Atypical Cutaneous Fungal Infections: Sporotrichosis
Sporotrichosis is a fungal infection caused by Sporothrix schenckii, an environmental fungus found in soil, plants, and decaying organic matter. These dimorphic fungi cause sporotrichosis, commonly known as “rose gardener’s disease,” when hosts (most commonly humans or cats) come into contact with their spores. In less complicated infections, lesions are typically limited to the site of infection, such as the skin (following skin trauma) or respiratory tract (following inhalation). In more severe cases, disseminated sporotrichosis may occur. In disseminated sporotrichosis, multiple organs (e.g., skin, joints, lungs) may be affected; immunocompromise may predispose to this outcome. While this disease is well-known in cats, sporotrichosis in dogs is extremely rare. In fact, in 2024, only seven canine cases have been reported across the United States, making it a particularly unusual diagnosis. Recently, we had the opportunity to treat one of these rare cases—a foxhound named Evie—right here at Mid-Atlantic Veterinary Dermatology.
What makes Sporotrichosis So Rare and Why Does It Matter?
Sporotrichosis is uncommon in dogs compared to cats, likely due to differences in behavior and exposure. This rarity makes it a challenging diagnosis for veterinarians; many cases may initially be mistaken for bacterial infections, allergic reactions, or other more common skin conditions. Delayed or missed diagnosis can lead to disease progression, more severe skin lesions, and potential systemic spread.
Recognizing sporotrichosis early is vital because treatment requires long-term antifungal therapy and careful monitoring. Without proper management, the infection can cause significant discomfort and complications.
Key Characteristics of Canine Sporotrichosis
Lesion Appearance: The disease typically presents as nodules or ulcers on the skin. These lesions may drain fluid and fail to heal with conventional treatments.
Common Locations: Lesions are often found on the limbs, face, or areas prone to minor trauma.
Lymphatic Spread: The infection can track along lymphatic vessels, creating a chain of nodular lesions.
Diagnosis: Confirmed by fungal culture or tissue biopsy. Cytology can provide early clues but is not definitive.
Treatment: Requires prolonged antifungal medications, often itraconazole, for several months to ensure eradication.
Evie’s Case: Canine Sporotrichosis Diagnosis
Evie, a foxhound, presented to our clinic with persistent skin nodules that had not responded to multiple courses of antibiotics. After a thorough workup including fungal cultures and biopsy, we confirmed sporotrichosis—the seventh canine case documented in the US in 2024. With consistent antifungal therapy and close follow-up, Evie’s lesions healed completely over time.
We are excited to share before and after photos of Evie’s case to highlight the dramatic improvement possible with correct diagnosis and treatment.
September 2024
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Implications for Veterinarians and Pet Owners
Though rare, sporotrichosis should be considered in dogs with chronic nodular or ulcerative skin lesions that do not respond to typical therapies. Early recognition and diagnosis are critical to avoid prolonged suffering and systemic complications.
If your dog has unusual or persistent skin lesions, especially if they have outdoor exposure in areas with soil or plant material, consult your veterinarian or a veterinary dermatologist. At Mid-Atlantic Veterinary Dermatology, we specialize in diagnosing and managing complex skin diseases like sporotrichosis to help your pet recover fully.
