Bear is approaching 1 year of battling ostheo sarcoma. Despite some ups and downs, he is a very happy pup. After going 7 months without a reoccurrence, a tumor developed in the muscle of his amputation site. He was originally treated with Carboplatin. When the new tumor developed, it was treated with Doxorubicin and it tripled in size in 3 weeks. I insisted on going back on the Carboplantin and after one treatment the tumor shrank enough to remove it. On the day of surgery, a chest x-ray showed a tiny lung met and they refused to do the surgery. A change in chemo drugs was suggested and Bear started on Palladia on 1/7. The tumors have not grown. Now here is the weird part. His mouth (gums and roof of his mouth) are normally black. I noticed that the pigment has started turning pink. It appears the corners of his eyes are starting to change to pink too. Has anyone ever heard of this??? All of his blood tests are normal. He has had gastrointestinal upset from the Palladia, but both of my vets are not concerned because the color is pink. They both indicated it has never been reported. I even asked if it could be a result of the combination of drugs he takes (Palladia, Tramadol, Flagyl, Duramaxx). They have no answers.