ABSTRACT
BACKGROUND: Paraoxonase-1 (PON-1) has been suggested as a marker of inflammation and oxidative stress in horses and could potentially be used for prognostication in horses with colitis. OBJECTIVES: Assessment of PON-1 in horses with colitis and comparison of two methods. METHODS: Serum PON-1 was measured by two methods (paraoxon and p-nitrophenyl acetate) in 161 horses with colitis and 57 controls. Follow-up samples obtained during hospitalization were available from 106 horses with colitis. The two methods were compared. RESULTS: Serum PON-1 was significantly lower in horses with colitis than in healthy horses (P < .0001 for both methods) as well as in nonsurvivors compared with survivors (P = .0141 [paraoxon-based method] and P < .0001 [p-nitrophenyl acetate-based method]), but with marked overlap between groups. PON-1 activity did not change parallel to a change in inflammatory status in response to treatment when assessed at admission and in up to seven follow-up samples. Admission PON-1 activity could not reliably classify horses as survivors or nonsurvivors, with sensitivity and specificity ranging between 53.1% and 72.9%. Results from the two methods were comparable. CONCLUSIONS: Both methods reliably measured serum PON-1 activity. Significant differences in PON-1 activity were found between healthy horses and horses with colitis and between survivors and nonsurvivors. However, PON-1 activity varied considerably within groups. Both the proposed reference intervals as well as alternative cutoff values resulted in suboptimal diagnostic and prognostic performance, and the use of serum PON-1 in horses with colitis thus seems to add little to existing diagnostic and prognostic markers.
ABSTRACT
BACKGROUND: Neutrophil gelatinase-associated lipocalin (NGAL) is produced in response to inflammation in horses, but it has not yet been investigated as a biomarker in horses with the abdominal disease. OBJECTIVES: To investigate NGAL in serum and peritoneal fluid in horses with the abdominal disease. STUDY DESIGN: Retrospective clinical study. METHODS: Data from medical records of 270 horses admitted with acute abdominal disease (simple obstructions [n = 43], strangulating obstructions [n = 104], inflammatory abdominal disease [n = 99], non-strangulating intestinal infarction [NSII, n = 24]) and 9 healthy control horses were reviewed, and serum and peritoneal fluid samples were retrieved from a biobank. NGAL was measured in serum and peritoneal fluid by ELISA. Differences in NGAL concentrations between groups were assessed. RESULTS: Healthy horses had low serum and peritoneal fluid concentrations of NGAL (median = 21.0 and 9.5 µg/L, respectively). Neither serum nor peritoneal fluid NGAL concentrations (median serum, peritoneal fluid) differed between healthy horses and horses with simple (28.1 µg/L, 13.0 µg/L) and strangulating intestinal obstructions (34.7 µg/L, 38.4 µg/L). Horses with NSII (308.0 µg/L, 2163.0 µg/L) and inflammatory abdominal disease (171.1 µg/L, 314.1 µg/L) had higher serum and peritoneal fluid concentrations of NGAL than the other groups (p < 0.001). Peritoneal fluid NGAL concentrations in horses with NSII were higher than in horses with inflammatory abdominal disease (p = 0.03). MAIN LIMITATIONS: Retrospective study design; small group of control horses. CONCLUSIONS: NGAL is a marker of inflammation in horses with the abdominal disease. The high peritoneal fluid concentration of NGAL in horses with NSII compared to all other groups may render NGAL useful for identifying this condition, which is otherwise difficult to differentiate from other types of peritonitis. Thereby, NGAL may potentially facilitate timely surgical intervention in this group of patients. The results of this study must be evaluated in larger, and preferably prospective, studies to obtain a more comprehensive evaluation of the diagnostic utility of NGAL.
CONTEXTO: Lipocalina associada à gelatinase de neutrófilos (NGAL) é produzida em resposta à inflamação em equinos, mas ainda não foi investigada como biomarcador de equinos com doenças abdominais. OBJETIVOS: Investigar a NGAL no soro e líquido peritoneal (LP) de equinos com doenças abdominais. DELINEAMENTO DO ESTUDO: Estudo retrospectivo. METODOLOGIA: Informação de prontuários médicos de 270 equinos com doença abdominal (obstrução simples [n = 43], obstrução estrangulante [n = 104], doença abdominal inflamatória [n = 99], lesão de infarto não estrangulante [NSII, n = 24]) e nove equinos saudáveis como controle foram revisados, e o soro e LP foram obtidos de um biobank. NGAL foi mensurado no soro e LP através de ELISA. Diferenças na concentração de NGAL entre os grupos foi avaliada. RESULTADOS: Cavalos saudáveis tiveram concentração de NGAL baixas no soro e no LP (mediana = 21.0 e 9.5 µg/L, respectivamente). A concentração de NGAL no soro e no LP não diferiram entre cavalos saudáveis e cavalos com obstrução simples (28.1,13.0) e obstrução estrangulante (34.7, 38.4). Cavalos com NSII (308.0, 2163.0) e doença abdominal inflamatória (171.1314.1) tiveram concentrações mais altas de NGAL no soro e LP quando comparados aos outros grupos (p < 0.001). A concentração de NGAL no LP em cavalos com NSII foi mais alta do que em cavalos com doença abdominal inflamatória (p = 0.03). PRINCIPAIS LIMITAÇÕES: Delineamento de estudo retrospectivo e pequeno grupo de equinos controle. CONCLUSÕES: NGAL é um marcador de inflamação em cavalos com doença abdominal. A concentração alta de NGAL no LP de cavalos com NSII comparado com os outros grupos indica que NGAL pode ser útil em identificar essa condição, o que é usualmente difícil de diferenciar de outros tipos de peritonite. Contudo, NGAL tem o potencial de facilitar a decisão rápida da necessidade de intervenção cirúrgica nesse grupo de pacientes. Os resultados deste estudo devem ser avaliados em uma população maior (e preferencialmente prospectiva) para obter uma melhor avaliação compreensiva da utilidade diagnóstica do NGAL.
