When the kidneys fail to mature, there is decreased renal reserve and the dog is predisposed to progressive renal failure early in life. Renal dysplasia is congenital and may be genetically determined. Confusion arises because the changes of RD seen by kidney biopsy look the same whether the cause was genetic or environmental. Since most affected dogs are without a history of neonatal illness, since they are genetically related, and since RD is diagnosed in the SCWT with much higher frequency than expected, we strongly suspect RD in the SCWT is an inherited trait. The exact mode of inheritance is not worked out.
More confusion arises because of gradations of severity of the kidney maldevelopment.
Most dogs with RD die before 2 years of age. Most dogs with PLN show their illness at age 5-7 years. Most dogs with RD cannot concentrate their urine well, even early-on before the blood test values are abnormal. The USG is often low. Because they lose more water in their urine, these dogs need to drink more than normal dogs, lest they become dehydrated.