Overview

• Serology is generally used for the identification of antibodies against a part of a specific antigen and forms one part of the acquired immune response.
• Testing can be performed in diseased animals to assess whether an infectious agent is causing a clinical disease or whether targeted self-antigens are present and in non-diseased animals to assess for protective titers following vaccination, or to assess for endemic disease prevalence within a group of animals. 
• Measurement of total antibody levels to assess for evidence of immunodeficiency is also possible (eg testing the concentration of IgA, IgG and IgM given age related factors).
• Testing is generally performed on blood (serum sample) but can also be performed on other fluids, eg CSF and plasma.
• The antigen can be from many different sources, eg bacterial, viral, fungal, parasitic or protozoal as well as self-antigens such as thyroglobulin.
• Detection of antibody is generally IgG but can involve detection of other antibodies, eg IgM or IgE. Presence of IgM antibody implies recent disease and therefore the infectious agent is more likely to be causing clinical signs if acute, although this is not exclusive.

Principles of interpretation

Commonly used test methods

Vaccine associated serological testing

Further Reading

Publications

Refereed papers

• Recent references from PubMed and VetMedResource.
• Day M, Horzinek M C, Schultz R D et al (2016) WSAVA Guidelines for the vaccination of dogs and cats. JSAP 57 (1), E1-45 PubMed.
• Burr P & Snodgrass D (2004) Demystifying diagnostic testing: serology. In Practice 26 (9), 498-502 VetMedResource.
• DiUlio M (1999) Veterinary Immunology and Serology: Clinical Laboratory Diagnostics​ Laboratory Medicine 30 (1), 36-40 Oxford Academic.

Other sources of information

• Ford R B (2013) Antibody titers versus vaccination. Today's Veterinary Practice May/June, 35-38.
• Hendrix C & Sirois M (2007) Laboratory Procedures for Veterinary Technicians. 5^th edn.