Yesterday's health check saw our faces drop as we turned Willow over onto his back on the surgery table. Not visible when he was joyfully tearing around in his enclosure the day before, now we were looking at all the evidence of liver cancer, as an ominous swelling appeared where his right liver lobe would be. Suspicion had been mounting in previous weeks as it appeared that Willow was losing weight and had a dull-looking coat. Nothing more indicated that anything was wrong – certainly not in his demeanour, which saw him bombing through the grass with his friends, enjoying giddy games of play and clearly unperturbed by and ignorant of the growth that was killing him inside.

Lying there, small and vulnerable on the surgery table Willow was now in everyone's prayers. As vets Heather and Lara scrubbed up, the sad faces and still hush in the room said it all. A few minutes later, Heather had opened Willow's abdomen enough for us all to see what we had feared. A huge mass of cancer on his right liver lobe, literally draining the life blood of this beautiful bear away.

With every other bear we've seen in similar circumstances there has been no option but to say a tearful goodbye and euthanasia, knowing that the cancer has been impossible cut out.

Turning away with a breaking heart to call Willow's sponsor, suddenly I heard Heather saying this cancer might be possible to remove. For the next few minutes she and Lara went through every option until finally confirming that yes, they'd like to try. After all, what did we have to lose? We could gently put him to sleep there and then, or try – and if all failed, well, he would still be finally and so sadly euthanised there on the surgery table.

For the next few hours I had nothing but deep, deep admiration for our team – vets and nurses together worked quietly, urgently, methodically on Willow, while the rest of us willed him to live.

At last the tumour was out – to gasps of disbelief – as the weigh scales topped 4.3kgs. Like something out of a horror movie, with a life of its own, this cancer was another example of so many we've seen before and yet more proof – if any was needed – of just how and why bear farming is killing China's majestic species of Moon Bear.

For Willow (pictured below in the barbaric cage he was kept in for 10 years), the minutes tick by as he slowly recovers enough to take his medicated fruity shake, and fate takes over. This was major surgery on a sick and depleted bear and we are under no illusion that he is out of the woods yet. If praying saves lives, Willow will be back bouncing through that grass with his chums – a miracle bear who beat all the odds.

But for now, we just wait.