It's unlikely the hot dogs would cause him to have blood in his stool. You should take a stool sample in to your vet and have them check for internal parasites which would be the most common cause of blood in the stool for puppies. If he is depressed, vomiting or has watery stool it may also be parvo so be on the alert for that too. That would require immediate vet attention.
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Holistic Wellness Care
