By Dr. John De Jong / Ask the Vet | Sunday, July 29, 2012 | http://www.bostonherald.com | Lifestyle

Dear Dr. John,

Frustration and fear are the reasons I write to you today regarding my 9-year-old Lhasa apso dog. Polo has led a pretty healthy life until just over a year ago when he developed lameness on his left front leg. We started to notice a swelling that was hard and firm. We took him to see the doctor who took X-rays and informed us it appeared that he had a mass (a nerve sheath tumor) that did not seem to involve the bone, and that surgical removal would be in order. We immediately scheduled the surgery and had the growth biopsied. Polo healed well and had months with no problems. After about eight months, we noticed a growth popping up again. We were warned that it could happen — but so quickly? Another surgery was done. Here we are six months later and he has another really large swelling and cannot really use the foot. What should we do? We are told the growth might not be easily removed and that amputation may be needed. We love our dog and want to do what’s best.

— W.Q.

Dear W.Q.,

The problem that Polo is facing is not all that uncommon. Nerve sheath tumors form from Schwann cells which produce myelin. Myelin is similar to an insulation that surrounds the long part of nerves known as axons. These tumors can be benign or malignant just like any other tumor. Only a biopsy can determine what degree of malignancy might be involved. Some speculate that these tumors arise in locations of previous injury. Presentation may involve what you noticed with lameness or pain, but usually the swelling is the tip-off. Your veterinarian did what I would have done with X-rays and attempting to spare the leg with local dissection trying to excise the tumor. The problem is that these kinds of tumors often have multiple fibers extending in many directions and it is almost impossible to remove all, thereby leading to recurrence. The median survival time for dogs with these tumors is about two years; despite that fact, I would suggest you consider amputation. You, your veterinarian and Polo have given best efforts, but I think the possibility of debulking again may be exhausted. Good luck!

John de Jong, D.V.M., is owner/operator of Boston Mobile Veterinary Clinic and partner/chief of staff at Neponset Animal Hospital.

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