Mechanisms of xylitol toxicosis in dogs

摘要

In the present literature review, the mechanisms of xylitol toxicosis in dogs are summarized and discussed by the authors. Xylitol, which is now widely used as a sweetener in human nutrition, causes a severe, commonly life-threatening toxicosis in dogs, being an emerging issue in small animal veterinary practice. In dogs, xylitol is being absorbed especially fastly and almost completely from the small intestines by active transport mechanisms, getting metabolized in the liver and pancreatic beta cells, mostly via the pentose phosphate pathway. At first, the toxicity of xylitol is related to its strong stimulatory action on pancreatic insulin release, causing severe hypoglycaemia. As xylitol is rapidly converted to glucose 6-phosphate, a fuel molecule for the biological oxidation, it may stimulate insulin synthesis and exocytosis in beta cells by enhancing the intracellular calcium concentration via the increased ATP/ADP ratio. However, the exact details of the xylitol-induced intense insulin response in dogs are not fully elucidated yet. Further, xylitol can provoke necrosis and damage of liver cells, which might be in connection with the insulin-triggered hepatocellular energy deficiency, the formation of immune complexes and xylitol-associated increased oxidative stress. Concerning the toxicity of xylitol, there are enormous differences among species, which is supposed to be related to xylitol's species-dependently different kinetic and metabolic properties. The authors would like emphasise out that further investigations are needed to study the mechanisms of xylitol toxicosis more deeply, which may provide useful information for the veterinary clinical praxis, as well by possibly improving the clinical management of xylitol toxicosis in dogs.