Folate deficiency

From Dog

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[1] and essential for RNA and DNA processes.

Normal levels of folate in dogs is 10 - 12 μg/L[2] 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[3][4].

Clinical signs associated with folate deficiency in dogs is primarily megaloblastic anemia.

A breed predispositions for decreased folate concentration has been reported in the Golden Retriever and Boxer[5].

Folate deficiency is commonly seen in dogs with pancreatic exocrine insufficiency[6], chronic renal disease[7], but can also be observed with disease of the proximal small intestine, methotrexate administration[8], 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[9].

References

  1. Sysel AM et al (2012) Serum folate: a pharmacodynamic biomarker of intracellular nitrosylcobalamin activity following intravenous administration in dogs. Anticancer Res 32(10):4307-4312
  2. Frias R et al (2012) Small intestinal permeability and serum folate and cobalamin absorption after surgical construction of permanent jejunal fistulas in laboratory beagle dogs. Comp Med 60(5):369-373
  3. Berghoff N et al (2007) Gastroenteropathy in Norwegian Lundehunds. Compend Contin Educ Vet 29(8):456-465
  4. Merck Veterinary Manual
  5. Dandrieux JR et al (2013) Canine breed predispositions for marked hypocobalaminaemia or decreased folate concentration assessed by a laboratory survey. J Small Anim Pract 54(3):143-148
  6. Dossin O (2011) Laboratory tests for diagnosis of gastrointestinal and pancreatic diseases. Top Companion Anim Med 26(2):86-97
  7. Galler A et al (2012) Blood vitamin levels in dogs with chronic kidney disease. Vet J 192(2):226-231
  8. Lewis DH et al (2010) Use of calcium folinate in the management of accidental methotrexate ingestion in two dogs. J Am Vet Med Assoc 237(12):1450-1454
  9. Batt RM et al (1991) Validation of a radioassay for the determination of serum folate and cobalamin concentrations in dogs. J Small Anim Pract 32:221–224