Hawaii Veterinary State Licensing Practice Exam

The characteristic feature of lumpy wool caused by Dermatophilus congolensis infection is the presence of pyramid-shaped masses of scab on the skin. This condition typically manifests in sheep and other livestock, leading to the formation of crusty, scab-like lesions that can be quite distinct in appearance. The scabs are often found in areas where the wool is matted, and the scabbing itself can lead to lumpy formations, which is why the term "lumpy wool" is used.

This condition often results from a bacterial infection that thrives in moist environments, and the scabs arise as a result of inflammation and tissue damage caused by the bacteria. While it may result in discomfort or irritation for the animal, the scabbing is notably what defines the aesthetic characteristic of the infection. Therefore, the unique formation of pyramid-shaped scabs directly ties to the pathology of the lumpy wool condition, underscoring why this feature is considered characteristic of the infection.