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 α- and β-globulin fractions. The specific proteins that account for differences in globulin concentrations are not known, but IgA and IgM, both β-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 β-globulins in Greyhounds. Specific reference intervals are recommended for Greyhounds to avoid possible misdiagnosis of IgA or IgM deficiency.