Suspected acquired hypocobalaminaemic encephalopathy in a cat: resolution of encephalopathic signs and MRI lesions subsequent to cobalamin supplementation.

UNLABELLED: PRESENTING SIGNS AND INITIAL INVESTIGATIONS: An 8-year-old female spayed British shorthair cat was presented with a history of waxing and waning neurological signs. Neuroanatomical localisation was consistent with a diffuse forebrain disease. Blood ammonia concentration was increased. Abdominal ultrasonography and a bile acid stimulation test were normal. Magnetic resonance imaging (MRI) revealed hyperintense, bilaterally symmetrical, diffuse lesions on T2-weighted sequences, predominantly, but not exclusively, affecting the grey matter. Serum cobalamin (vitamin B12) concentration was low. Hypocobalaminaemia resulting in a urea cycle abnormality was considered a likely cause of the hyperammonaemia.

TREATMENT: Daily cobalamin injections resulted in a rapid clinical improvement. Eight weeks into treatment neurological examination was unremarkable and there was complete resolution of the MRI lesions.

CLINICAL

IMPORTANCE

This is the first reported case of acquired feline hypocobalaminaemia resulting in an encephalopathy. Additionally, this case is unique in describing reversible brain MRI abnormalities in a cobalamin-deficient companion animal.