Hi malamute,
That "thing" you are seeing come out of your dog's anus...is her own rectum. Yes...that is as serious as it sounds. You should really take your dog to a different veterinarian to be evaluated for an impaction. It is not uncommon for puppies to have such a high load of intestinal parasites, that they become impacted with them and then prolapse their rectums (push their large intestine out of their own anus), trying to defecate out the impacted worms. You do not want this to happen.
You need to see a vet who will evaluate your dog for this possibility and help her...before she prolapses her rectum.
I really hope that this information helps you out, and that your puppy gets better soon. Please let me know if I can be of further assistance.
Dr. K
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Thanks,
Dr. K