Your beloved basset hound is low to the ground. So is the basset hound because of his body shape.
Formally known as gastric torsion, bloat occurs when your basset's stomach fills with air and gas. It can progress to gastric dilatation volvulus, which means that the stomach twists, cutting off your dog's blood supply. Without immediate surgery, gastric dilatation volvulus causes death. While it usually occurs in big dogs, bassets are vulnerable to bloat because of their large, wide chests.
Bloat comes on very suddenly. Your lovable hound might be his happy self one minute, and extremely sick an hour later. It's generally obvious that the dog is in pain. He'll pace around, drool a lot, have difficulty breathing and possibly try vomiting without anything coming up. His tummy will be bloated and hard. Check his gums -- they're probably pale and bluish. He might even collapse. Don't waste a moment -- take him to an emergency vet right away. If his stomach twists, only surgery can save him.
The vet takes X-rays of your basset's stomach to see if there is a twist. She can't tell simply by examining the dog. If the stomach hasn't twisted, she'll insert a tube down his esophagus for relief of gas pressure. If the stomach has twisted, emergency surgery is necessary to put the stomach back in its proper location.
If a basset bloats once, he's likely to do it again. Your vet might recommend an operation called stomach tacking, which prevents the stomach from twisting. If your basset has never bloated and you want to keep it that way, feed him several small meals a day rather than one large serving. Feed canned food or wet down his kibble. Avoid feeding him for at least an hour after strenuous exercise -- yes, bassets can work up the equivalent of a doggie sweat. Don't feed him when he's excited about something, such as a squirrel in the backyard.