Get Your Dog Care Questions Answered by Experts
Hello and thank you for using this site to help you.
These are symptoms consistent with intestinal parasites if the dog is otherwise eating , drinking and acting normally and all other aspects of the dogs life is normal showing no other pain or acting in discomfort.
I would make sure to try to bring in a sample of stool when you see your Vet on Monday.
Here is a good article that goes over how dogs contract these , and symptoms http://www.pethealthnetwork.com/dog-health/dog-diseases-conditions-a-z/intestinal-parasites-dogs
Other causes are more serious such as fluid building in the abdomen from a puncture to intestines , hemorraging etc. This would be seen as an emergency. If you explained the circumstance to your vet them may not think it an emergency and that is why they scheduled you for Monday. However if this does not feel right to you seek out another Vet's service. Never be afraid to do that.
here are other causes /diseases for extended belly's.