Three years?!!
And you are getting around to it now?
You have left out critical information:
Age/breed/size/age at neutering/general health/weight(fat/thin)?
Blood & mucus could certainly be coming from the intestines. But the large intestine (colon), not the small. Causes could include:
Punctures – does the dog eat/have access to anything that could fragment? Bones? Sticks? Pencils?
Food allergies – for instance dogs develop gluten intolerance at about the same approximate frequency as humans.
Obesity – especially together with a poor diet.
Vitamin deficiencies – can cause bleeding, anemia and more.
Canine shingles manifests as acute colitis.
Stress – no kidding
Improper diet: For instance – some people feed their dogs garlic in quantity in the belief that it helps the dog to repel fleas..
Try, in no particular order but *one thing at a time*:
1. An elimination diet: Using either home-cooked or high-end prescription foods, remove certain common bulk fillers found in commercial foods – corn gluten meal, wheat and other items no wolf would normally ever eat. There are quite a number of legitimate websites for this. And equally many bad ones. Look at the Cornell or University of Pennsylvania Vet websites for a start.
2. Add natural fiber to her diet.
3. *WITH YOUR VET’s KNOWLEDGE: Try L-Lysine as a supplement.
4. Mild Diabetes can manifest by internal bleeding.
Most likely this will be able to be treated with diet.
