Polycystic kidney disease in the pygmy hippopotamus (Hexaprotodon liberiensis)

Polycystic kidney disease (PKD) was diagnosed at necropsy in a captive aged female pygmy hippopotamus (Hexaprotodon liberiensis), which presented with numerous cysts in both kidneys, the liver, and the duodenum and with one single cyst in the pancreas. There were no premonitory clinical signs of a nephropathy observed prior to its death. Similar findings were made in a male cage mate 6 mo later. Both animals had been wild caught. A literature review revealed 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 indicated familiar transmission similar that associated with PKD in humans and other animals. The disease, and especially the presumptive bias in diagnosis toward females, indicated that the male animal of this report was the first case of PKD reported in a male pygmy hippopotamus; thus, further investigation is warranted. The status of the kidneys with respect to PKD should be assessed (including histology) in every deceased pygmy hippopotamus, and whenever possible by ultrasonography in live animals.