Diagnosis of M. hyo infection
Diagnosis is based on
- Clinical signs – chronic, non-productive coughing
Lung lesions upon necropsy
- Lungs are meat-like and purple-gray in color.
- Lesions are typically located in the cranio-ventral regions of the lungs, although swine influenza virus and other pathogens can cause similar lesions.
- Histopathology of lung tissue infected with Mycoplasma hyopneumoniae (M. hyo)
- Enzyme-linked Immunosorbent Assay (ELISA) for detection of antibodies has limited use as antibodies may only be present 6 weeks after infection and test results need to be evaluated on a herd basis
- Polymerase Chain Reaction (PCR) testing is done on lung tissue or lung flushes to demonstrate the M. hyo antigen
- Histological examination of lung tissue can reveal alveolar inflammation and peribronchiolar accumulations of lymphocytes
- Sampling of colostrum for antibodies can support diagnosis in the early stages of the disease, but the sample must be collected within 2 hours after farrowing
To accurately diagnose M. hyo infection, a combination of diagnostic tests is advised.