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Evaluation of a commercially available immunoassay for assessing adequacy of passive transfer in calves

Maisie E. Dawes DVM1, Jeff W. Tyler DVM, PhD, DACVIM2, Douglas Hostetler DVM, MS3, Jeff Lakritz DVM, PhD, DACVIM4, and Ronald Tessman DVM5
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  • 1 Department of Veterinary Medicine and Surgery, College of Veterinary Medicine, University of Missouri, Columbia, MO 65211.
  • | 2 Department of Veterinary Medicine and Surgery, College of Veterinary Medicine, University of Missouri, Columbia, MO 65211.
  • | 3 Department of Veterinary Medicine and Surgery, College of Veterinary Medicine, University of Missouri, Columbia, MO 65211.
  • | 4 Department of Veterinary Medicine and Surgery, College of Veterinary Medicine, University of Missouri, Columbia, MO 65211.
  • | 5 Department of Veterinary Medicine and Surgery, College of Veterinary Medicine, University of Missouri, Columbia, MO 65211.

Abstract

Objective—To evaluate diagnostic utility of a commercially available immunoassay for assessing adequacy of passive transfer of immunity in neonatal calves.

Design—Prospective study.

Animals—123 calves.

Procedure—Blood and serum samples were obtained from the calves prior to 2 weeks of age. The immunoassay was performed, along with refractometry and an 18% sodium sulfite turbidity test. Serum IgG concentration was determined with a radial immunodiffusion assay. Sensitivity and specificity of the immunoassay, refractometry, and the sodium sulfite test were calculated by comparing results with results of the radial immunodiffusion assay.

Results—Sensitivity and specificity of the blood IgG immunoassay were 0.93 and 0.88, respectively, compared with 1.00 and 0.53 for the sodium sulfite test. For refractometry, sensitivity and specificity were 0.71 and 0.83, respectively, when a serum total solids concentration of 5.2 g/dl was used as the cutoff between positive and negative test results.

Conclusions and Clinical Relevance—Results suggest that the immunoassayperforms well in detecting calves with inadequate passive transfer of immunity. (J Am Vet Med Assoc 2002;220:791–793)