Veterinary Medicine - May 2008 - (Page 260) Histoplasmosis PEER-REVIEWED Case example: Histoplasmosis in a Himalayan Cat A 2-year-old neutered male Himalayan cat was presented to the Purdue University Veterinary Teaching Hospital (PUVTH) for evaluation of the primary complaints of lethargy and weight loss of three months’ duration and a decreased appetite of two weeks’ duration. Although the cat lived primarily indoors, free access was allowed outdoors. Anemia (Hct 18%; reference range = 30% to 45%) was diagnosed before referral. On presentation to PUVTH, physical examination abnormalities included pale mucous membranes, a thin stature (body condition score 2/5), and a systolic heart murmur (grade II/VI). An initial complete blood count and serum chemistry profile revealed nonregenerative anemia and hyperglobulinemia. Feline leukemia and feline immunodeficiency virus test results (Snap FIV/FeLV Test—IDEXX Laboratories) were negative. No abnormalities were observed on thoracic or abdominal radiographs. Abdominal ultrasonography demonstrated a single enlarged mesenteric lymph node (0.6 cm). Cytologic evaluation of a bone marrow aspirate revealed erythroid hypoplasia and an increased number of macrophages. Macrophages contained phagocytosed 3- to 4-µm ovoid yeast having a prominent, clear capsulelike cell wall (see figure below). The results of histologic evaluation of the bone marrow were consistent with the cytologic findings. Histoplasmosis was diagnosed, and treatment was initiated with itraconazole (5 mg/kg orally b.i.d.). The cat’s clinical condition improved, and the anemia and hyperglobulinemia resolved in three months. Itraconazole was discontinued after six months of treatment. One year after initial presentation, clinical signs of inappetence and pale mucous membranes returned; the owners declined diagnostic testing. A few days after the onset of clinical signs, the cat died at home. and nonspeci c, while dogs often display gastrointestinal signs. De nitive diagnosis is based on cytologic or histologic identi cation of H. capsulatum. The treatment of choice in cats and dogs is the azole antifungal agent itraconazole. The prognosis depends on the extent of disease and can range from guarded to excellent. The best method of prevention is to avoid exposure to contaminated areas. Horizontal or zoonotic transmission has not been documented, but common-source infection has been observed. ACKNOWLEDGMENTS The authors wish to thank Dr. Craig Thompson, DACVP, for obtaining and providing the digital photomicrographs and Dr. Jacob Rohleder, DACVR, for interpreting the radiographic images used in this manuscript. REFERENCES 1. Davies C, Troy GC. Deep mycotic infections in cats. J Am Anim Hosp Assoc 1996;32(5):380-391. 2. Norton SA. Deep fungal skin diseases. In: James WD, ed. Military dermatology. 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St. Louis, Mo: Saunders Elsevier, 2006;1200-1203,1272-1277. 15 µm .A feline bone marrow aspirate demonstrating a single (arrow) macrophage containing several budding yeast. Several yeast are also free in the background (arrowheads) (Diff-Quik; 100X). 260 May 2008 VETERINARY MEDICINE
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