I am very sorry to hear about her loose stools with mucous and blood.
Of course anyone would be concerned about blood in the stool. The fresher the blood appears the closer the source is to her rectum.
The important factor in all of this is how she feels otherwise. If she is acting normal and seems to feel great otherwise then that is a good sign. Blood and mucous are signs of colonic irritation, and it is possible that bone chip fragments and eating a rich, unusual food are behind this.
But there is a condition in dogs called hemorrhagic gastroenteritis. These dogs have profuse dark, jelly-clot like, bloody diarrhea. They are very sick dogs and get dehydrated quickly so they need immediate care. Thus if she becomes lethargic and/or begins vomiting an emergency veterinary visit is best.
Colitis or inflammation of the large intestine, can be due to stress, a change in diet (bones), parasites, a viral or bacterial infection, inflammatory bowel disease or even a food allergy. Rarely a mass in the colon can be the cause, or exposure to anticoagulant rodenticides. Infected anal glands can cause a bloody discharge too, so if she isn't improving her anal glands should be checked.
A raw, irritated colon can take a few days to heal from any insult, and if the bone fragments are still being passed it can take a little longer. The bleeding should clear completely with treatment and as the fragments pass over the next 2 to 3 days. If not she should be checked by her regular veterinarian and her anal glands should be checked too. Well worth checking at least a couple fresh stool samples too as parasite eggs/cysts are shed intermittently and they may be picked up on the second sample or third test even if the first is negative.
Since she still feels well now though we can try some things at home.
If her appetite is off and her stomach is gurgling she may have some stomach upset and reflux that can go along with bloody stools.
To try and settle her stomach today you can give either:
1) Pepcid-ac (famotidine) at a dose of one 10mg tablet per 20 to 40 pounds of body weight every 12 hours.
2) Prilosec (omeprazole) at a dose of one half of a 20mg tablet per 20 to 40 pounds of body weight every 24 hours.
These will reduce stomach acid and should help if this is related to simple nausea and gastrointestinal irritation. They can be given for several days.
If her appetite is fine you can skip this step.
If she has a tense painful abdomen, becomes very lethargic, begins vomiting or runs a fever greater than 103.5F then she really must be seen by a veterinarian as soon as possible. Make sure to take a fresh stool sample with you when you go.
If she is not vomiting I would not fast her with a history of eating bones. It's best to use fiber to help the bone pieces pass and a bland diet to soothe her intestines. An empty gastrointestinal tract contracting on bone splinters can make things worse.
Start a bland diet mix of 1/3 boiled, lean hamburger (or boiled, white skinless chicken), all fats and juices drained off, mixed with 2/3 boiled, plain white rice. Feed several small meals a day. Add 2 tablespoon of canned pumpkin (not pie filling, just pumpkin) to each meal as fiber helps soothe an irritated colon. I recommend adding probiotics like Fortiflora, Proviable or Benebac to her meals daily to re-establish normal gut bacteria levels too.
Once she feels better (no bloody diarrhea for 48 hours) start mixing in her regular dog food very slowly. Less bland more regular with each day. It should take a week or so to convert her back.
If your pup is vomiting and feeling poorly though it would be best that she see a veterinarian now as anything you give orally will just come back up worsening her dehydration.
Best of luck with your pup, please let me know if you have any further questions.