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

Abstract

ObjectivesThis 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.MethodsA 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.ResultsA 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 relevanceThis 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.

Keywords: Cobalamin; chronic diarrhoea; chronic enteropathy; chronic vomiting; hypercobalaminaemia; hypocobalaminaemia; vitamin B12.

Figure 1

Box plot representing the age distribution between the three groups (hypocobalaminaemia, normocobalaminaemia and hypercobalaminaemia)

Figure 2

Bar chart representing the body condition score distribution between the three groups (hypocobalaminaemia, normocobalaminaemia and hypercobalaminaemia)

Figure 3

Bar chart representing the percentage (%) of cats that display the three main clinical signs identified: chronic vomiting (v+), hyporexia and chronic diarrhoea (d+)

Figure 4

Bar chart representing the percentage of cats with the diagnosis of LGITL, LPE, EE and presumed CE, among the three groups: hypocobalaminaemia, normocobalaminaemia and hypercobalaminaemia. Most cats diagnosed with LGITL have hypocobalaminaemia, while most cats with presumed CE have hypercobalaminaemia. CE = chronic enteropathy; EE = eosinophilic enteritis; LGITL = low-grade intestinal T-cell lymphoma; LPE = lymphoplasmacytic enteritis

Figure 5

Stacked bar representing the proportion of cats in the hypocobalaminaemic, hypercobalaminaemic and normocobalaminaemic group with anaemia, leucocytosis, neutrophilia, monocytosis, hypoalbuminaemia, increased alkaline phosphatase and hypercholesterolaemia. Cats with normal values are shown in blue, those with mild values in red, those with moderate values in yellow and those with severely abnormal values in green

Figure 6

Kaplan–Meier curve depicting survival time for 216 cats at the time of cobalamin measurement

Figure 7

Kaplan–Meier curve depicting survival time for 216 cats at the time of cobalamin measurement