Hereditary Nephritis-Samoyed Hereditary Glomerulopathy (HN)
Hereditary nephritis in the Samoyed is a dominant, X-linked disease that affects young male dogs more severely than females. Affected males and females spontaneously develop proteinuria, but only males progress to renal failure. Male pups with hereditary glomerulonephropathy usually show signs by 2 to 3 months of age. They begin to lose weight dramatically and kidney function deteriorates rapidly, resulting in death by an early age (approximately 1 year). Females who carry the disease also lose weight and develop proteinuria between two and three months of age, but the disease is less severe and does not progresses to kidney failure.
Dominant inheritance occurs when an abnormal gene from ONE parent is capable of causing disease, even though a matching gene from the other parent is normal. The abnormal gene dominates the gene pair. Males have 1 X chromosome from their mother, and 1 Y chromosome from their father, which carries little information other than maleness. Females have 2 X chromosomes, 1 each from their mother and father. For an X-linked dominant disorder: If the father carries the abnormal X gene, all of his daughters will inherit the disease and none of his sons will have the disease. If the mother carries the abnormal X gene, half of all their children (daughters and sons) will inherit the disease tendency.
Hereditary nephritis has also been reported in English Cocker Spaniel and Bull Terrier dogs, however, the mode of inheritance is different from that of Samoyed dogs. While the severity of problems and rate of progression varies between breeds and between individual dogs, the end result is the same-kidney failure for the dog, generally by 5 years of age.