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Ask Dr. Michael Salkin Your Own Question
Dr. Michael Salkin
Dr. Michael Salkin, Veterinarian
Category: Veterinary
Satisfied Customers: 28450
Experience:  University of California at Davis graduate veterinarian with 45 years of experience
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Our 13-year-old female cat has developed subcutaneous tumors

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Our 13-year-old female cat has developed subcutaneous tumors on her side just behind her left forepaw. She developed similar tumors in the same general region several months ago, and we had them removed (twice) by a local veterinarian. Both tumors were fibrosarcomas. However, our cat found the experience of being taken to the vet in a transport cage, having surgery done to remove the tumors, and the recovery from the surgeries to be very traumatic. Also, the veterinarian said there was no guarantee she could ever completely remove the tumor cells using surgery. Accordingly, we wonder if there might be a way of destroying such tumors without resorting to surgery. For example, are there any agents that could be injected directly into a subcu. tumor to kill it? Incidentally, the cat is not showing any obvious signs of distress from the tumors, but they are growing.

I have had a considerable amount of experience doing surgery on small animals (mostly lab rats and mice, and a few rabbits) as I am a physiologist and I taught human and animal physiology and anatomy at U.C. Berkeley for some 35 years. I also have done research on cancer in lab animals. However, I retired in 2002, and so I have not kept up with the literature on cancer therapies.

If you have information on this question, or if you can refer me to people who might know of such solutions, I would greatly appreciate hearing from you.


Charles S. Nicoll, Ph.D.,
Professor Emeritus,
Dep't. of Integrative Biology,
U. C. Berkeley
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Dr. Nicoll, local agents haven't entered our armamentarium for addressing fibrosarcomas in cats. The FSA seen in older cats are not associated with the feline sarcoma virus and occurs most commonly on the trunk, distal limbs (as you've reported), and pinnae. Most FSA demonstrate rapid, infiltrative growth, with metastasis (regional lymph nodes, lung) occurring in less than 20% of cases. Unfortunately, metastasis has occurred in your cat - at least locally.

The clinical management of choice for FSA remains wide surgical excision, and given its relatively low metastatic rate - at least to distant sites - complete resection of fibrosarcomas would be expected to provide prolonged tumor control durations. In patients where complete surgical resection is not anatomically feasible, such as when tumors involve the distal extremities, amputation of the affected limb is usually curative. The institution of adjuvant radiation therapy may be effective for preventing local disease recurrence in dogs but we don't have enough information on that therapy in cats to routinely recommend it. In a study of 44 cats with FSA it was found that the mitotic index and tumor site correlated with prognosis, whereas histologic appearance, tumor size, and duration of tumor growth did not. Cats with FSA of the head, back, or limbs and with a mitotic index of 6 or greater had the poorest prognosis.

Please note that it becomes moot to consider injecting a tumor when we know that the FSA has already sent out streams of malignant cells from those tumors. Please respond with further questions or concerns if you wish.
Dr. Michael Salkin and 2 other Veterinary Specialists are ready to help you
Thank you for your kind accept. I appreciate it. I'll speak to you soon.

I'm going to check back with you in a few weeks for an update. Feel free to return to our conversation - even after rating - prior to my contacting you if you wish.

Please disregard the info request.