Bella, a critically ill mum at the rescue centre, had to be put down after a mass in her abdomen was found to be an aggressive cancerous tumour.
There was no treatment available and Bella was put down on the advice of a vet.
-> Heartbroken owner's vigil for missing puppy as fears of Yorkshire dog snatching ring continueThe good news is that Bella's litter of kittens are very healthy and one of them has already been adopted.
A spokesman for the centre said: "We're very sad to have to tell you all that Bella, our critically ill mum was put to sleep today after the mass in her abdomen was found to be an aggressive, necrotic, cancerous tumor which there was simply no treatment for.
"Bella had perked up significantly and was comfortable and had lots of cuddles at the vets but we chose not to wake her up from her anaesthetic.
"A very sad day but she is now at peace which was the last thing we could do for her.
"On a happier note, her kittens pictured are doing well and the kitten that came in with her from her previous litter was neutered yesterday and went home with one of our vets who fell in love with him and adopted him."
A spokesman for the non-profit rescue centre told the Yorkshire Evening Post that the centre has a 'no kill policy' and that rescue cats are never put to sleep unless a vet decides that it's in the cat's best interests for health reasons, as happened with Bella.
-> Met Office issues yellow weather warning for Leeds as icy conditions set to hitTo adopt a cat go to www.leedscatrescue.btck.co.uk