The Rat Fan Club

Below are pictures of surgically removed rat mammary tumors. WARNING: Some of the pictures are quite graphic.

This is Diamond, who had a large benign mammary tumor, before and after surgery to remove the tumor.

Another large benign mammary tumor. The picture is a bit dark, and the tumor was actually a lighter pink color.

This picture shows a benign mammary tumor containing numerous pockets of what I assume is milk. These can be seen in the photo as the white areas. These pockets of a thick white or yellowish liquid are quite commonly found in benign mammary tumors removed from rats. The liquid is distinct from pus and has no bad odor.

Here is a series of pictures taken during surgery to remove a small mammary tumor from Princess. The first view shows the tumor showing through the skin after the fur has been shaved. Because one portion of the tumor appears dark, it is likely that at least that part of the tumor is malignant. During this surgery, Princess was also spayed, and you can see the incision for the spay on her abdomen. In the second picture, the dark part of the tumor can be seen on the right side of the tumor.

Here is Princess after both incisions are stapled closed. There was almost no bleeding where the spay was done, but the malignant tumor bled some. The fourth picture shows the removed tumor. The right half of the tumor appears as a typical benign mammary tumor, white to pink in color, but the dark area on the left side is no doubt cancerous. In rats, cancerous mammary tumors almost always appear dark like this because they have a much greater blood supply, and also commonly have pockets filled with dark red bloody fluid.

Here is a large benign mammary tumor, complicated by mammary cancer next to it, which had compromised the skin over the benign tumor. I treated Jewel with tamoxifen for the mammary cancer successfully for almost a year. For a photo diary of Jewel’s cancer, click here.

This tumor was 4 inches long and weighed 190 g. The rat with the tumor weighed 537 g, and after the tumor was removed, Honey weighed 348 g.

With such a large tumor, some of the excess skin must be removed. On top of the removed tumor is a piece of the skin that was removed along with the tumor. Honey was in good condition and recovered well from her surgery.

This is the worst benign mammary tumor I have ever seen. The tumor had outgrown its blood supply and was dying and turning necrotic, indicated by the dead black skin over it. This tumor was 10 cm across, about 4 inches, which is smaller than the tumor above, but the rat was in much worse shape. The poor rat was very emaciated, and died a few hours after the surgery.

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