Good Morning and welcome! I am Dr. Loretta, a licensed veterinarian and I am happy to answer your question.
It appears that your guy ingested something that did not agree with him. This can cause a digestive disturbance causing vomiting and diarrhea. This diarrhea will cause irritation to the very sensitive rectal mucosa causing blood vessels to break and bleed. This is not serious and will resolve once the disturbance is resolved. The treatment for this is as follows:
Fast your guy for 12-24 hrs to allow the digestive tract to calm down and heal.
Give Pepcid AC or Famotidine at 0.5 mg per pound every 8 hrs. That can be purchased over the counter at the pharmacy.
Give only small amounts of water during the fast or ice cubes
After the fast, feed rice and boiled chicken (2/1)
If the vomiting and diarrhea have resolved, then wean back him onto regular food. If the vomiting persists especially during the fast, take your dog to your vet for an exam and lab work to determine the cause for this. This is extremely important since this can cause dehydration or other more serious concerns such as an intestinal obstruction. In most cases such as this, this treatment is curative.
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