It is thought Tira had been suffering from FIP for some time
Tira, the six-year-old mother of a baby Bengal tiger born at Noah's Ark Zoo Farm in Wraxhall, has died after suffering a long illness.
Keepers think she had feline infectious peritonitis (FIP), which caused multiple organ failure.
It is believed Tira had the disease since her arrival at the zoo in June and it is not yet known if she has passed it on to her new cub.
Tira rejected the surviving cub, which zoo staff are hand-rearing.
"Tira's body was severely affected by the virus," said zoo owner Anthony Bush.
"In pet cats FIP often goes undetected until the end stages of the disease as symptoms are not always very obvious.
"Suddenly the abdomen becomes noticeably swollen and the cat quickly becomes very poorly. Sadly, this appears to be what happened to Tira too."
Mr Bush said it was touch-and-go whether the cub would survive, and Tira's illness may be why he was rejected by his mother in the first place.
Tiger cub born at zoo in Wraxhall
Tira also gave birth to two other cubs - both still born - on 29 July 2009.
"Some of the signs of the disease are very non-specific, such as distension of the abdomen, lethargy and a lack of appetite," added Mr Bush.
"Of course, given Tira was pregnant when she arrived, her distended abdomen and sleepiness were to be expected.
"Understandably keepers at the zoo are devastated after spending the last few weeks working hard alongside vets to make her better, not realising that they were fighting a losing battle.
"When you work that closely with animals it's like losing a close friend and we are all feeling the loss."
Mr Bush added, sadly, that it was "always your favourite animals that die".