Get Your Dog Care Questions Answered by Experts
You didn't indicate if she is eating, drinking and urinating. Since she has no issues apart from a hard abdomen and appears bloated, I will assume she is eating, drinking and urinating normally.
It would be useful if you could take her temperature and do a quick check for circulatory problems.
You can take the temperature using a human thermometer. Lubricate the end and put it in the rectum 1-2 inches using gentle pressure. Remove it after a minute. Normal temperature for cats and dogs is 101 - 102.5. 103 is a low grade fever and 104-106 is the common range for fevers.
Look at the gums. They should be pink, not white, blue or bright red. Press on the gums behind an upper canine tooth using your finger. It will blanch white with the pressure and be white when you first remove your finger. It should return to pink in 2 seconds or less. If it takes more than 3 seconds, it indicates poor circulation, which can be caused by dehydration or heart problems.
In general, dogs that are eating, drinking, urinating, defecating, not vomiting and acting normally, are not in immediate danger. If, in addition to the above, the temperature, gum color and capillary refill time (CRT) are normal, you can probably wait until regular vet hours tomorrow (Monday).
The cause of the bloated appearance and hard abdomen will require a hands on exam and probably some diagnostic testing. Bloat refers to distension of the stomach with air with or without torsion. Dogs with this condition do not act, eat, drink, urinate and defecate normally Tumors and blood or fluid accumulation in the abdomen can produce a distended, hard abdomen. These can cause discomfort even if pain on palpation is not severe.
As always, we can offer general information by computer, but can not perform the physical exam and other tests necessary to diagnose. If you are or become more concerned or if the signs your dog is showing get worse, it makes sense to get to a vet sooner.
Because the signs you mention are not very specific for any syndrome, there is nothing I can recommend to try at home.
Let me know if you have follow up questions.