The 150kg Aldabra tortoises, Mike and Biggy, have travelled more than 200 miles by ferry and road for specialist CT scans.
A specialist team transported the pair to the Royal Veterinary College in Hertfordshire, one of just two places in the UK with a CT scanner large enough to accommodate animals of their size.
Mike, aged 27, underwent a CT scan to investigate a front leg lameness that had proved difficult to diagnose.
Biggy, believed to be more than 80 years old, underwent a CT scan as part of investigations into a lump near the base of his tail.
Mike has been diagnosed with osteoarthritis in his right shoulder, meaning the team can finally put a targeted treatment plan in place, while specialists are still assessing Biggy's scan.
Senior Veterinary Officer at Jersey Zoo, Violaine Colon, said:
"When an animal needs specialist care, we'll do everything we can to make it happen. Getting Mike and Biggy to the Royal Veterinary College was a significant undertaking, but it has given us invaluable information about their health.
"While Aldabra giant tortoises have been scanned before, facilities able to scan animals of this size remain rare.
"As part of the European Endangered Species Programme, the knowledge we gain from cases like these helps improve the veterinary care and husbandry of Aldabra giant tortoises across Europe."
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