Friend, when we see blood with diarrhea it is a sign of inflammation in the colon (large intestines). This can be caused by many different medical conditions. It will be difficult for me to determine the exact underlying cause without a hands on examination and some testing. But, in a puppy common causes are: Dietary indiscretion, ingestion of a foreign body, infections, parasites, etc.In this case, I would strongly recommend having your family veterinarian examine a stool sample as initial screening test. In the meantime this is what you can do:1- Do not give things like Pepto Bismol or imodium. You see, stopping the diarrhea with medication can make things worst if this is related to an infection or ingestion of a foreign body. In addition, pepto bismol will make the bleeding
worst. 2- No food or water for 8-12 hours, need to give his gastrointestinal tract time to rest. Then, offer small amount of water followed by a diet of rice (75%) and boiled boneless chicken
or ground beef (25%) until the stool is back to normal then wean him back into his regular diet. Keep him indoors in a cool room and no exercise when fasting. 3- Supplement with a probiotic (fortiflora), these are friendly bacteria that help with regularity and inflammation. You can buy this over the counter in any pet store. 4- Follow up with your family veterinarian for a hands on examination and fecal analysis. In addition, discuss with your vet about starting him on a medication called Metronidazole, this is an antibiotic that will help with the inflammation. If cost is a concern look into your local ASPCA or Shelter where they often offer veterinary services at a lower cost. My goal is to provide you with excellent service - I hope I've provided the information you were seeking, if you feel you have received anything less, please reply back as I am happy to address follow-up questions. Kindly rate me when you are done.