Cobalamin deficiency associated with methylmalonic acidemia in a cat

A 9-month-old sexually intact male longhair cat was examined because of lethargy, anorexia, cold intolerance, and failure to thrive since acquisition at an early age. Clinical signs of disease were less pronounced when the cat was fed a low-protein diet. Anemia, hypoglycemia, low total CO2 content, and hyperammonemia were detected. The cat was euthanatized. Urine obtained immediately before euthanasia contained a large amount of methylmalonic acid. Total serum cobalamin concentration was low. Hepatic methylmalonic-CoA mutase activity, with and without the addition of coenzyme adenosylcobalamin, was consistent with a cobalamin deficiency. Methylmalonic acidemia secondary to a putative defect in cobalamin absorption was diagnosed.