Inherited renal cysts in pigs: results of breeding experiments.
A landrace boar with a previous history of siring progeny with cystic kidneys was bred to five unrelated large white sows. Thirty-eight of 61 progeny (62 per cent) were affected with renal cysts. This incidence does not differ significantly from that expected with autosomal dominant inheritance. Three of the dams and the boar were found at post mortem examination to have renal cysts. The number of cysts may be determined by polygenic inheritance. Study of the pathology of the cysts in one-day-old, 25- to 32-day-old and 370-day-old progeny indicated a complex pathogenesis including probable recruitment to the cyst population throughout the period studied. The syndrome studied did not resemble previously described polycystic syndromes of the pig nor was it closely comparable to any of the well described polycystic syndromes and renal cystic disorders of man.
Renal cysts in pigs: prevalence and pathology in slaughtered pigs from a single herd.
An abattoir investigation into kidney condemnations due to renal cysts in pork pigs from one producer showed a prevalence of 47.5 per cent. Affected pigs were the progeny of a landrace boar. Similar cysts found in a small sample of day-old piglets sired by the same boar indicated a congenital origin. A marked variation in size and frequency of cysts in the kidneys of slaughtered pigs was seen, some resembling the severity of polycystic kidneys. Histologically cysts appeared to be of tubular origin. The prevalence of affected pigs in slaughter groups from the single herd could be genetically determined. If this were so the data would be consistent with autosomal dominant inheritance. A breeding experiment to examine this hypothesis is in progress.
Renal cysts are thin-walled fluid filled structures which develop in the renal parenchyma. They vary in size from barely visible to very large, often exceeding the size of the affected kidney. They may be solitary or multiple. Most often, they are a congenital anomaly; however, some develop postnatally. They have been reported in all species but they seem to occur most commonly in swine. Renal cysts can arise in any part of the nephron or in collecting tubules and most congenital cysts are not caused by an obstructive lesion. There may be some association between renal dysplasia and the formation of renal cysts because most dysplastic kidneys also have cysts. In some cases, polycystic kidney disease is also associated with cystic bile ducts, bile duct proliferation, and cystic pancreatic ducts. In severe cases of congenital polycystic kidneys, there is usually stillbirth or early neonatal death due to kidney failure.