Correlation between serum cobalamin concentration, histopathologic changes, and outcome in cats with chronic...

Hypocobalaminemia is commonly used as a surrogate marker for distal small intestinal disease and may prompt ileal biopsy sample collection in cats. However, the correlation between serum cobalamin concentration and small intestinal histologic lesions has not been established in cats.

Determine the correlation between serum cobalamin and folate concentrations, histologic lesions, and clinical outcomes in cats with chronic enteropathy (CE).

Formalin-fixed, paraffin-embedded duodenal and ileal samples from 73 client-owned cats with CE.

Retrospective study. Tissue archives were systematically searched for cases of CE with recorded serum cobalamin concentrations. A single pathologist blinded to clinicopathological data scored duodenal and ileal biopsy samples using a modified World Small Animal Veterinary Association (WSAVA) scoring system. A modified Feline Chronic Enteropathy Activity Index (FCEAI) was used for outcome assessment.

Seventy-three cases were included. Serum cobalamin concentrations showed a moderate negative correlation with total ileal WSAVA and cellular infiltrate scores (r = -0.44, P < .001 and r = -0.50, P < .001). Serum folate concentration did not show any significant correlations. Out of 51 cats with hypocobalaminemia, 50 had histologic lesions in either the ileum, the duodenum, or both, and 5 had histologic lesions confined to the duodenum with no ileal involvement. Serum cobalamin concentration was not associated with FCEAI or outcome.

Serum cobalamin concentrations in cats with CE are negatively correlated with histopathologic severity, particularly cellular infiltration in both the duodenum and ileum. However, hypocobalaminemia may not reliably predict the presence of ileal lesions.