It's a lot easier to explain cancer in animals when people can see the actual tumor(s). For cancers that are only inside the body, it's more difficult for people to understand what is actually happening and why their animal is so sick. Yes, I can show them x-rays or ultrasound images, but it's just not the same as really seeing what it looks like. So, here's what it looks like...and why you often can't just "cut it out."
These are necropsy pictures from a dog that had kidney cancer that had metastasized to almost every organ of his body.
This first picture is one of his kidneys that's been cut in half. Both kidneys looked like this and were totally non-functioning. All that whitish-pink lumpy stuff is cancer.
This one is his bladder. The bumps on the bladder are metastases...little mini-tumors that spread from the main one. I didn't get a picture, but he even had metastases on his ureters.
This is his stomach. More bumps, more metastases...
and this is his liver...
and finally, his heart...it's harder to see the bumps on his heart, but the main one is just below the fat (yellow stuff near my fingers).
Every organ I looked at had metastases, the gall bladder, the adrenal glands, the entire intestinal tract, the diaphragm, the lungs, you name it. Bad disease. There was no saving this dog.