A comparison of the plasma fructose concentrations in dogs and cats and changes in the fructose concentrations in dogs following intravenous administration of fructose

The plasma concentrations of fructose, glucose, free fatty acids (FFA) and triglycerides (TG) were measured in dogs and cats. Changes in these concent rations were investigated in dogs by an intravenous fructose tolerance test (IVFTT) at a dose of 0.1 g/kg body weight. Fructose concentrations in the plasma of dogs were significantly higher than those of cats. There was no s ignificant difference in plasma glucose concentrations between dogs and cat s. Plasma FFA concentrations decreased and TG concentrations increased afte r feeding in both dogs and cats. During the IVFTT, the plasma fructose conc entrations in the dogs increased rapidly to a peak by 2 min and then decrea sed to half of the peak by 5 min after the administration of fructose. Admi nistration of fructose resulted in an increase in the plasma TG concentrati ons and reduced plasma FFA concentrations in the dogs. Only 4% of the admin istered fructose was detected in the urine of dogs following IVFTT. Plasma fructose was considered to be rapidly absorbed and metabolized in both dogs and cats. However, as with glucose metabolism, there appear to be some dif ferences in fructose metabolism between dogs and cats.