There are a couple things that come to mind, one being IBS(irritable bowel syndrome) and the other would be a pancreatic deficancy.
Their tummy will also growl if they have an intestinal parasite problem that has not been diagnosed.
If this continues, you should see the vet for a fecal exam and a general look-see to see what's going on.
Many people complain about this after their dogs have eaten grass. And you will often see this noise if a dog has consumed garbage or eaten something that has not agreed with them. If you suspect this, you can try to ease some of the gas pain and stomach upset by offering her only a bland diet of only boiled chicken and white rice until she is past this spell. This is often soothing to the stomach.
Some dogs can get some relief with some Zantac as well.
Let me know if you still have questions.
If this is simple constipation, you can give him 1 tsp of canned pumpkin and this will help him move his bowels. It's really hard to treat it at home, especially if you don't know the cause.
If he is not moving his bowels, you might fear an obstruction. If this is the case (or if he has liquid diarrhea), you will want to see your vet right away.