Parotid Tumor

So I was horrified to find this giant tumor on this horse that I’m taking care of while they are on vacation. I thought it might be Grass Glands, but it is very hard, like a rock. I was able to get in touch with the owner, and she says that it is melanoma.

Have they made any strides with immunology or other treatment? She says that the vets didn’t want to remove it because of the location. She has others in her mouth and on her anus, but smaller.

The left side of her neck also looks swollen, but it may be normal for her. The left side is soft.