Sporothrix schenckii complex fungi are found all across the world, thriving in soil and organic plant matter. These fungi, known as Sporothrix, are responsible for causing sporotrichosis, which is commonly referred to as “rose gardener’s disease.” When humans or cats come into contact with the spores of these fungi, it can lead to the development of lesions at the site of infection, such as the skin or respiratory tract. In more severe cases, disseminated sporotrichosis can occur, affecting multiple organs. This case report sheds light on sporotrichosis in an immunosuppressed dog.
Signalment and History
A 5-year-old Welsh springer spaniel, weighing 15.6 kilograms, presented to a referral hospital with symptoms of progressive nasal discharge, difficulty breathing, leg lameness, and skin lesions. The dog had previously been treated by a primary veterinarian for a non-healing skin lesion on the distal thoracic limb, which did not improve with conventional treatment. Additional skin lesions appeared on the thoracic paws and trunk, and intermittent lameness developed. Simultaneously, the dog developed serous nasal discharge and stertor. This dog, previously healthy and living in Nebraska, had no recent travel history.
Physical Examination
During the evaluation at the referral hospital, the dog’s vital parameters were within the normal range. The dog exhibited bilateral serous to mucoid ocular and nasal discharge, along with intermittent stertor. Nonpruritic ulcerated skin lesions were found primarily on the trunk and thoracic limbs. The dog displayed shifting leg lameness and painful flexion of the right carpus. Mildly enlarged lymph nodes were observed in various locations. The remainder of the physical examination was unremarkable.
Differential Diagnoses
Considering the cutaneous lesions, arthropathy, and nasal symptoms that worsened despite immunosuppressive therapy, systemic infectious diseases were the top differentials, with fungal infection being the most likely. Neoplastic diseases and immune-mediated conditions were also considered but deemed less probable. Diagnostic tests were conducted to assess the dog’s systemic health and collect samples for further analysis.
Diagnostic Test Results
Initial diagnostic tests, including blood work and imaging, showed mostly unremarkable results. Impression smears of the skin lesions revealed marked inflammation consistent with Sporothrix species, while lymph node aspirates showed reactive lymphoid hyperplasia. Chest radiographs displayed bronchointerstitial patterns and generalized cardiomegaly. Based on these findings, a presumptive diagnosis of disseminated sporotrichosis was made.
Treatment Plan
The dog was prescribed itraconazole, an antifungal drug, and close monitoring was recommended due to the potential for respiratory distress during treatment. The dog’s immunosuppressive drugs were discontinued, and pain management was initiated. The owners were instructed to follow up with their primary care veterinarian to evaluate the dog’s response to therapy.
Outcome
The dog responded well to itraconazole treatment, with resolution of nasal signs within two weeks. After two months of treatment, the skin lesions and lameness completely resolved. Itraconazole was continued for an additional month to ensure complete resolution before being discontinued.
Discussion
Sporotrichosis is a rare diagnosis in dogs that often mimics other conditions, making it challenging to identify. Dogs typically develop cutaneous forms of the disease, but respiratory and disseminated manifestations can occur. Diagnosing sporotrichosis in dogs requires thorough examination and multiple diagnostic tests, such as fungal staining and culture. Immunosuppression can contribute to the development and progression of the disease, but with proper recognition and treatment, the prognosis is usually favorable.
Conclusion
Sporotrichosis is an uncommon disease in dogs that can be difficult to diagnose due to its resemblance to other conditions. It is crucial to consider sporotrichosis in dogs with multifocal ulcerative skin lesions. Additional diagnostics, including staining for fungal organisms and tissue fungal culture, may be necessary to confirm the diagnosis. Immunosuppression can impact the disease’s progression, but with appropriate therapy, the outlook is generally positive.
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