Etiology:  Pneumocystis oryctolgi is a fungal organism.

Incidence:  Pneumocystis oryctolgi is most commonly found in weanling European rabbits.

Transmission:  Cysts are horizontally transmitted by inhalation through direct contact with shedding rabbits.

Clinical Signs:  Infection is subclinical and produces mild interstitial pneumonia.

Diagnosis:  Histologic recognition of cyst forms on silver-stained sections of lungs with typical pneumonia is commonly performed (A).  Lung tissue can be subjected to Pneumocystis PCR.  Serology can be used to detect anti-Pneumocystis antibody in serum.