I use a raised food dish for my dogs, but from what I have read
Vets just don't know what will prevent a dog
to bloat.

Rocky has 4 of the risk facters of his possibility to bloat.

Part of a bloat article:

Dogs weighing more than 99 pounds have an approximate 20% risk of bloat

Classically also, the dog had eaten a large meal and exercised heavily shortly thereafter. Still, we usually do not know why a given dog bloats on an individual basis. No specific diet or dietary ingredient has been proven to be associated with bloat. Some factors found to increase and decrease the risk of bloat are listed below:

Factors Increasing the Risk of Bloating

Feeding only one meal a day
Having closely related family members with a history of bloat
Eating rapidly
Being thin or underweight
Fearful or anxious temperament
History of aggression towards people or other dogs
Male dogs are more likely to bloat than females
Older dogs (7 - 12 years) were the highest risk group
Factors Decreasing the Risk of Bloat

Inclusion of canned dog food in the diet
Inclusion of table scraps in the diet
Happy or easy-going temperament
Eating 2 or more meals per day
In a study done by the Perdue University Research Group, headed by Dr. Lawrence T. Glickman: