Dilated ureters, renal dysplasia, and chronic renal failure in an African elephant (Loxodonta africana)

Bilateral renal dysplasia with systemic fibrous osteodystrophy in a four-toed hedgehog (Atelerixalbiventris)

A 4-month-old female four-toed hedgehog (Atelerix albiventris) presented with lethargy, anorexia, dyspnoea and weight loss. Following death, post-mortem computed tomography (CT) and an autopsy were performed. CT revealed that the external surfaces of bones, including the cranial bones and vertebrae, were rough and osteolytic lesions were present multifocally in the ribs and some appendicular bones. On gross examination, both kidneys were severely enlarged and, on cut sections, a few cysts (up to 1 mm diameter) were present in the medulla. The cervical, thoracic and lumbar vertebrae were diffusely enlarged with deformation of the intervertebral discs. Histologically, there were immature glomeruli and tubules and adenomatoid/atypical epithelium in the kidneys. These changes were interpreted as renal dysplasia. In the bones evaluated, the trabeculae were thinner than normal, decreased in number and surrounded by many osteoclasts, with abundant fibrous connective tissue between atrophied trabeculae. These changes were consistent with fibrous osteodystrophy. Although kidney diseases are common in four-toed hedgehogs, there are no reports of congenital renal diseases, including renal dysplasia. To the best of our knowledge, this is the first report of the clinical and pathological features of renal dysplasia with fibrous osteodystrophy in a four-toed hedgehog.

HYPERCALCEMIA AND METASTATIC MINERALIZATION INVOLVING FOOTPADS IN ROCK HYRAXES (PROCAVIA CAPENSIS)

Three rock hyraxes (Procavia capensis) maintained in a zoological collection had chronic hypercalcemia and azotemia. In addition, all animals displayed signs of lameness due to footpad lesions that were histologically characterized as marked metastatic mineralization with granulomatous inflammation, reminiscent of calcinosis circumscripta. Although the animals were managed with aggressive fluid therapy, calciuresis, and dietary modification, all were eventually humanely euthanized due to the severity of their footpad lesions and/or progression of renal disease. Metastatic mineralization was also noted in other soft tissues among the three cases, including the stomach, colon, lung, vascular wall, ovary, and kidney. Varying degrees of interstitial nephritis were confirmed on postmortem examination, and in the absence of other causes for hypercalcemia, metastatic mineralization was presumably the consequence renal dysfunction. The renal pathway is the primary mode of calcium excretion in the rock hyrax. In renal dysfunction, hypercalcemia may develop secondary to decreased calcium excretion. Footpad mineralization is an uncommon sequel to renal dysfunction in domestic animals but has not been reported in rock hyraxes. A retrospective review of mortality data in this collection revealed a notable prevalence of renal lesions, including two additional animals with metastatic mineralization and renal dysfunction. Expanding knowledge of renal diseases will further guide preventative and clinical measures, including screening for metastatic mineralization and therapeutic trials for management of hypercalcemia and calcium mineral deposition in the footpads and other soft tissues.