Renal dysplasi (RD) is a congenital chronic renal disease affecting young dogs. It is a rather common disease that occurs in a large number of dogs and in some breeds there is a familiar incidence or suspected hereditary background. Both the etiology and pathogenesis are still unknown, but a theory about the cause of RD is that the two components that form the kidney, the uretheric bud and the metanephrogenic blastema, don´t interact normally in the embryo. Kidneys affected by RD contain fetal (immature) structures that are inappropriate for the state of development/age of the dog and abnormal structures caused by an abnormal differentiation. Affected dogs usually are under .

Bull terrier hereditary nephritis is caused by a mutation that leads to an inadequate synthesis of collagen type IV, which is an important component in the basement membranes. The inheritance of the mutation is autosomal dominant in bull terriers and progression to renal failure takes variable time, from several months to ten years. Proteinuria is the first clinical sign of the disease and the diagnosis is confirmed by transmission electron microscopy of renal tissue where typical ultrastructural changes in the glomerular basement membrane (GBM), thickening and multilaminar splitting are found. This study was performed in order to find out the occurrence of hereditary nephritis in bull terriers in Sweden through examination of urine samples and renal tissue and comparisons with how the disease is described in the literature. Urine samples from 76 Swedish bull terriers were collected and examined for proteinuria.

Renal dysplasia is a developmental anomaly of the kidneys which is considered to be the primary lesion in juvenile progressive nephropathy, a condition leading to chronic renal failure in young dogs. It is defined as disorganised development of the renal parenchyma due to abnormal differentiation, and pathological lesions include persistent foetal structures, dysplastic tubules and cartilaginous and osseus metaplasia. The aetiology of renal dysplasia in dogs is still unknown, but possible causes are infection with canine herpesvirus, teratogenic substances or intrauterine ureteral obstruction. In some breeds renal dysplasia is a familial or inherited disease. Clinical signs of chronic renal failure, such as polyuria, polydipsia, vomiting, weight loss, anorexia, lethargy and anemia, usually appear before the age of 2 years.