Clinical cases are diagnosed based on the presence of clinical signs plus a positive serological test. A seropositive test by itself has limited value since there is a high incidence of seropositivity in many flocks, particularly in older animals. A positive test does indicate that the animal is infected, but does not indicate that signs or lesions are attributable to infection with the virus.With serological tests, one should keep in mind that the slow development of antibodies following infection must be considered in the interpretation of a negative result (source 2).

Samples for confirmation of diagnosis:

Virology – lung, mammary gland, synovial membrane, brain

Serology – heart blood serum (ELISA, AGID)

Histology – formalin fixed lung, bronchial lymph node, mammary gland, synovial membrane, half of the mid-sagitally sectioned brain

·        Physical exam: see clinical signs

·        Clinical Pathology:

·     Enzyme Linked Immunosorbatant Assay (ELISA):
·        Agar Gel Immunodiffusion (AGID):
·        PCR:

For eradication of the disease from a herd, it is recommended to use both AGID and PCR and to repeat the tests two or three times over several months (source 1).