A critically endangered monkey has given birth just months after pioneering surgery saved her from undergoing an amputation.

Masaya, a 15-year-old roloway monkey at Chester Zoo, had a golf-ball-sized mass removed from her foot last summer in a complex operation carried out jointly by zoo vets and surgeons from the University of Liverpool's Small Animal Teaching Hospital.

Despite finding no previous examples of the procedure on roloway monkeys, the team successfully conducted surgery to save all but one of her toes.

Now, she has given birth to little Lagertha, who primate experts at the zoo say is already showing signs of her mother's spirit.

"Masaya is a very experienced mum and she's parenting magnificently," said Zoe Edwards, primate keeper at Chester Zoo.

"Lagertha is only a few weeks old and is very dinky, but already curious about the roloway monkey habitat and inquisitive about us.

"The fact Masaya's foot has healed so well is a huge relief. If she'd had an amputation, we'd have been left with real questions about whether she could hold her offspring or continue with her normal behaviours."

The new arrival is Masaya's third daughter, and her birth marks a significant moment for the species.

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Zoe added: "Chester Zoo is one of only two places in the UK that roloway monkeys can be found, and Masaya is very important - not just to her family, but to her whole species. There are only a few breeding females in zoos in Europe."

According to the International Union for Conservation of Nature (IUCN), fewer than two thousand roloway monkeys live wild in Ghana and the Ivory Coast, where they face habitat loss and poaching.

They are so rare that the health of individuals like Masaya is highly significant to the European Endangered Species Programme, the breeding project set up to ensure the survival of the species.

Masaya had experienced recurring problems with her foot since she came to the zoo in 2023. Despite x-rays, ultrasounds and biopsies, vets struggled to identify the cause - eventually concluding a likely persistent abscess, possibly from an old thorn injury. When the swelling worsened in 2025, the decision was made to take Masaya to Liverpool for a CT scan.

Charlotte Bentley, Veterinary Officer at the zoo's Animal Health Centre, said: "It's not every day you take a monkey to vet school. We had to bring everything she might need, from anaesthesia equipment to medications and blankets.

"Following the scan, we decided an operation was the way forward. She's been an absolute trooper all the way through, and I'm just glad we were able to do something for her."

Rachel Burrow, vet and lecturer at the University of Liverpool, played a key role in the CT scan and the operation.

She said: "This was the last chance to save Masaya's foot before amputation. Working with primates is completely different from my usual patients, who are typically cats and dogs, and it was a real privilege to care for such a rare animal. It's great to see the surgery was a success - she's comfortable, active and using the limb well."

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Masaya and Lagertha, who is named after a Viking queen, can be seen alongside four other monkeys at Chester Zoo.

Find out more about the zoo's Animal Health Centre here.