Pyothorax (empyema) is a build up of purulent fluid (infection)
in the space between the chest wall and the lung (pleural cavity).
This fluid gradually compresses the lung producing rapid shallow
breathing which can eventually become critical.
A large range of bacteria have been isolated from cases of pyothorax.
It is unclear how these infections become established however
penetrating wounds, extensions from lung infections, migrating
foreign bodies, and blood borne spread from other sites of infection
in the body have all be suggested as possibilities.
Pyothorax mostly involves both sides of the chest however unilateral
infections are possible. Xrays of the chest may indicate the
presence of the fluid and blood tests may show signs of infection,
however diagnosis is usually made by thoracocentesis (needle drainage
of the pleural cavity) which yields typical purulent fluid.
Treatment must be started as soon as possible and should be aggressive.
Chest drainage by insertion of an indwelling chest catheter (tube
stitched in place) is superior to repeated thoracocentesis. The
drain is let in for 4 to 7 days. Antibiotics should be administered
for at least 4 weeks with some case requiring 10 to 12 weeks.
Deaths are not uncommon despite treatment with mortality rates
of 50% within the first 3 days being reported. Surgery to open
the chest and breakdown any adhesions or abscesses may be necessary
to resolve non-responsive cases.
Cats which survive the initial period of treatment have a good
long term prognosis.
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