Galiana More, who owns the Matroskin cat shelter which treated Crumbs, said she believed the tumours caused multiple organs to collapse.
“When this is a large set of such multi-organ failure, the body simply can not cope, despite the fact that Kroshik was really a fighter,” she said.
The official cause of death has not yet been established. A post-mortem may confirm if weight issues or the tumours ended the cat’s life.
Crumbs’s test results were normal in the final weeks of his life.
“Cats always hold on to the last, they do not show this disease,” Ms More said. “It hurts that we didn’t know about it before, couldn’t help.
“This is a great loss for us, because Kroshik was a symbol of hope for everyone, and we really wanted to publish only good news. It’s really painful to talk about it.”