Large amount of nitric oxide (NO) can be released in patients with sepsis. Methemoglobin is formed from the interaction between NO and hemoglobin. Mild methemoglobinemia reflecting NO overproduction has been reported in septic people, and occasionally associated to septic shock and organ dysfunction. The aim of this retrospective study was to evaluate circulating methemoglobin fraction in dogs with sepsis and to assess its prognostic value. Methemoglobin reference interval (RI) was calculated in 41 healthy dogs and was set at 0–2.2%. A total of 131 dogs with sepsis were included in the study; 24/131 had a circulating methemoglobin ≥2.2%. The median methemoglobin fraction was significantly higher in dogs with sepsis compared to healthy ones (1.7%, 0.4–3.5% vs. 1.0, 0.3–2.2%, P = 0.0005). No significant difference was observed between dogs with uncomplicated sepsis (n = 98) vs. dogs with septic shock (n = 33) (1.8%, 0.4–2.8% vs. 1.5%, 0.4–3.5%, P = 0.74), between dogs with and without multi-organ dysfunction (n = 38 and n = 93, respectively) (1.7%, 0.4–3.5% vs. 1.7%, 0.5–2.8%, P = 0.27), and between survivors (n = 77) vs. non survivors (n = 54) (1.5%, 0.4–2.8% vs. 1.8%, 0.4–3.5%, P = 0.05). Dogs with methemoglobin fraction above or equal to the upper limit of the RI had a significantly higher frequency of death compared to dogs with methemoglobin levels <2.2% (60.0% vs. 36.8%, P = 0.04). In conclusion, mild methemoglobinemia is detected in dogs with sepsis, and methemoglobin values above the RI might be associated with a worse outcome.

败血症患者可释放大量的一氧化氮（NO）。高铁血红蛋白是由NO和血红蛋白之间的相互作用形成的。在脓毒症患者中报告了轻度的高铁血红蛋白血症，反映出NO过量产生，偶而与脓毒症休克和器官功能障碍有关。这项回顾性研究的目的是评估脓毒症犬循环中的高铁血红蛋白含量，并评估其预后价值。计算了41只健康犬的高铁血红蛋白参考间隔（RI），其设定为0-2.2％。研究共纳入131只败血症犬；24/131的循环高铁血红蛋白≥2.2％。脓毒症犬的高铁血红蛋白中位数比健康犬高得多（1.7％，0.4-3.5％比1.0、0.3-2.2％，P= 0.0005）。败血症简单的狗之间没有观察到显着差异（ñ = 98）与患有败血性休克的狗（ñ = 33）（1.8％，0.4–2.8％与1.5％，0.4–3.5％， P = 0.74），在有和没有多器官功能障碍的狗之间（ñ = 38并且 ñ 分别为93）（1.7％，0.4-3.5％和1.7％，0.5-2.8％， P = 0.27），以及幸存者之间（ñ = 77）与非幸存者（ñ = 54）（1.5％，0.4–2.8％与1.8％，0.4–3.5％， P= 0.05）。高铁血红蛋白含量高于或等于RI上限的狗比高铁血红蛋白水平<2.2％的狗有更高的死亡频率（60.0％比36.8％，P= 0.04）。总之，在败血症犬中检测到轻度高铁血红蛋白血症，高于RI的高铁血红蛋白值可能与更差的预后相关。