My name is ***** ***** I’ve been involved professionally with dogs in the health and behavioral fields for over 18 years. It will be my pleasure to work with you today.
It always worries me to hear about a dog with a distended stomach as this could indicate bloat. Bloat (Gastric Dilatation) may or may not involve stomach torsion (twisted stomach). Common symptoms are attempts to vomit (usually unsuccessful) and may continue to try to vomit, dog just doesn't seem like themselves, a hunched up posture, anxiety and restlessness, a distended stomach that is tight like a drum, gums may be dark red in early stages and white or blue in later stages. These are the most common symptoms and the list goes on.
If you believe your dog has bloat they should be seen immediately. Simethicone products like gas-x may help while you take him into the vet. Simethicone dosages can be found here:
You can read more on bloat here.
If your dog eliminated recently then constipation should not be causing a distended stomach. Parasites can sometimes cause a distended stomach and lead to a loss of appetite as well though we usually see abnormal stools with parasites.
If your dog may have ingested a bone or sharp pointed object, it may have punctured the gastrointestinal tract. You can read about this here:
Cushing disease can cause a bloated stomach as well. You can read about this condition here:
Only you can see exactly how sick your dog is and make the determination on whether an ER visit is necessary, but I can give you the possible causes to help you make the decision. If the ingestion of items from a dumpster area may have included bones or other sharp objects then I would have him see sooner rather than waiting at all. They could do diagnostic imaging to determine what the cause is.
Let me know if finances are an issue as there are some places that give a free office visit.
I hope this information is helpful to you. If you would like any additional information or have more questions please don’t hesitate to press the reply to expert or continue conversation button so I can address any issues you still have . If you do find this helpful, please take this opportunity to rate my answer positively so I am compensated for my time.