Polycystic kidney disease in the pygmy hippopotamus (Hexaprotodon liberiensis)

Abstract

Polcystic kidney disease (PKD) was diagnosed at necropsy in a captive aged female pygmy hippopotamus (Hexaprotodon liberiensis), which presented with numerous cysts in both kidneys, liver, duodenum and one single in the pancreas. There were no premonitory clinical signs of a nephropathy observed prior to its death. Similar findings were made in the male partner animal half a year later. Both animals had been wild-caught. A literature review showed that another seven cases of PKD have been reported in pygmy hippopotamuses, and an additional screening of records available from the international studbook for the species revealed yet another six cases. In all cases, aged females were affected, and in several instances, affected animals were related to each other. These patterns suggested familiar transmission, similar to PKD in humans and other animals. The disease, and especially the presumptive bias in diagnosis towards females – the male animal of this report was to our knowledge the first case of PKD reported in a male pygmy hippopotamus -, warrant further investigation. The status of the kidneys with respect to PKD should be assessed (including histology) in every deceased pygmy hippopotamus.