When Luca the two-toed sloth stopped eating well, became lethargic and lost weight, the answer was not visible on an ordinary X-ray. It took a whole-body CT scan, surgery and careful laboratory work to reveal an unusual problem inside his stomach.
Luca was one of more than 120 animals taken in by Minnesota Zoo after SeaQuest closed in February 2025. According to the Minnesota Zoo Foundation, his symptoms became serious enough to require hospital care and supplemental feeding. His case is a useful reminder that sloth care is highly specialised, and that an apparently simple loss of appetite can have a complicated cause.
The mystery hiding inside Luca's stomach
The veterinary team began with regular radiographs, but those images did not explain Luca's condition. They then arranged a whole-body CT scan at a local veterinary specialty hospital. Unlike a standard radiograph, which compresses structures into a flat image, CT builds detailed cross-sectional views. That can help clinicians separate tissues and see the position and shape of an abnormality more clearly.
The scan appeared to show a tubular object obstructing Luca's stomach. Surgery delivered a surprise. It was not a swallowed foreign object, but abnormal tissue. Samples showed significant mineralisation of the stomach lining, meaning minerals had accumulated in tissue where they should not normally form a hard deposit.
Minnesota Zoo reported that the change was likely linked to an inappropriate previous diet containing too much vitamin D. That conclusion belongs to Luca's veterinary team and his individual history. It should not be turned into a rule that every mineral deposit in every sloth has the same cause.
Why mineralisation is a known concern
Luca's case is unusual, but the broader problem is documented. A veterinary pathology study of 19 managed two-toed sloths with soft-tissue mineralisation found deposits in several parts of the body. The stomach lining and kidneys were among the most commonly affected tissues.
The study also shows why diagnosis needs care. Kidney disease appeared to contribute in many animals, while other cases suggested that calcium, phosphorus or vitamin D imbalances could be involved. The researchers did not identify one universal explanation. Soft-tissue mineralisation is a finding with possible interacting causes, not a single disease that can be diagnosed from a photograph or one symptom.
For Luca, the CT scan helped locate the physical problem, but imaging was only part of the answer. Surgery allowed the team to see the tissue directly, and laboratory examination helped identify what it was. His history, diet and response to treatment added further pieces to the puzzle.
Sloth nutrition is not guesswork
Vitamin D is essential to many animals because it is involved in calcium balance and healthy tissues. The lesson from Luca's story is not that vitamin D is bad. It is that the right nutrient at the wrong level can still be harmful, especially in a species whose nutritional needs are not the same as those of people or common pets.
A pilot study of nine managed Hoffmann's two-toed sloths measured vitamin D metabolites, minerals, hormones and dietary intake. The authors described their results as a starting point for further research, not a finished feeding formula for every sloth.
Cornell University College of Veterinary Medicine has also supported research into vitamin D metabolism and calcium balance in two-toed sloths. That work connects blood measurements with diet and husbandry across zoological institutions, with the aim of improving care and reducing disorders such as soft-tissue mineralisation.
This is why responsible managed care involves zoo nutritionists, veterinarians, keepers, laboratory testing and detailed records. A diet that looks healthy to a human observer can still contain the wrong balance for a specialist animal. Changes in appetite, weight, behaviour and droppings may be small, so knowing an individual's normal pattern matters.
Recovery was slow and carefully managed
There was no dramatic overnight cure. Minnesota Zoo says Luca received intensive supportive care, dietary changes and continuing medical management. By June 2026 he had regained weight and returned to normal activity. In July he was introduced to Chewie, another sloth rescued after the SeaQuest closure, and the pair now share a habitat on the zoo's Tropics Trail.
That timeline matters. A good welfare story is not only about the moment a scanner finds something. It is also about the quieter months of feeding, monitoring, adjusting care and watching for setbacks. Recovery has to be measured in the animal's condition and behaviour, not in how quickly the story reaches a happy ending.
Why advanced imaging matters for zoo animals
Luca had to travel to an outside veterinary hospital for his CT scan. The Minnesota Zoo Foundation says the zoo's planned animal hospital will include its own CT scanner, reducing the need to transport animals for this kind of imaging. For an animal that may already be unwell, avoiding an extra journey can reduce handling and stress.
Technology does not replace experienced care. It gives the team another way to ask better questions. In Luca's case, the CT image turned a vague set of symptoms into a visible target for further investigation. Surgery, pathology, nutrition and long-term observation then completed the picture.
Luca's recovery is encouraging, but its most useful lesson is practical: specialist animals need specialist care. Careful diets, patient observation and the right diagnostic tools can reveal problems that would otherwise remain hidden.
Sources
- Minnesota Zoo Foundation: A Two-Toed Sloth's Slow and Steady Recovery
- Veterinary Pathology via PubMed: Soft Tissue Mineralization in Captive 2-Toed Sloths
- Journal of Zoo and Wildlife Medicine via PubMed: Vitamin D Status of Indoor-Housed Hoffmann's Two-Toed Sloths
- Cornell University College of Veterinary Medicine: Vitamin D Metabolism and Calcium Homeostasis Research
Featured image: Luca's CT scan, showing the mineralised tissue identified in his stomach. Credit: Minnesota Zoo Foundation.