Objective—To determine clinicopathologic and radiographic
features and etiologic agents in cats that died
as a result of infectious pneumonia.
Procedure—Medical records of cats in which infectious
pneumonia was confirmed by histologic examination
of necropsy specimens were reviewed.
Signalment, clinical signs, and results of a CBC, viral
serologic tests, and thoracic radiography were evaluated.
Infectious agents were classified as bacterial,
viral, fungal, protozoal, or parasitic. Histologic features
(severity, duration, anatomic location, and distribution)
Results—Clinical signs referable to the respiratory
tract were not detected in 14 of 39 (36%) cats, and
results of a CBC (4/18 cats) and radiography (3/13)
were unremarkable. Sixteen of 39 (41%) cats lacked
clinical signs of systemic illness. Etiologic agents
identified included bacteria (n = 21), viruses (11), fungi
(6), protozoa (2), and parasites (1). Cats with clinical
signs related to the respiratory tract (19/24 [79%]
cats) were more likely to have severe histologic
changes than cats without signs related to the respiratory
system (6/14). Twenty-nine of 38 (76%) cats
had histologic evidence of systemic disease, whereas
the remaining cats had lesions limited to the respiratory
Conclusions and Clinical Relevance—Infectious
pneumonia is uncommon in cats. Cats with infectious
pneumonia may lack clinical signs and have
unremarkable results for a CBC and thoracic radiography,
yet frequently have systemic infections.
Therefore, clinicians should maintain an index of suspicion
for pneumonia and evaluate the respiratory
tract when infection is detected in other organ systems.
(J Am Vet Med Assoc 2003;223:1142–1150)