Symptoms of Bloat

Bloat in Dogs: "Typical symptoms often include some (but not necessarily all) of the following, according to the links below. Unfortunately, from the onset of the first symptoms you have very little time (sometimes minutes, sometimes hours) to get immediate medical attention for your dog. Know your dog and know when it's not acting right.
Attempts to vomit (usually unsuccessful); may occur every 5-20 minutes
This seems to be one of the most common symptoms & has been referred to as the 'hallmark symptom'
Doesn't act like usual self
Perhaps the earliest warning sign & may be the only sign that almost always occurs
Significant anxiety and restlessness
One of the earliest warning signs and seems fairly typical
'Hunched up' or 'roached up' appearance
This seems to occur fairly frequently
Bloated abdomen that may feel tight (like a drum)
Despite the term 'bloat,' many times this symptom never occurs or is not apparent
Pale or off-color gums
Dark red in early stages, white or blue in later stages
Lack of normal gurgling and digestive sounds in the tummy
Many dog owners report this after putting their ear to their dog's tummy
Coughing
Unproductive gagging
Heavy salivating or drooling
Foamy mucous around the lips, or vomiting foamy mucous
Unproductive attempts to defecate
Whining
Pacing
Licking the air
Seeking a hiding place
Looking at their side or other evidence of abdominal pain or discomfort
May refuse to lie down or even sit down
May stand spread-legged
May attempt to eat small stones and twigs
Drinking excessively
Heavy or rapid panting
Shallow breathing
Cold mouth membranes
Apparent weakness; unable to stand or has a spread-legged stance
Especially in advanced stage
Accelerated heartbeat
Weak pulse
Collapse

--Bloat is a very serious and often fatal disorder, know the symptoms and seek veterinary care immediately if you suspect your dog has bloat!