- In horses (also calles summer sores)
- Caused by Habronema sp. or Draschia sp. - spread by house flies or stable flies
- In traumatised or moist soft skin
- Grossly:
- Single or multiple tomorous masses that proliferate and ulcerate
- Red to brown, on section have small gritty yellow to white foci
- Microscopically:
- Nodular dermatitis
- Eosinophils, epithelioid macrophages, multinucleated giant cells
- Larvae and necrotic tissue
- Granulation tissue with neutrophils along ulcerated surface