Which species is NOT commonly affected by Dermatophilus congolensis?

The species that is not commonly affected by Dermatophilus congolensis is goats. Dermatophilus congolensis is a bacterium primarily known for causing skin diseases characterized by crusting dermatitis, notably in horses, cattle, and sheep.

In horses, the condition known as rain scald or rain rot is often the result of infection with this bacterium, particularly in conditions of wet and humid weather. Similarly, in cattle, it can lead to bovine dermatitis, which manifests as scabs and hair loss. Sheep are also susceptible to this organism, which can cause similar dermatoses, especially in wet conditions.

Goats, while they can occasionally be affected, are significantly less prone to infections from Dermatophilus congolensis compared to the other species mentioned. Their skin condition is not typically characterized by the lesions produced by this bacterial infection, making them the least commonly affected among the species listed in the question.