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Ask Dr. Michael Salkin Your Own Question
Dr. Michael Salkin
Dr. Michael Salkin, Veterinarian
Category: Dog
Satisfied Customers: 30360
Experience:  University of California at Davis graduate veterinarian with 45 years of experience
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My dog has osteosarcoma and had his leg removed about 6 weeks

Customer Question

My dog has osteosarcoma and had his leg removed about 6 weeks ago. He'd had the tumor for 6 months before it was diagnosed, it was very small. When he was diagnosed they said he had two months to live. I did not have his leg removed at that time and opted for pain medication. We went for 10 months with the tumor getting bigger and bigger until early June I had a complete check up of him with blood tests and scans to see if he had tumors any where else. He was perfect except for the huge tumor on his leg. The doctors thought that he might possibly have some other kind of cancer since it had been 15 months since he first started limping and now he had this huge tumor on his leg. I decided to remove the leg hoping that would solve the problem. He's 13 and I had his leg removed. The biopsy showed that he did have osteosarcoma but that it hadn't spread up to that point. Now 6 weeks after the surgery he is panting again. I'm afraid the cancer has now gone to his lungs. I believe when you operate for cancer it causes it to spread. The tumor was totally localized in one spot for 15 months without spreading. Now he has started panting again which was a behavioral thing when he had the leg tumor. It's been such a short time since the leg was removed and he was clean at that time. Could the cancer have spread to his lungs that quickly when he had no tumors what so ever right before the surgery?
Submitted: 2 years ago.
Category: Dog
Expert:  Dr. Michael Salkin replied 2 years ago.

Aloha! You're speaking with Dr. Michael Salkin I believe that there are misconceptions that need to be addressed. It's unreasonable to assume that an osteosarcoma wouldn't have metastasized while that tumor was growing to such a size. We assume that 100% of these tumors have already metastasized at the time of initial diagnosis. It's important to recognize that X-rays can't detect micro metastasis below a certain size - usually 2 mm - below which point either CT or MRI is required for detection. A biopsy can't determine that a cancer hasn't spread. Advanced imaging is required. If a cancer is disturbed during surgery, yes, cells can shower into the surrounding tissues and enter the bloodstream, thus seeding other areas. The lungfields are the primary distant metastatic site for osteosarcoma. When an amputation is performed, however, unless malignant cells were already present at the amputation site - and that's likely in Winston's case - we don't expect the primary cancer site to be disturbed. To answer you directly, yes, cancer could have spread in just 6 weeks to his lungs. In fact, the standard of care is to recheck lung films in just 4 weeks if we're not sure if we're seeing metastatic lesion in the lungs upon initial X-rays. I don't believe, however, that "he had no tumors whatsoever right before surgery". Please respond with further questions or concerns if you wish.

Customer: replied 2 years ago.

He wasn't just x rayed, he had either a cat scan or an MRI before his leg was removed. I can't remember which but this treatment was done in one of the biggest and most sophisticated animal hospitals in NYC. There are two. One is the Animal Medical Center and the other is Blue Pearl an animal specialist hospital. He had been treated at Blue Pearl before. He had no tumors. The doctors actually changed their minds about the sarcoma when the tests came in. I had never however allowed them to aspirate the tumor so they had to go by the x rays from the first visit and the scans done in the complete examination when the tumor was so large.

Expert:  Dr. Michael Salkin replied 2 years ago.
Those are wonderful hospitals. Thank you for the additional information. It's best to repeat Winston's chest films at this time. I fear that you're going to have a difficult decision to make.
Please continue our conversation if you wish.