Folic acid (Vitamin B9) is an important vitamin essential for cell replication and growth.
Cobalamin and folate are interdependent co-factors of the methionine synthase pathway and essential for RNA and DNA processes.
Normal levels of folate in dogs is 10 - 12 μg/L and daily requirements are about 4 - 6 mg in dietary sources.
Sources of folic acid in the diet include yeast, liver, kidney, and green vegetables, although it can also be formed by microbes. Folic acid is stored in the liver but not as avidly as vitamin B12. Because folic acid is destroyed by catabolic processes every day, serum levels decrease rapidly in the presence of deficient diets. Absorption of folic acid is not as sensitive as that of vitamin B12, although jejunal pathology can result in folate deficiency.
Clinical signs associated with folate deficiency in dogs is primarily megaloblastic anemia.
Folate deficiency is commonly seen in dogs with pancreatic exocrine insufficiency, chronic renal disease, but can also be observed with disease of the proximal small intestine, methotrexate administration, potentiated sulfa drugs, some anticonvulsants (eg, primidone and phenytoin) and hepatitis.
Hypocobalaminemia may also be observed in cases where lower small intestinal organs are affected.
With diffuse small intestinal mucosal disease, both cobalamin and folate concentrations may be decreased. Small intestinal bacterial overgrowth in dogs may also cause increased serum folate concentrations with or without decreased serum cobalamin concentrations.
A folate radioassay test is available provides information on the functional ability of the canine small intestine, and more specifically, on the absorptive efficiency of the jejunal and ileal enterocytes.
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- Merck Veterinary Manual
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