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Obstruções Ureterais em Gatos: Abordagem Diagnóstica e Tratamento
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Abstract(s)
Os ureteres dos gatos possuem um diâmetro intraluminal extremamente reduzido (0,3 a 0,4
mm), o que os torna particularmente predispostos à ocorrência de obstruções ureterais. A etiologia
mais comum é a ureterolitíase, sendo que cerca de 98% dos urólitos ureterais são compostos por
oxalato de cálcio. A obstrução pode afetar um ou ambos os ureteres, o que tem implicações diretas no
diagnóstico e prognóstico da condição. Os sinais clínicos associados são, na sua maioria, inespecíficos,
dificultando o diagnóstico precoce. Entre os mais comuns destacam-se: letargia, anorexia, vómitos,
poliúria, polidipsia e dor abdominal. Para um diagnóstico definitivo e avaliação prognóstica é essencial
recorrer a exames complementares de diagnóstico, incluindo hematologia (frequentemente revelando
anemia), análises bioquímicas (com evidência de azotémia), urinálise (identificando hematúria, piúria,
bacteriúria e cristalúria) e exames de imagem, como radiografia abdominal e, principalmente,
ecografia, que permite identificar alterações renais e causas obstrutivas, mesmo quando
radiolucentes. A obstrução ureteral, quando não tratada, conduz a lesões renais progressivas e resulta
em insuficiência renal aguda. O plano terapêutico pode ser médico e/ou cirúrgico. O tratamento
médico visa restaurar a função renal através de fluidoterapia, uso de diuréticos, relaxantes do músculo
liso ureteral e antibioterapia, especialmente na presença de infeções urinárias associadas. Nos casos
em que o tratamento médico não é suficiente, recorre-se à intervenção cirúrgica, que pode incluir
técnicas como ureterotomia, ureterostomia, remoção de cálculo com anastomose ou
ureteroneocistostomia. A técnica mais utilizada atualmente é o Subcutaneous Ureteral Bypass (SUB),
que permite a derivação do fluxo urinário contornando o ureter obstruído. Em situações específicas,
como estenoses ureterais, técnicas mais recentes como o Boari flap têm vindo a ser implementadas
com bons resultados. A monitorização rigorosa dos animais afetados é essencial para a deteção
precoce de complicações e para o sucesso do tratamento. A prevenção da recorrência passa,
sobretudo, pela adoção de medidas dietéticas apropriadas que minimizem a formação de cristais
urinários.
The feline ureters have an extremely narrow intraluminal diameter (0,3 to 0,4 mm), which renders this species particularly predisposed to ureteral obstructions. The most common etiology is ureterolithiasis, with approximately 98% of ureteral uroliths composed of calcium oxalate. Obstruction may affect one or both ureters, which has direct implications for both diagnosis and prognosis. The clinical signs associated with ureteral obstruction are often nonspecific, making early diagnosis challenging. The most frequently observed signs include lethargy, anorexia, vomiting, polyuria, polydipsia, and abdominal pain. Definitive diagnosis and prognosis require complementary diagnostic tests, including hematology (commonly revealing anemia), biochemical analysis (with evidence of azotemia), urinalysis (demonstrating hematuria, pyuria, bacteriuria, and crystalluria), and diagnostic imaging such as abdominal radiography and, more importantly, ultrasonography, which is useful in identifying renal changes and obstructive causes even when radiolucent. If left untreated, ureteral obstruction leads to progressive renal damage and results in acute renal failure. The therapeutic approach may be medical and/or surgical. Medical treatment aims to restore renal function through fluid therapy, use of diuretics, smooth muscle relaxants, and antibiotic therapy, particularly in the presence of concurrent urinary tract infections. When medical management proves insufficient, surgical intervention becomes necessary. Surgical options include ureterotomy, ureterostomy, stone removal with anastomosis, or ureteroneocystostomy. Currently, the most commonly used technique is the Subcutaneous Ureteral Bypass (SUB), which enables urinary flow to bypass the obstructed ureter. In specific situations, such as ureteral strictures, newer techniques such as the Boari flap have shown promising results. Close monitoring of affected animals is essential for early detection of complications and for ensuring treatment success. Preventive strategies, particularly the adoption of appropriate dietary measures, play a key role in minimizing the recurrence of urinary crystal formation.
The feline ureters have an extremely narrow intraluminal diameter (0,3 to 0,4 mm), which renders this species particularly predisposed to ureteral obstructions. The most common etiology is ureterolithiasis, with approximately 98% of ureteral uroliths composed of calcium oxalate. Obstruction may affect one or both ureters, which has direct implications for both diagnosis and prognosis. The clinical signs associated with ureteral obstruction are often nonspecific, making early diagnosis challenging. The most frequently observed signs include lethargy, anorexia, vomiting, polyuria, polydipsia, and abdominal pain. Definitive diagnosis and prognosis require complementary diagnostic tests, including hematology (commonly revealing anemia), biochemical analysis (with evidence of azotemia), urinalysis (demonstrating hematuria, pyuria, bacteriuria, and crystalluria), and diagnostic imaging such as abdominal radiography and, more importantly, ultrasonography, which is useful in identifying renal changes and obstructive causes even when radiolucent. If left untreated, ureteral obstruction leads to progressive renal damage and results in acute renal failure. The therapeutic approach may be medical and/or surgical. Medical treatment aims to restore renal function through fluid therapy, use of diuretics, smooth muscle relaxants, and antibiotic therapy, particularly in the presence of concurrent urinary tract infections. When medical management proves insufficient, surgical intervention becomes necessary. Surgical options include ureterotomy, ureterostomy, stone removal with anastomosis, or ureteroneocystostomy. Currently, the most commonly used technique is the Subcutaneous Ureteral Bypass (SUB), which enables urinary flow to bypass the obstructed ureter. In specific situations, such as ureteral strictures, newer techniques such as the Boari flap have shown promising results. Close monitoring of affected animals is essential for early detection of complications and for ensuring treatment success. Preventive strategies, particularly the adoption of appropriate dietary measures, play a key role in minimizing the recurrence of urinary crystal formation.
Description
Keywords
Obstrução ureteral Oxalato de cálcio Subcutaneous ureteral bypass Tratamento médico Urolitíase Calcium oxalate Medical treatment Ureteral obstruction Urolithiasis