Diagnosis | Blackleg

The main tissue sample for definitive diagnosis is the affected muscle, primarily skeletal muscle.  Cardiac muscle or liver can also be used.

Detection of the causative agent from a tissue sample is diagnostic. This procedure differs from the diagnosis of botulism where the detection of the toxin(s) produced by the Clostridium botulinum is crucial for the diagnosis. It should be taken into consideration that C. chauvoei is a normal inhabitant of the gastrointestinal system and, therefore, the muscle from a suspected animal should be sent to and examined in the laboratory no more than a few hours after its death.

Besides anamnesis, clinical signs, necropsy findings and isolation of C. chauvoei, the following techniques are used for the definitive diagnosis of blackleg:

Fluorescent antibody test (FAT) (Fig. 1) that detects C. chauvoei in culture smears and tissue impressions obtained directly during necropsy

Immunohistochemistry (IHC) on histologic sections (Fig. 2) and/or smears of a culture

Polymerase chain reaction (PCR) amplifies the gene sequences that codify the 16sRNA, 16S-23SrDNA and 23SrDNA subunits.