Prevalence of hypocobalaminaemia and hypercobalaminaemia in a referral population of cats in the UK and its relevance to clinical presentation, diagnosis and prognosis

Abstract

Objectives This study aimed to assess the prevalence of hypocobalaminaemia (B12 <400 pg/ml) and hypercobalaminaemia (B12 >1000 pg/ml), describe the clinicopathological abnormalities and the diagnostic imaging findings in a referral population of cats in the UK, and identify the underlying disease processes associated with both conditions. Methods A retrospective study of cats that had their serum cobalamin concentration assessed between December 2016 and December 2023 at a single referral hospital; 216 cats were included. Patient outcome was established from the clinical records. Results A total of 76 (35%) cats had hypocobalaminaemia and 67 (31%) cats had hypercobalaminaemia. The most common diagnoses were chronic enteropathy (CE) in 39/76 (51%) hypocobalaminaemic cats and 39/67 (58%) hypercobalaminaemic cats ( P = 0.001), and high-grade lymphoma in 14/76 (18%) hypocobalaminaemic cats and 11/67 (16%) hypercobalaminaemic cats ( P = 0.438). The most common clinical signs were chronic vomiting in 36/76 (47%) hypocobalaminaemic cats and 24/67 (36%) hypercobalaminaemic cats ( P = 0.005), hyporexia in 40/76 (53%) hypocobalaminaemic cats and 21/67 (31%) hypercobalaminaemic cats ( P <0.001), and chronic diarrhoea in 12/76 (16%) hypocobalaminaemic cats and 21/67 (31%) hypercobalaminaemic cats ( P = 0.001). The most common abnormalities identified on abdominal ultrasound were lymphadenomegaly and thickened intestines in 49/76 (64%) hypocobalaminaemic cats and 28/67 (42%) hypercobalaminaemic cats ( P = 0.0025). Median survival time was 274 days in the hypocobalaminaemic group and 711 days in the hypercobalaminaemic group ( P = 0.001). The hypocobalaminaemic cats exhibited significantly reduced survival time compared with hypercobalaminaemic cats (odds ratio 2.4 vs 0.4, respectively) ( P <0.001). Conclusions and relevance This study suggests that cobalamin has limited diagnostic utility in differentiating between underlying disease processes; chronic diarrhoea and CE are more common in hypercobalaminaemic cats in contrast with the previous literature. Hypocobalaminaemia is associated with reduced survival in this cohort of cats; therefore, early cobalamin supplementation is recommended.