Pulmonary aspergillosis in horses: 29 cases (1974-1997)

Objective-To analyze medical records and identify factors that veterinarian s can use to prevent pulmonary aspergillosis in horses or that would enable them to diagnose it as early as possible. Design-Retrospective study. Animals-29 horses. Procedure-Medical records were reviewed for horses with pulmonary aspergill osis diagnosed on the basis of characteristic postmortem findings. Informat ion on history, clinical signs, disease progression, and postmortem finding s was obtained. Results-25 of 29 (86.2%) horses had primary (n = 20) or secondary (5) disea se compatible with loss of integrity of the gastrointestinal (GI) tract. Th e remaining 4 horses had a non-GI tract disorder; only 1 of these 4 had cli nical signs associated with the respiratory tract (ie, pleuropneumonia). Al though 22 (75.9%) horses had various signs of respiratory tract disorders, an antemortem diagnosis of Aspergillus pneumonia was made in only 1 horse a nd was suspected in only 1 other. Fungal organisms were seen histologically in tissues other than the lung in 12 (41.4%) horses. Clinical Implications-Horses with enteritis, colitis, typhlitis, or other d iseases of the GI tract that result in mucosal compromise, and horses with clinical signs of respiratory tract disease, particularly if the horse's co ndition is unresponsive to treatment with antimicrobial agents, should be c onsidered at high risk of having pulmonary aspergillosis. Immunosuppression from debilitating disease may also predispose horses to aspergillosis. Bec ause invasive pulmonary aspergillosis can be difficult to diagnose, clinici ans should be aware of clinical and epidemiologic settings in which this di sease would develop.