Vets were called last week to see Princess, the nearly nine-year-old Bengal tiger, after her keepers saw a sudden change in usual behavioural activities.
The veterinary team attended, where they successfully took bloods for analysis, after finding no other signs to indicate concern.
The results from the bloods were returned over the weekend but unfortunately the sanctuary's vets concurred that the kindest thing for her would be to put her to sleep.
Steve Nichols, CEO of the Park, said “It has been a long weekend coming to terms with the outcome,
"Princess came to us in 2016 and has always been such a loveable character. She will be sorely missed by the
keepers and wider zoo family, including our dedicated fans and visitors."
The park has seen an outpouring of support during the week after the sad news.
“We’ve had hundreds of messages from our visitors and each one is thoroughly appreciated," Steve commented.
As a regular star of the park's live videos on social media due to her huge personality, hundreds took to social media to express their sadness.
Amongst them, Alison Hall said: "So sorry to here this. RIP princess
"We were lucky enough to see her on our tiger tour so beautiful."
Rachel Mercer said: "I am so sorry for the loss of Princess My thoughts go out to not only Steve but all of the keepers involved.
"She was a beautiful Tiger who i got to meet and get up close and personal with during my tiger feeding experience. A day that will never be forgotten. May she rest in peace."
Hayley Chilvers said: "So sorry to hear this sad news Steve, and so glad I got up close on my experience just a few months ago (even if she was more interested in Sleeping).
"RIP beautiful Girl, you and you’re team do an amazing job and she was very lucky to be loved by you all."