Atlas of pathology
Where: skin and subcutaneous tissue
Differential diagnosis: ViceOther
These pigs show typical signs of injection site reactions and infections, due to a bacterial granuloma in the skin. The usual lesion is a noticeable 2 to 5 cm diameter raised lump in the skin of their neck. The lumps are very firm and painful to the pig when touched. In some pigs, the skin over the centre of the lumps can become ulcerated, with a dark scab formation. Pig farms and pig pens are dirty contaminated environments. When a single syringe and needle is used on many pigs in a pen, there is the strong possibility to collect environmental bacteria on the needle. When that needle is used again on the next pig, then these environmental bacteria can be injected directly into the pig tissue. These mixed bacteria can then set up a local inflammation reaction and create this type of granulomatous lump. This type of needle contamination is more likely when injecting larger pigs housed in groups.