Pernicious anemia occurs more commonly in people who already have diseases that are linked to immune-system abnormalities, such as Graves disease, hypothyroidism (under-functioning thyroid gland), thyroiditis (inflammation of the thyroid), vitiligo, and Addison's disease (adrenocortical insufficiency)
This isn't an enteric coating applied after the fact
While it has been in research for over 20 years, it has recently gained a second life thanks to the massive public interest in peptide therapy and the rise of GLP-1 medications.
Castelli V, Lavanco G, Dmico C, Feo S, Triangli G, Kuchar M, et al
Therefore, vitamin B12 supplements are recommended for dogs with digestive ailments, including long-term diarrhea or chronic colitis, inflammatory bowel disease (IBD), and exocrine pancreatic insufficiency (EPI)