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Updated: Nov 5, 2025
Saline Lavage for Sampling of the Canine Nasal Immune Microenvironment
Published on: December 27, 2024
Mucocutaneous nasal histoplasmosis in an immunocompetent dog
Romy M Heilmann1,2, Mary B Nabity3, Laura K Bryan3
1Department of Small Animal Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX, 77843, USA. romy.heilmann@kleintierklinik.uni-leipzig.de.
Background:
Histoplasma (H.) capsulatum is a dimorphic fungus, and infection is typically via inhalation of microconidia. After conversion to the yeast phase within the lung, the organism is subsequently disseminated to other tissues by macrophages. Nasal histoplasmosis appears to be a rare condition in dogs.
Case Presentation:
We report the clinical case of a 4.5-year-old male neutered Cocker spaniel/Poodle mix, 7.7 kg, body condition score 6/9, that presented with a 3-month history of sneezing and left-sided mucoid nasal discharge. The history also included a mild swelling (transient) of the right carpus with a lameness (grade II-III/IV), coinciding with the onset of sneezing and nasal discharge. The dog lived primarily indoors in the Texas Gulf Coast area. On physical examination, the dog was febrile, and the left nostril was swollen, ulcerative, deformed, and hypopigmented. Mandibular lymph nodes were firm and mildly enlarged bilaterally. Mild lymphopenia, thrombocytopenia, and hyperglobulinemia were noted. Thoracic radiographs were unremarkable. Computed tomography and rhinoscopy revealed swelling of the rostral portion of the left and right nasal passages. Cytology and histology of biopsies of the affected nasal tissue showed pyogranulomatous inflammation and yeast organisms consistent with H. capsulatum. Weak antigenuria was detected on the MVista H. capsulatum antigen test. Treatment with oral itraconazole led to a resolution of the nasal signs and normalization of the appearance of the nostril over 13 weeks, and neither antigenuria nor antigenemia was detected on several recheck examinations. The dog remained in good general and physical condition and showed no signs of disease recurrence more than 6 years after the last examination.
Conclusion:
We report a rare case of nasal mucocutaneous histoplasmosis in an immunocompetent dog, with an excellent clinical response to oral itraconazole. This case documents that histoplasmosis in dogs can affect primarily the nasal cavity, which responds rapidly to triazole antifungal therapy and has a good prognosis. A similar case has only been reported in human medicine in a young adult.
Insights
Nasal histoplasmosis is rare in dogs but treatable. A Cocker spaniel/Poodle mix recovered fully from nasal symptoms using itraconazole, showing a good prognosis for this fungal infection.
Area of Science:
- Veterinary Mycology
- Canine Infectious Diseases
Background:
- Histoplasma capsulatum is a fungus causing infection via inhalation.
- Dissemination occurs via macrophages, with nasal involvement being rare in dogs.
Observation:
- A 4.5-year-old dog presented with chronic sneezing, nasal discharge, and facial deformities.
- Physical and imaging revealed pyogranulomatous inflammation and Histoplasma capsulatum in the nasal passages.
- The dog had mild lymphopenia, thrombocytopenia, and hyperglobulinemia.
Findings:
- Histopathology confirmed pyogranulomatous inflammation and Histoplasma yeast.
- Oral itraconazole treatment led to complete resolution of nasal signs within 13 weeks.
- Antigenuria and antigenemia normalized, with no recurrence over 6 years.
Implications:
- This case highlights nasal mucocutaneous histoplasmosis as a treatable condition in immunocompetent dogs.
- Early diagnosis and triazole antifungal therapy offer an excellent prognosis.
- Canine nasal histoplasmosis can present primarily in the nasal cavity, similar to rare human cases.
