CBL and gastrointestinal disease: In cats with Cbl deficiency and signs of gastrointestinal disease, 3 IM injections of 300 μg OH‐Cbl given every 2 weeks, significantly increased serum Cbl concentrations to supranormal values at t1, followed by a significant decrease to a median Cbl concentration within the reference range 4 weeks after the 4th injection.