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Myxosarcoma reoccurence

22 10:16:53

Question
Dana,
We have a 7yr old Flemish Giant neutered male that is a house rabbit. He was diagnosed in June with a subcutaneous Myxosarcoma near the right hind leg that was removed with good clean margins and was well encapsulated. There was some blood supply. Unfortunately, this growth has reoccurred in the same spot and is approximately the same size as before. The vets are rabbit-savy and have referred him to an Oncology specialist next week. Chest x-rays taken last week were clear. He is in otherwise good health. Do you have any advice?
Thanks!

Answer
Dear Chad,

Myxosarcoma is a malignant form of soft tissue sarcoma.  It can be locally very invasive, but has a low to moderate likelihood of metastasis to other areas (particularly the lungs).  For this reason, most vets opt to treat this surgically in rabbits, since radiation therapy is not well "calibrated" for rabbits yet.

We've had rabbits with recurrent sarcomas, and the only treatment our vets recommended was surgical removal each time the lesion reappeared.  It worked pretty well.

I have to wonder whether anyone has considered trying the drugs that block angiogenesis to treat this type of tumor, but I don't know of anyone who has done so in rabbits.  You might ask your vet if s/he is on any of the large veterinary listserves (particularly for exotics) to see if anyone has further treatment options than surgery for this type of cancer in a rabbit.

I wish I could offer you more suggestions, but rabbit medicine in this area is pretty much still in its infancy.  I hope your bunny will have this removed again, and this time it will not recur.

Good luck,

Dana