Pathology of the urinary system

4) Renal dysplasia

 

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a rare condition, very difficult to diagnose, but an important cause of renal failure necessitating renal 

transplantation in children; 

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by definition, renal dysplasia is an abnormal and asynchronous differentiation of renal tissues; 

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mostly idiopathic, but it has been associated with hypovitaminosis A in pigs, autosomal dominant 

inheritance in Suffolk sheep, intrauterine ureteral obstruction in calves and piglets (also in humans), 

and congenital infections (e.g. feline panleukopenia virus, canine herpesvirus, bovine virus diarrhea 

virus); 

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in cats, dogs and pigs, in which the kidneys continue to develop after birth, renal dysplasia may be 

caused by disease in the early neonatal period; 

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grossly, varies from minimal alteration (microscopic changes) to small, misshapen, fibrotic kidneys; 

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microscopically, distinct characteristics include: 

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persistence of primitive mesenchyme (myxomatous connective tissue) in cortex or medulla, 

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asynchronous differentiation of nephrons, i.e. groups of immature glomeruli (small, highly 

cellular, with inapparent capillaries) in the cortex of adolescent or adult animals, 

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collecting tubules ending blindly in cortical connective tissue, 

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persistence of mesonephric ducts (primitive ducts lined by cuboidal or columnar epithelium 

and surrounded by concentric layers of mesenchyme), 

    - 

atypical (adenomatoid) tubular epithelium, 

    - 

chondroid or osseous metaplasia; 

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because anomalies of the ureters are often concurrent, animals with renal dysplasia show increased 

susceptibility to pyelonephritis; 

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severe bilateral dysplasia usually leads to renal failure; 

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renal dysplasia must be differentiated from renal hypoplasia, renal fibrosis, and familial (hereditary) 

renal disease; it may be very difficult, if not impossible, to differentiate long-standing renal dysplasia 

from other forms of chronic renal disease.