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January 2023

Animal: Dog (Canis lupus familiaris), German Spitz, 4 years, male

Organ: Brain

History: The dog presented to the veterinarian with a circumferential mass on the left shoulder. Furthermore, the owners reported that the animal has been showing walking problems for 4 days as well as increased aggression. Clinical examination demonstrated reduced consciousness, nystagmus, central blindness of the left eye, and precipitated corrective responses in all limbs. Based on the poor prognosis after a CT and MRI scan, the dog was euthanized.

Autopsy findings: In the right, rostral part of the cerebrum, 5 blurred, gray-beige, cheesy, partly coalescing lesions with a diameter of up to 0.9 cm were visible. Similar changes with variable degrees of expression were found in the mass of the left forelimb, several lymph nodes, myocardium, pancreas, kidneys, adrenal glands, and thyroid gland.

Histopathological findings: Multifocal identification of abundant amounts of inflammatory cells consisting of macrophages (some epithelioid macrophages), lymphocytes, and neutrophil granulocytes (some degenerate), and to a lesser extent plasma cells and giant cells (foreign body type). Inflammatory alterations contained masses of elongated, 3 µm wide, septate, irregularly branched about 70°, occasionally colbately distended hyphae with indicated angiocentric distribution patterns. Some areas are necrotic and contain low to moderate amounts of fibrin.

Diagnosis: Brain: panencephalitis, pyogranulomatous and fibrino-necrotizing, multifocal-vasculocentric, chronic, severe, with multinucleated giant macrophages and fungal hyphae (Etiology: Candida albicans)

Comment: The findings are consistent with the pattern of systemic mycosis. Systemic mycoses are typically associated with granulomatous changes in the inner organs and lymph nodes and possibly with subcutaneous fistulation. Clinically, affected animals show, depending on the organ system affected, e.g., chronic emaciation, central nervous system disorders (ataxia, epileptiform attacks, aggression, paresis and/or paralysis), blindness, or abscesses. According to the literature, most pathogens are obligate pathogens and dimorphic, i.e., characterized by a change in phenotype (e.g., transition from filamentous fungal form to yeast form) usually due to temperature. Systemic mycoses are generally a rarely diagnosed disease in Europe. Thus, this disease complex is mainly observed in non-European areas such as the USA.

Contributors: Christiane Helm (Institute of Veterinary Pathology, Faculty of Veterinary Medicine, Leipzig University, Germany), Dr. Regina Scheller (saxony regional institute for public health and veterinary medicine, Leipzig, Germany), Prof. Dr. Thomas Flegel (Department for Small Animals, Faculty of Veterinary Medicine, Leipzig University, Germany), Prof. Dr. Reiner G. Ulrich (Institute of Veterinary Pathology, Faculty of Veterinary Medicine, Leipzig University, Germany)

Pictures: Christiane Helm (Institute of Veterinary Pathology, Faculty of Veterinary Medicine, Leipzig University, Germany)