Quality control validation, application of sigma metrics, and performance comparison between two biochemistry analyzers in a commercial veterinary laboratory, Alison J Farr and Kathleen P Freeman, J Vet Diagn Invest. September 2008;20(5):536-44. (subscription required)

In this paper, Kathy Freeman, who has previously written a guest essay for Westgard Web, and her colleague Alison Farr apply Sigma metrics and QC design to common veterinary diagnostic tests. QC in veterinary testing is not a subject that is well covered in the scientific literature.

What's most interesting from our point of view is that in order to calculate Sigma metrics and perform QC Design on these tests, Freeman and Farr needed key information: quality requirements for veterinary tests for the major non-human species (cat, dog, horse). For the most part, the requirements don't exist, or at least a set of goals is not in widespread circulation. So Freeman and Farr did a survey review and made some assessments of test interpretation in their own laboratory. The result is the largest list of quality requirements for veterinary testing that we've ever seen. We excerpted the table, with Freeman's permission, here. 

It's a comprehensive paper, covering the method principles, decision levels, quality requirements, Sigma metrics, and QC Design with rule implementation. Highly recommended.