Also known as  "bloat "  Gastric Dilatation- Volvulus is an acute life threatening situation.
It requires immediate medical and usually surgical attention.
The term Gastric Dilatation means enlargement or distention. It is not always accompanied by the Volvulus or torsion which quite literally is twisting of the stomach on its long axis.

Once the stomach twists the stomach contents are then trapped in place and the gas contiues to build up.
when the stomach begins to expand which it does very rapidly,  it can press on major arteries and viens in the abdominal cavity thus restricting blood flow and in turn lowering blood pressure.
This is serious and once this happens the heart rate increases and the pulse becomes weak as the dog then goes into shock.

In servere cases if the stomach swells enough this may displace the spleen cutting off circulation and causing enlargement and possible twisting of the spleen .
With circulation of the stomach constricted parts of the stomach wall can necrose and die.
This is a life threantening situation and needs urgent medical surgery.
In less severe cases or if the symptoms are caught early enough  the dog can be tubed and the stomach decompressed , there is no torsion and no need for surgery.

Once a dog has bloated there is a high chance he will do so again.
Dogs who are greatest risk are large deep chested breeds.
The greater the chest depth - width ratio the greater the risk.

factors linked to bloat include -
history of belching and fLatuence 
gulping  water or food quickly 
aggression
dogs that are fed one meal a day
dogs that are highly stressed or suffering from stress.

There can also be some underlying medical conditions that lead to the dog bloating

There are so many different points of view from dog owners and experts and studys are always ongoing into bloat but here are some precautions they reccommend to help deter bloating - 

If possible feed small meals little and often and always feed two meals a day .
Never attempt vigorous excercise for one hour before and two hours after eating.
Do not feed dry biscuit meal alone moisten the biscuit first if you do not add meat .
Miminise stress especially at meals times 
Raising the bowl off the floor
( it does help although some people dispute this theory) this way is better than a food bowl on the floor as less air is gulped in when eating from a slighly rasied position.
Try placing an object in the middle of the bowl such as a heavier smaller bowl or a tin
this sometimes works with dogs that gulp food as they have to eat around the object and cannot stick their head fully in the bowl and start gulping the food thus gulping in air .

Whatever the case if you notice any of the following symtoms
SEEK MEDICAL HELP QUICKLY - 
The dog pacing
Difficulty in walking
Excessive panting
Discomfort and agitation
Depression
Drooling and foaming 
Frothing at the mouth
Unproductive vomiting or retching
Distention of the stomach 
The stomach looking grossly large and hard to the touch
Any general or unusal unwellness in your dog