can it be a blockage?

Question
My Chihuahua has had loose stools with mucus and a little blood for approximately 3 weeks.She has also vomited occasionally during this time. She has been to the vet and is on amoxicillin, amforal, and metocloprimide.  On the weekend she vomitted quite a bit so we took her in to the on call vet. He thought she might have a blockage and wanted to do surgery right away. However my dog has not been acting real sick she is less active but is willing to eat, drink, greet me when I come home. So we decided not to have the surgery and just watch her for a few days. Now yesterday she had a normal formed bowel movement. (1st one in 3 weeks) Can she have a normal bowel movement if there is a blockage?

Answer
Most likely, no. However, dogs do amazing things.
Stool with mucous sounds more like a serious food intolerance, especially with vomiting.
If she finally had a normal bowel movement the chances are she either vomiting out the offending object or it has passed down into the large intestine finally and she was able to pass a normal stool. Dogs with blockages or partial blockages have either severe diarrhea or no stool at all and they vomit and vomit because they are toxic.
It is your decision to watch for a few days. I would put her on a bland diet of boiled rice and turkey burger for about three days then slowly start adding back in her food.
If she has a mucousy stool again then you need to re-access her diet.