Serum concentrations of IgG, IgA, and IgM in retired racing Greyhound dogs

Background Greyhound dogs have significant physiologic, hematologic, and biochemical differences when compared with other breeds, including significantly lower serum globulin concentration owing to decreases in the alpha- and beta-globulin fractions. The specific proteins that account for differences in globulin concentrations are not known, but IgA and IgM, both beta-globulins, are potential candidates. Objectives The aims of this study were to measure serum IgG, IgA, and IgM in clinically healthy retired racing Greyhounds and compare the results with those of age- and sex-matched non-Greyhound dogs. Methods Study animals included 25 Greyhound and 20 non-Greyhound dogs. Total protein, albumin, and total globulin concentrations were determined. IgG, IgA, and IgM concentrations were measured using a commercially available radial immunodiffusion kit. The Student t-test assuming equal variances was used to compare concentrations of immunoglobulins between groups. Results Serum concentrations of IgA and IgM in Greyhounds (IgA=49 +/- 20 mg/dL; IgM=132 +/- 47 mg/dL) were significantly lower than concentrations in non-Greyound dogs (IgA=70 +/- 39 mg/dL; Ig M=212 +/- 78 mg/dL). Concentrations of IgG did not differ between groups. Conclusions Mean serum IgA and IgM concentrations in Greyhounds were lower than those in non-Greyhound dogs. This may contribute to low serum concentrations of beta-globulins in Greyhounds. Specific reference intervals are recommended for Greyhounds to avoid possible misdiagnosis of IgA or IgM deficiency.