title: Use of Fourier-transform infrared spectroscopy to quantify immunoglobulin G concentration and an analysis of the effect of signalment on levels in canine serum.
abstract: Deficiency in immunoglobulin G (IgG) is associated with an increased susceptibility to infections in humans and animals, and changes in IgG levels occur in many disease states. In companion animals, failure of transfer of passive immunity is uncommonly diagnosed but mortality rates in puppies are high and more than 30% of these deaths are secondary to septicemia. Currently, radial immunodiffusion (RID) and enzyme-linked immunosorbent assays are the most commonly used methods for quantitative measurement of IgG in dogs. In this study, a Fourier-transform infrared spectroscopy (FTIR) assay for canine serum IgG was developed and compared to the RID assay as the reference standard. Basic signalment data and health status of the dogs were also analyzed to determine if they correlated with serum IgG concentrations based on RID results. Serum samples were collected from 207 dogs during routine hematological evaluation, and IgG concentrations determined by RID. The FTIR assay was developed using partial least squares regression analysis and its performance evaluated using RID assay as the reference test. The concordance correlation coefficient was 0.91 for the calibration model data set and 0.85 for the prediction set. A Bland-Altman plot showed a mean difference of -89 mg/dL and no systematic bias. The modified mean coefficient of variation (CV) for RID was 6.67%, and for FTIR was 18.76%. The mean serum IgG concentration using RID was 1943 ± 880 mg/dL based on the 193 dogs with complete signalment and health data. When age class, gender, breed size and disease status were analyzed by multivariable ANOVA, dogs < 2 years of age (p = 0.0004) and those classified as diseased (p = 0.03) were found to have significantly lower IgG concentrations than older and healthy dogs, respectively.
authors.affiliation: Department of Companion Animals, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, PE, Canada C1A 4P3.
authors.forename: A
authors.initials: A
authors.lastname: Seigneur
authors.affiliation: Department of Health Management, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, PE, Canada C1A 4P3.
authors.forename: S
authors.initials: S
authors.lastname: Hou
authors.affiliation: National Research Council of Canada, Medical Devices, Winnipeg, MB, Canada R3B 1Y6.
authors.forename: R A
authors.initials: RA
authors.lastname: Shaw
authors.affiliation: Department of Health Management, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, PE, Canada C1A 4P3.
authors.forename: Jt
authors.initials: J
authors.lastname: McClure
authors.affiliation: Department of Companion Animals, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, PE, Canada C1A 4P3.
authors.forename: H
authors.initials: H
authors.lastname: Gelens
authors.affiliation: Department of Health Management, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, PE, Canada C1A 4P3; Institute of Veterinary, Animal & Biomedical Sciences, Massey University, Palmerston North 4442, New Zealand. Electronic address: C.B.Riley@massey.ac.nz.
authors.forename: C B
authors.initials: CB
authors.lastname: Riley
mesh_terms: D000367:Age Factors; D000818:Animals; D002138:Calibration; D004283:Dog Diseases / Q000097:blood / Q000276:immunology; D004285:Dogs / Q000097:blood* / Q000276:immunology; D005260:Female; D007116:Immunization, Passive / Q000662:veterinary; D005779:Immunodiffusion / Q000662:veterinary; D007074:Immunoglobulin G / Q000097:blood*; D008297:Male; D015203:Reproducibility of Results; D017550:Spectroscopy, Fourier Transform Infrared / Q000662:veterinary*
chemical_list: D007074:Immunoglobulin G
keywords: Dog; Failure of transfer of passive immunity; Fourier-transformed infrared spectroscopy; Immunoglobulin G; Partial least squares; Radial immunodiffusion