Bloat:

Also known as gastric dilation, bloat can occur in any breed.
In deep-chested breeds, like the Leonberger, the stomach can fill with gas and twist trapping the gas inside.
This is a life-threatening event which must be treated immediately.

As a preventative measure, Leonbergers should take their food in two or three meals a day, so not all in one meal,

Leonbergers should not be vigorously exercised or stressed for at least one hour after feeding.