The effect of long-term fasting on ketone body metabolism in the dog.

Ketone-body metabolism was studied in overnight-fasted and in 10-days fasted dogs by a ketone-body tolerance test and by infusing [14C]ketone bodies. Clearance of ketone bodies from the blood was significantly decreased after 10 days of fasting. The utilization of ketone bodies was, however, significantly higher in the fasted animals due to the increase in blood ketone-body concentrations. It is concluded that the low level of ketone bodies, which is characteristic for fasting dogs, results from an efficient peripheral utilization. The contribution of ketone bodies to the daily energy requirement of the dog has been tentatively estimated to increase from 7% in the overnight-fasted state to 13% after 10 days of starvation.