swollen rooster tubercle

[aculaurel]

The vet says he has a tumor in his urine sac. He doesn't have abscesses. It's just thick urine looking like pus. He took tissue samples and said it appears to be cancer. He said further that 90% of cancer like this is due to Marek's. I don't know that it is. None of my other 8 chickens has shown any signs of illness. If he had had Marek's long enough to cause cancer, you'd think one of the other chickens would have symptoms by now.

I'd appreciate any thoughts on this. I'm heartbroken about my sweet roo.