Spindle Cell Tumors

Spindle cell tumors are cancerous growths that form under a dog’s skin. A spindle cell tumor generally shows up in dogs as they age. According to Fetchdog.com, an informational website about dogs maintained by dog experts, about 7 percent of all tumors found in dogs are diagnosed as spindle cell. For some dogs, spindle cell tumors are a normal sign of aging, but for others with more aggressive forms of the cancer, more extensive medical treatment may be required.

Occurrence

Although spindle cell tumors occur in all types of dog breeds, they’re more common in large-breed dogs. Tumors generally begin to appear in dogs that are middle age or older. On average, dogs with spindle cell tumors are 10 years old. However, more aggressive tumors known as fibrosarcoma have been found in dogs as young as 1 year old.

Symptoms

A spindle cell tumor consists of a tissue mass, or lump, underneath a dog’s skin. They’re usually located on the dog’s legs and/or between his joints. When tumors become irritated, they swell and bleed. It’s possible for the tumor to become infected. In addition, the dog’s mobility may become impaired when tumors grow near the joint area.

Cause

Fetchdog.com reports the exact cause of spindle cell tumors is unknown. As of 2010, little research has been conducted on the cancer’s origin. This type of canine cancer usually results from several changes occurring in the dog’s body all at once, triggering abnormal cells to divide and spread.

Diagnosis

A veterinarian conducts a biopsy of the tumor by removing some of its cells or the entire lump and then sending the sample to a lab for evaluation. The tumor is given a grade based on the number of divided cells it contains. Tumors given lower grades generally have a better prognosis as fewer cancerous cells have divided and spread. Cells that have divided quickly indicate a more aggressive form of cancer.

Treatment

Treatment generally consists of surgically removing the tumor and surrounding tissue. In more severe cases, the entire limb bearing the tumor may need to be removed. Vet2thePet.com, a veterinary medicine information website, indicates that tumors have shown sensitivity to radiation therapy, but they don’t react well to chemotherapy.

A low-grade tumor with a good prognosis that doesn't appear to cause discomfort in a dog may only require constant monitoring for changes to the tumor’s size that would warrant further evaluation by a veterinarian. Although the cancer won’t disappear with time, the dog’s own immune system may kill some of the cancer cells and contain it from spreading.

References

• Fetchdog: Spindle Cell Tumors and Fibrosarcoma in Dogs
• Vet 2 the Pet: What Is a Spindle Cell Tumor?