won’t develop later on, but it may improve the quality of life for your pet in the meantime. Another potential advantage with surgery is that once the tumor is removed, your veterinarian can have it sent for pathology in order to determine if it is malignant. This is an added cost, but it may be an option if you are considering the future quality of life for your rat, should another tumor develop later on.

The second type of tumor is a pituitary adenoma (tumor of the brain). These seem to be more common in females as well, although there have been some reported in males. Rats with this type of tumor will often have neurological signs because the tumor is growing and pushing down on the brain; these signs may include a head tilt and depression. Unfortunately, removal of this type of tumor is not really an option, so often the most humane option is euthanasia.

Tumors in rats are an unfortunate reality that comes with owning these animals, but early detection and proper care can help make them a lot more manageable for both you and your pet.

By Kyla Townsend – Pets.ca writer