Avaliação clínica, laboratorial e anatomopatológica do sistema urinário de ovinos confinados com ou sem suplementação de cloreto de amônio

Abstract

Resumo: A acidificação urinária com cloreto de amônio (CA) é um método preventivo eficiente em urolitíase obstrutiva em ovinos. Os objetivos deste estudo com ovinos confinados, que receberam dieta concentrada com elevado teor proteico, foram: verificar o efeito da dieta sobre a formação de urólitos e o desenvolvimento da doença; analisar as características macroscópicas e histopatológicas do sistema urinário; relacionar os achados clínicos, laboratoriais e necroscópicos com a presença de urólitos. Utilizaram-se 60 ovinos machos: grupo CA (n=40), 400 mg/kg CA/dia, tratados via oral, por 42 dias consecutivos; grupo-controle (n=20), não tratado. Determinaram-se sete momentos de colheita de amostras com intervalos de sete dias, no total de 56 dias de confinamento. Encontraram-se microcálculos na pelve renal em cinco animais de ambos os grupos. As lesões renais microscópicas mais relevantes foram congestão vascular e necrose tubular. Concluiu-se que a dieta rica em concentrado provocou lesão renal em ambos os grupos, embora sem alterar a função renal, o que foi comprovado em testes pela ureia e creatinina séricas. O cloreto de amônio fornecido ao grupo CA não impediu a calculogênese, mas reduziu sua prevalência em relação ao grupo-controle. Os ovinos do grupo-controle tiveram maior comprometimento renal, pela alta incidência de cristalúria e pela necrose tubular, induzidas pelo consumo da dieta rica em grãos.

Sheep urinary tract architecture is not affected by acute urethral obstruction

“…ureter, which may have contributed to less stone retention at this site (Table 3). These data are consistent with those described by Santarosa et al (2016), who observed unilateral Note. -(*) -significant difference between groups (P < 0.05).…”

“…The main necropsy findings of the affected animals were a full bladder with extensive area of hemorrhage, necrosis of the urethral process, and dilation of the ureter and renal pelvis (Figure 2), as reported by Lima et al (2009). Santarosa et al (2016) observed hydronephrosis and unilateral dilatation of the ureter in only one sheep without presenting clinical pain symptoms. Uroliths were mostly deposited in the urinary bladder, although they were also found in the renal pelvis and urethra, especially in the sigmoid flexure and the urethral process, the main obstruction points (Figure 3).…”

“…There were more exacerbated signs in one of the animals that presented with urethral rupture. These signs were not observed by Santarosa et al (2016), although the animals in their experiment were confined for 56 days, a time sufficient for urolith development. They were found during necropsy exclusively in the renal pelvis, without causing obstruction.…”

“…Uroliths were mostly deposited in the urinary bladder, although they were also found in the renal pelvis and urethra, especially in the sigmoid flexure and the urethral process, the main obstruction points (Figure 3). Santarosa et al (2016) reported sandy aspect calcifications exclusively in the kidneys, whereas Assis et al (2009) observed uroliths mainly in the right kidney and in the bladder outlet to the urethra and sigmoid flexure. Such findings are frequent, and their severity is directly related to the clinical evolution of the condition and the degree of obstruction.…”

“…Histopathological examination of the kidneys of three animals showed vascular lesions of inflammatory nature, such as discrete multifocal infiltrates of lymphocytes, plasma cells, and macrophages in the medular region; discrete to moderate congestion of multifocal areas of the glomerular tufts, located mainly in the medullar region; and mild presence of protein in the tubular lumen. Nevertheless, Santarosa et al (2016) described renal vascular congestion with mild and moderate presence of protein in the lumen tube in sheep urolithiasis. According to Frelier, Armstrong and Pritchard (1990) and Garcia-Navarro (2005), the presence of protein in the tubular lumen occurs due to lower resorption capacity, indicating tubular lesions, whereas post-renal proteinuria characterizes glomerular disease.…”