Clinical bottom line:
The available evidence is mixed and of variable quality. Most evidence indicates that rate of eating has no effect on risk of gastric dilatation; volvulus (GDV). Where significant effects occur, fast eating was implicated as a risk factor. No studies found that slow eating was significantly associated with an increased risk of GDV. Slowing the rate at which a dog consumes a meal will not increase risk of GDV but it may possibly reduce the risk. Based on the limitations and unreliability of the current relevant literature there is not enough evidence to make a conclusion either way.