Jax's surgery

A mass recently grew on our dog Jax's body. It went undetected for some time as he was living with my parents instead of with me since I live in an apartment. The mass ended up getting cut open and then infected.  We got him treated but they were only able to clean/treat it and give him medicine. I was told the mass needs to be removed after the wound heals. I would truly appreciate any help that is given. 

Please and thank you.