The Animal Medical Center’s webmaster received the following electronic query: “My cat has a mass on its toe and my veterinarian has recommended amputation of the toe. Should the mass be biopsied instead?” Here is my response:

Maybe Not a Biopsy

Given how small a cat toe is, a biopsy might not be possible. Once the surgeon removes a small piece of the mass for submission to the lab, the skin over the mass needs to be sutured closed. The skin on a cat’s toe is very tight and closing up a biopsy site may not be possible in this particular location. Hence, an amputation of the toe removes the tumor and the excised tissue can be submitted for biopsy.

Maybe a Biopsy

If the biopsy site can easily be sutured closed, then a biopsy will provide a diagnosis and expected outcome and also direct future testing and treatments.

Biopsy Alternatives

Malignant tumors of the toe often destroy the toe bones. This can be seen on an x-ray. If there is evidence of bone destruction on an x-ray, then the mass is likely malignant and the toe should be amputated to give the best chance for complete tumor removal. Another method of determining whether or not the mass is malignant would involve sedating the cat and using a needle to remove a few cells from the mass. The cells can be analyzed in the laboratory and may give an indication of malignancy.

Should Any Other Testing Be Performed?

Any pet with a mass, should also have the lymph nodes in the area of the tumor evaluated by using a needle to remove a few cells from the mass and having a pathologist evaluate the cells under the microscope. In a cat with a hind toe mass, we check the lymph nodes behind the knee; in a front toe mass, we check the lymph nodes in the armpit. Because toe tumors can be malignant, a chest x-ray to check for tumor spread to the lungs should be performed in any pet with a possible tumor.
Read this cancer survivor story about a dog with toe tumors.