Functional indicators of folate status in cats and dogs: use of metabolic markers to guide clinical decision-making regarding folate deficiency

Abstract

Background: Alterations to folate status are widely recognised in cats and dogs with gastrointestinal disease, however the clinical significance of hypofolataemia in small animals remains unclear. Functional indicators could be used to identify small animals that have true whole-body folate deficiencies, which would help to expand the body of knowledge available relating to folate deficiency in cats and dogs. The author proposes that plasma FIGLU measurement shows promise as a functional indicator of folate deficiency in cats and dogs.

Objectives:

1) To develop and analytically validate a liquid chromatography tandem mass spectrometry (LC-MS/MS) method for the quantitation of FIGLU in feline and canine plasma.

2) To report ranges of plasma FIGLU in clinically normal cats and dogs.

3) To assess for a correlation between serum folate and plasma FIGLU concentrations.

Methods: An LC-MS/MS method for the quantitation of plasma FIGLU was developed and analytically validated with respect to linearity, accuracy, precision, recovery and dilution integrity. Plasma FIGLU and serum folate were measured in 11 dogs and 10 cats that were clinically normal. Statistical analysis was performed to assess for correlations between plasma FIGLU and serum folate concentrations.

Results: All within-run and between-run accuracy and precision values for measurement of plasma FIGLU met the predefined validation requirements. Plasma FIGLU concentrations ranged from 4.5 to 21.0 ng/mL in dogs, and 9.1 to 57.0 ng/mL in cats. There was no evidence of a correlation between serum folate and plasma FIGLU concentrations in clinically normal cats and dogs.

Conclusions: This study demonstrated that the amounts of FIGLU present endogenously in the plasma of clinically normal cats and dogs is high enough to be quantifiable via LC-MS/MS techniques. Spot plasma FIGLU measurement therefore shows promise as a practical research tool and a potential functional indicator of folate deficiency in cats and dogs.