Welcome! My name is***** am a 2003 graduate, and currently a Medical Director of a veterinary hospital.
I am sorry to hear about this concern for Ruby.
Blood int he stools, at this age, could be associated with:
1. Intestinal parasites (worms, even if been dewormed), microscopic parasites like giardia or coccidia.
2. STress induced
3. Recent diet change or having started new dog treats
4. Recent vaccines
5. Viral infection
So, if eating and drinking good and still playful, those are great positives. However, if persisting, it needs to be evaluated by a vet as soon as possible.
Also, even if a fecal test has been done, I would strongly recommend it get repeated as soon as possible.
Bring in a fresh poop sample to the veterinarian. Ideally, within a few hours. Request that it be sent “OUT” to the laboratory instead of being looked at in the hospital (more accurate that way). We are not interested in only worm eggs, but also checking for the very common microscopic bugs like giardia and coccidia. These types of parasites will not be cured with over-the-counter dewormers. Giardia can also be difficult to identify on routine fecal tests, so ask your vet if they always add a “giardia elisa” to the fecal test. Here is more detailed information about fecal testing:Fecal Testing
Ah..just read that you did do a diet change. Could be the cause but let's not assume it. Good Luck!
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