Abstract
A 6-month-old Holstein heifer that was nonresponsive to medical treatment was evaluated for chronic respiratory disease. Complete blood count and serum chemistry revealed neutrophilic leukocytosis and low globulin levels. Assays for bovine leukemia virus, bovine virus diarrhea, and bovine leukocyte adhesion deficiency were negative. Serum globulin subclass assays revealed transient low concentrations of immunoglobulin (Ig) G1 and IgA, persistent low IgG2, and subnormal IgM. Vaccination with 2 doses of multiple, inactived viruses induced seroconversion for most viruses. Flow cytometric analysis of blood lymphocyte subpopulation demonstrated an increase in CD5+ B-cells. Blood lymphocyte proliferation and neutrophil function tests were normal. Results of immunologic assays indicated IgG2 deficiency with transient hypogammaglobulinemia.
