Why is my 3-month-old puppy's stool black and yellow after vaccines?
Take a stool sample in to your vet to be examined. If he is acting normally, playful, eating, has good energy, etc, I don't think you need to be too concerned, but do take him in and bring a stool sample with you. Your vet may recommend deworming him if it hasn't been done within the last 2 weeks. I doubt its related to his vaccines. Vaccine reactions typically occur within hours of the vaccine being given, and it sounds like there was enough of a delay that its not likely the cause. In terms of you "felt something," when your hand was on his stomach, I suspect you were feeling gas moving through the GI tract, which is normal. If he was painful at the time, or he seems distressed, is vomiting, etc, take him in ASAP.
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Updated on September 23rd, 2025