A zoo keeper has undergone emergency surgery in hospital being "grabbed" by a big cat at a zoo in southern Queensland.

Emergency services were called to Darling Downs Zoo in Pilton, south of Toowoomba, this morning after the woman was attacked in an enclosure by one of the big cats.

The zoo said the woman, who emergency services say was in her 50s, was watching other keepers in the area home to its carnivores as usual, when she was attacked.

The zoo didn't say which animal attacked her but it is home to lions, cheetahs and a tiger, according to its website.

"This is something that she has done many, many times over the past 20 years," the zoo said on Facebook.

"She is well versed in safety protocols around potentially dangerous animals.

"Inexplicably, at this stage, one animal grabbed her by one arm and caused severe damage to it,"

The zoo added the victim was not one of the family-run zoo's immediate family.

It also said the animal had not recently had cubs.

Queensland Ambulance confirmed the woman had suffered a "significant arm injury" following an animal bite.

She has been taken by rescue helicopter to Princess Alexandra Hospital in a stable condition.

The zoo said it would be closed all day.

Workplace Health and Safety Queensland said they have been notified.

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