Hydrothorax
- Accumulation of oedema fluid
- Same causes as oedema elsewhere
- Due to congestive heart failure, neoplasia in the cavity (especially thymus or regional lymph nodes), protein-losing disease
- Grossly:
- Whitening of pleura in long standing disease due to mesothelial hyperplasia and fibrosis
- Present in some specific diseaes:
- Mulbery heart disease of pigs
- African horse sickness
- Black disease in sheep