Tularemia in a cat and capybara


Tularemia in a cat and capybara

This post combines two cases Tularemia: the cat and capybara have no relation

History: A 2 year-old male DSH cat had a leg wound 1 week prior, then stopped eating and drinking, became laterally recumbent and depressed.  Temperature, pulse and respiration were within normal limits, PCV was 22% with a neutrophilic leukocytosis and left shift.   The capybara was a captive zoo animal living with several capybaras. Several had severe bloody diarrhea and one died.  It was necropsied by the referring veterinarian who described necrotizing enteritis as the primary gross lesion and submitted fixed tissues for histopathology.

Gross findings: 

Cat: The sclera was icteric, and the left hind-limb hada  2 cm ulcer over the left lateral aspect of the tarsus and tibia with swollen subcutis.  The spleen contained many 1mm diameter white foci that were ell-circumscribed. The liver contained many 1mm white foci. The lung was edematous, dark red, and contained many 2-3mm white foci.  The intestines contained tarry black feces but no other lesions. Many lymph nodes were necrotic with white foci.

Spleen from cat: The capsular surface is raised by well-demarcated white foci that extend into the parenchyma diffusely

Histopathology:

Cat: 

Spleen: Multifocal random necrotizing suppurative splenitis, severe

Spleen, low power magnification, HE stain: At low power there are multifocal random areas of necrosis and suppurative inflammation (purple foci). These dead cells are most likely neutrophils that migrated into the spleen, or pre-existing lymphocytes.

Spleen from cat, HE stain: The white foci seen grossly correspond to these areas of necrotic debris consisting of necrotic and lysed neutrophils, lymhpocytes and red blood cells and splenic stromal cells lined by a rim of intact neutrophils and macrophages

Liver: Multifocal necro-suppurative hepatitis, moderate, generalized

Cat liver at high magnification, HE stain: The liver also contained grossly visible white foci corresponding to these areas of necrotic neutrophils mixed with necrotic hepatocyte debris. These foci are also circumscribed by macrophages and intact neutrophils.

Skin: Focal necrotizing panniculitis, and ulcerative dermatitis with vascular thrombosis

Skin, low power from the cat: The leg wound had severe necrotizing and suppurative cellulitis involving the panniculus, muscle and dermis, with vascular thrombosis (lower right corner)

Lymph nodes: Diffuse necro-suppurative lymphadenitis, severe

Lungs: Multifocal necro-suppurative pneumonia

Stomach: Suppurative gastritis, multifocal, mild

Large intestine: Intraluminal hemorrhage, severe

Capybara: 

Intestine: Diffuse transmural necrotizing enteritis, severe

Lungs: Multifocal necrotizing pneumonia, moderate, generalized

Lymph nodes: Diffuse necrotizing lymphadenitis, severe

Immunohistochemistry:

All affected tissues in the capybara and cat were positive with IHC for Francisella tularensis.

Ancillary findings:

Cat: Francisella tularensis cultured positive

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About Brian

Anatomic Pathologist, VetPath Services, Stone Ridge, NY- musculoskeletal, oral/dental, and sinonasal diseases
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