Achados patológicos em caninos com displasia renal no Sul do Brasil

Abstract

RESUMO.-A displasia renal resulta de um distúrbio na nefrogênese, com diferenciação anormal dos rins, podendo ser unilateral ou bilateral, e causa insuficiência renal em cães jovens. Qualquer agente agressor, incluindo vírus, pode causar a lesão até três meses após o nascimento, quando encerra o desenvolvimento embrionário do néfron. Foram diagnosticados 11 casos de displasia renal dentre 186 casos de cães com insuficiência renal de um total de 5.846 cães submetidos à necropsia no Setor de Patologia Veterinária da Universidade Federal do Rio Grande do Sul no período 2002-2013. Amostras teciduais coletadas na necropsia foram fixadas em 10% de formol e coradas com hematoxilina e eosina (HE) e tricrômico de Masson. Na necropsia, os rins estavam pálidos, diminuídos de tamanho, irregulares e firmes, com diâmetro da cortical diminuído. Alguns ainda eram císticos e apresentavam estriações brancacentas paralelas dispostas radialmente na medular. Ao exame histológi-co os rins exibiam lesões primárias e secundárias. As lesões primárias identificadas foram glomérulos e túbulos fetais, diminuição quantitativa de glomérulos, túbulos adenomatosos e persistência de ductos metanéfricos. Renal dysplasia results from a disturbance which occurs during nephrogenesis. The disease may be unilateral or bilateral, and leads to abnormal kidney differentiation leading to renal failure in young dogs. Several agents, including viruses, can cause the dysplasia till three months after birth, when the early nephron formation of the developing kidney is completed. Eleven renal dysplasia cases were diagnosed in 186 dogs with renal failure of 5,846 dogs necropsied in the Veterinary Pathology Sector, Federal University of Rio Grande do Sul, in the period 2002-2013. Tissue samples collected during necropsy were fixed in 10% formaldehyde and stained with hematoxylin-eosin (HE) and Masson's trichrome protocol. Upon necropsy, kidneys were pale, smaller than normal, irregular and firm, and presented lower cortex diameter. Some exhibited cysts and whitish, parallel radially arranged striae in the medulla. Primary and secondary renal lesions were observed during histological examination. Primary lesions included fetal glomeruli and tubules, quantitative reduction in glomeruli, adenomatous tubules, and persistence of metanephric ducts. As for secondary lesions, Masson trichrome staining revealed intense interstitial fibrosis in all cases; furthermore, dilation of tubules and of Bowman's capsules, glomerular atrophy, and glomerulosclerosis were observed. Even though most cases were associated with breed, the results obtained indicate high prevalence of renal dysplasia in mixed-breed dogs, possibly because they were the majority of animals referred for necropsy. Although primary lesions were easily identified using HE, Masson's trichrome protocol is useful to characterize the extent of fibrosis.

Renal Dysplasia in a Maltese dog

“…Polyuria and polydipsia result from the inability of the kidneys to concentrate urine even though the animal is dehydrated, due to loss of hypertonicity of the medullary interstitium and high filtrate flow in the remaining nephrons [7]. Anorexia and vomiting are the result of stimulation of the chemoreceptor zone by uremic toxins, gastritis that develops due to direct injury by uremic toxins, and by increased gastrin concentrations, causing excessive production of gastric acid and production of ammonia from urea [2].…”

“…Chronic renal failure (CRF) is a clinical syndrome and an important cause of morbidity and mortality in dogs and cats [2,13]. Regardless of the etiology, during the evolution of a chronic renal disease, glomerular, tubular, and interstitial involvement of the glomerulus occurs, resulting in morphofunctional changes and consequent reduction in the glomerular filtration rate (GFR) [13].…”

“…Regardless of the etiology, during the evolution of a chronic renal disease, glomerular, tubular, and interstitial involvement of the glomerulus occurs, resulting in morphofunctional changes and consequent reduction in the glomerular filtration rate (GFR) [13]. It is characterized by a decreased ability to concentrate urine, clinically manifested by polyuria, and by the difficulty to maintain water and electrolyte homeostasis [2]. When CRF occurs in young dogs, it is usually associated with juvenile or familial nephropathies [4,7], which include disorders such as agenesis, renal dysplasia and hypoplasia, primary cystic disease, tubulo-interstitial diseases, glomerulopathies, and tubular dysfunction [7].…”