title: Canine intestinal histoplasmosis containing hyphal forms.
abstract: A 12-year-old intact male Miniature Schnauzer dog with chronic diarrhea that was unresponsive to empirical treatment was presented to a referring veterinarian. A laparotomy was performed, and formalin-fixed biopsies of duodenum, jejunum, and colon were sent to Oklahoma Animal Disease Diagnostic Laboratory for evaluation. Histologic examination revealed a severe, diffuse, granulomatous enteritis and colitis with intralesional yeast and hyphal forms. Grocott methenamine silver stains revealed short, aseptate hyphae co-mingled with 2-8 µm, oval to round yeast organisms consistent with Histoplasma capsulatum. The atypical presentation of both yeast and hyphal forms prompted identification of the organism. Direct sequencing of a polymerase chain reaction product from paraffin-embedded intestinal samples confirmed the presence of Ajellomyces capsulatus with a homology over 99% to several sequences in GenBank. Ajellomyces capsulatus is the holomorphic name for H. capsulatum. Therefore, the mycelial form of a dimorphic fungus such as H. capsulatum can coexist with yeast cells within lesions of histoplasmosis. Following diagnosis, the dog was treated with itraconazole for 6 months and has improved.
authors.affiliation: Department of Veterinary Pathobiology, Oklahoma State University, Stillwater, OK 74078, USA.
authors.forename: Loni L
authors.initials: LL
authors.lastname: Schumacher
authors.forename: Brenda C
authors.initials: BC
authors.lastname: Love
authors.forename: Mark
authors.initials: M
authors.lastname: Ferrell
authors.forename: Udaya
authors.initials: U
authors.lastname: DeSilva
authors.forename: Ruchika
authors.initials: R
authors.lastname: Fernando
authors.forename: Jerry W
authors.initials: JW
authors.lastname: Ritchey
mesh_terms: D000818:Animals; D004283:Dog Diseases / Q000382:microbiology*; D004285:Dogs; D006658:Histoplasma / Q000235:genetics / Q000302:isolation & purification* / Q000502:physiology; D006660:Histoplasmosis / Q000382:microbiology / Q000662:veterinary*; D025301:Hyphae / Q000502:physiology*; D007410:Intestinal Diseases / Q000382:microbiology / Q000662:veterinary*; D007422:Intestines / Q000382:microbiology / Q000473:pathology; D008297:Male; D010802:Phylogeny