“…Recurrent fevers and opportunistic infections, particularly of the respiratory tract, are the hallmarks of impaired immune function in all species and ages, and the presence of either should prompt veterinarians to evaluate for an underlying immunodeficiency (Crisman & Scarratt, 2008; Riggs, 1987; Smith & Cunningham‐Rundles, ). In both human and veterinary medicine, serum IgG concentration is measured as a screening test for humoral immunity (Crisman & Scarratt, 2008; Felippe, 2018; Notarangelo, 2010). If serum IgG concentrations are found to be low, further and repeated immunologic evaluation is indicated.…”