Friend, when we see bloody diarrhea this is caused by inflammation in the colon. I am sure this is very scary for you seeing him bleed. But, depending on the underlying cause will depend on the prognosis. You see, 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, common causes are: Dietary indiscretion, HGE, ingestion of a foreign body, infections, or even part of a systemic disease to name a few causes. If you are noticing his gums more red than usual I would have him checked by ER veterinarian, important to rule out HGE (hemorrhagic gastroenteritis) which could be fatal. I don't want to scare you, but, I would prefer to err on the side of caution. If you do not have access to ER veterinarian this is what you can do until he is seen by family veterinarian:
1- Do not give things like Pepto Bismol or Imodium. Start him on Pepcid AC (famotidine) 10mg every 12 hours. You can buy Pepcid AC over the counter in any pharmacy.
2- No food or water for 3-4 hours to control the vomiting need to give his gastrointestinal tract time to rest. Then, offer a small amount of water, wait a half hour if no vomiting continue to give water every hour or so. Leave him without food for 8-12 hours, then offer 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, these are friendly bacteria that help with regularity. You can buy this over the counter in any pet store.
4- Follow up with your family veterinarian for a hands on examination.
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