RESUMO: A lesão renal aguda (IRA) é uma síndrome complexa, associada à progressão desfavorável, especialmente em cães na unidade de terapia intensiva (UTI) e apresenta alta morbidade e mortalidade. O diagnóstico de IRA requer combinação de testes laboratoriais, como a creatinina sérica e ureia, considerados pouco sensíveis e específicos para a detecção precoce de graus discretos durante a perda de função renal. O biomarcador cistatina C é considerado superior por apresentar uma melhor correlação com a taxa de filtração glomerular. No entanto, existem poucos estudos que demonstram a utilidade da cistatina C em cães na UTI. O objetivo deste estudo foi comparar a cistatina C com o nível sérico de creatinina para detectar o estágio inicial da IRA em cães em terapia intensiva. As dosagens desses analitos foram realizadas no momento da admissão, 24 e 48 horas após. A cistatina C apresentou concentrações mais elevadas em 78,6%, enquanto a creatinina sérica aumentou apenas em 28,5% dos cães. Os resultados demonstraram que a cistatina C pode ser utilizada para a detecção precoce de lesão renal aguda em cães de UTIs devido à sua maior sensibilidade em relação aos marcadores tradicionais.

Critically ill hospitalized dogs are subject to certain complications, being acute kidney injury (AKI) a common one. Early diagnosis is crucial, and Cystatin C (CysC) is a reliable and early biomarker. The International Society of Renal Interest (IRIS) states that AKI severity can be assessed by mild changes in creatinine serum levels or reduction of urine output that cannot be considered biomarkers of renal injury but failure or insufficiency. Twenty-eight dogs admitted to the Intensive Care Unit under risk factors for the development of AKI were evaluated. Blood samples were collected for determination of sCr and CysC at admission and after 24, 48, and 72 h. Urine output was measured by daily monitoring, measured by collection in a closed system. The results showed the incidence of AKI was 67.9% based on the IRIS criteria and 78.6% based on cystatin C in critically ill patients' dogs. The measurement of serum cystatin C immediately on admission to the ICU was superior in the early identification of patients with AKI when compared to the IRIS classification and serum creatinine in critically ill dogs.

The diagnosis of acute kidney injury by evaluating the activity of urinary enzymes is an important tool especially for its precocity in relation to methods of assessment of renal function considered late as the installation of injury precedes the function change. This study was performed to determine the reference interval for urinary NAG activity (N-Acetyl-β-D-glucosaminidase) in urine of healthy dogs of different breeds, ages and sexes. It was utilized an automated method for the determination of NAG activity standardized for dog urine samples. Through statistical analysis it was observed that NAG is positively correlated with the age of the animal and urine specific gravity but is not interfered by sex or weight. Based on the determination of urinary activity and after correcting the values for a 1,025 urine specific gravity was obtained an reference interval of X ‘= 3.62U/L±0.66U/L.