My Boxer just had surgery...?

My 9 yr old Boxer Mazie was diagnosed with mammary tumors that are cancerous. She has to have a few more removed. For now the Vet removed just one to biopsy. She told me that she had to cut into muscle to get it all out. I do understand she is in pain. It has been 5 days and the panting and shivering have not stopped. Being a boxer she is already nervous. Not so much hyper, just anxious a lot.

Have you experienced any surgeries with your dog? How long did it take to recover? How long did the panting and shaking last? She was x-rayed and scanned on Friday. She was clean and clear of any other infections or cancer. Just wondering what others' have experienced. She is also eating and drinking. I know that is a good sign.