Sampson, our 11 ½ year old Rottweiler was diagnosed 4 weeks ago with osteosarcoma of his right proximal humerus. He had a right, front leg amputation 2 weeks ago.  There were no signs of metastasis on radiographs and his lymph nodes were negative.  He has been taking rimadyl 100mg BID for osteoarthritis and his hypothyroidism has been well managed on 0.6mg of soloxine. He has had a mildly elevated alkaline phosphatase ( ~300 U/L for several years).We had always thought it was due to non-specific liver inflammation or continued use of  rimadyl. During his wellness exam two months prior to diagnosis in February 2010, his alkaline phoshatase was 541.  I assume due to the osteosarcoma.  Four weeks post amputation, the alk phosphatase has risen to ~700.  I thought is would have improved post surgery or remained the same. He has been on multiple medications since his amputation and prior to bloodwork (tramadol 50mg, rimadyl 100mg BID, Tylenol with codeine for a short amount of time, amantadine 100mg for several days, amoxicillin 500mg, transdermal skin patch for pain).  Also I am unclear if the alk phospatase can be eleveated from residual anesthesia.  I am aware of the data of poor prognosis and elevated alkaline phosphatase. Is this a potential indicator of micrometastasis or multiple medications metabolized in the liver?

Renee