Yes, the chicken strip could be causing the bloody diarrhea. There are two frequent diagnoses that involve bloody diarrhea after "human" food consumption. One is HGE (hemorrhagic gastroenteritis) and the other is pancreatitis.
Usually practicioners start with bloodwork, fecal analysis (to ensure that the intestines are clear of intestinal parasites, bacteria such as clostridium and protazoa), some will do a parvo snap test to make sure the case of bloody diarrhea is not due to the canine parvo virus (although there is a low incident of vaccinated dogs getting it--it sometimes happens), an Idexx snap test that checks for a pancreas-specific enzyme to rule out or determine pancreatitis, IV catheterization and IV fluids to rehydrate the pet since volumes of fluids are being lost, an IV antibiotic such as metronidazole and anti-vomiting medications if the pet having vomiting (this can accompany both HGE and pancreatitis). Treatment can run 24 hours or more. The average we see at our hospital is 3 days. Afterwards, we send the patient home on oral antibiotics (after they're eating and drinking normally with no occurance of blood in the stool) such as metronidazole and a food gentle on the stomach (see further below).
Here is an article on pancreatitis:
and one on HGE:
The best thing for your pet at this time is to take him to your vet and have a few diagnostic tests run to see what your pet is afflicted with. Even pets that have had routine "human foods" can randomly come down with both HGE and pancreatitis. Small dogs are frequently affected by both more than larger dogs, but there are occurances of larger breeds too.
Once the determination has been made, the best thing to do is skip sharing most human foods with any pets (items such as boiled rice, boiled chicken breast with no skin, carrots, peas, etc are acceptable--check with your veterinarian if you're unsure). It's usually high fat foods that cause the most problem, but its best to just skip feeding all food to make sure there are no more occurances of this in your household. Foods such as boiled rice and boiled skinless chicken breast will be safe foods for when your pet comes home instead of feeding normal dog food--and then slowly moving over from the rice and chicken to the regular dog food. Hill's I/D is a good commerical food that will do the same if you elect to not cook for your pet. The idea behind both of these foods is to have something gentle on the stomach after this type of incident.
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