A vet confirmed Skye would need specialist surgery and dedicated aftercare as the growth was diagnosed as a sarcoid, a kind of skin cancer.
His owner was unable to care for him, so he has been watched over by local grooms and volunteers.
It was initially thought that Skye should be put to sleep, but anxious volunteer Emma Norval who was helping care for him called The Donkey Sanctuary to see if they could offer any support.
The Donkey Sanctuary and World Horse Welfare worked together to explore other treatment options for Skye.
Jenna Goldby, Donkey Welfare Adviser at The Donkey Sanctuary, said: “Due to the nature of Skye’s sarcoid, the only treatment option available was to remove it via laser treatment.
"It was not going to be possible to remove it on site, so World Horse Welfare transported him to the University of Glasgow, School of Veterinary Medicine for the operation.”
John Burns, Field Officer at World Horse Welfare, said: “Because the sarcoid was on Skye’s chest the operation had to take place with him standing.
"Under the expert care of Professor David Sutton, the tumour was removed using laser treatment.
“Everyone is really hopeful that Skye will continue to make a full recovery and go on to live in very good health.”
Emma Norval said: “If it had not been for such a quick response from The Donkey Sanctuary I don’t think the lovely, gentle Skye would be here today. He is such a lovely boy.”
Jenna added: “This is a great outcome for Skye and I hope he goes on to live a happy and enriched life. The Donkey Sanctuary has a team of Donkey Welfare Advisers around the country and we’re here to offer free support and advice to donkey owners.”
Following surgery, Skye was moved to a holding base funded by The Donkey Sanctuary, where his health is continuing to improve.
He has settled in well and is receiving the care that he deserves from his dedicated grooms.