Assessment of urinary metanephrine and normetanephrine fractionation analyses as aids in the antemortem diagnosis of pheochromocytomas in clouded leopards (Neofelis nebulosa).

Objective: To examine the normetanephrine- and metanephrine-to-creatinine urinary fractionation ratios of clouded leopards (Neofelis nebulosa) at various ages. We hypothesized that clouded leopards with large metanephrine- and/or normetanephrine-to-creatinine fractionation ratios would have a pheochromocytoma on postmortem examination. Those subjects with comparatively smaller fractionation ratios would not have a pheochromocytoma on postmortem examination.

Methods: Clouded leopards housed at a zoological institution or sanctuary were included in this study. Patients were examined within a hospital environment. All samples were obtained from January 2020 through August 2021. Urine was collected from patients by direct free catch, cystocentesis, or urinary catheterization and analyzed for metanephrine- and normetanephrine-to-creatinine fractionation ratios. Postmortem examinations were performed on animals that died naturally or were euthanized for various comorbidities to determine if a pheochromocytoma was present.

Results: This experimental study included 1- to 16-year-old clouded leopards, 11 male and 6 female, managed under human care. The 2 clouded leopards in this study with normetanephrine- or metanephrine-to-creatinine fractionation ratios greater than 4 times the high end of the ranges identified in the subjects of this study had confirmed pheochromocytomas on postmortem examination.

Conclusions: Normetanephrine- and metanephrine-to-creatinine fractionation testing may be useful tools in the antemortem diagnosis of pheochromocytomas in clouded leopards.

Clinical Relevance: Normetanephrine- and metanephrine-to-creatinine fractionation testing may provide a minimally invasive antemortem method of screening for pheochromocytomas in clouded leopards. Quantitative studies are needed to determine if this testing is consistently able to diagnose pheochromocytoma in live clouded leopards.