Canine Health Menu

Sporotrichosis

Issue Description
Canine sporotrichosis can be transmitted in dogs when the sporothrix schenckii fungus entered any part of the body that has been wounded or punctured. This open wound that can be a result of a dogfight, thorn, or a stick, can lead to the spread of the infection in the dog's body.


Symptoms
Affected animals have multiple nodules of infection in the skin and tissues underlying the skin. These nodules may be ulcerated, crusted, and have a draining discharge. If a limb is affected, the infection may spread upward toward the body and may cause inflammation and infection to occur in the lymphatic vessels and lymph nodes nearest the affected limb. Secondary bacterial infections can occur. Sporotrichosis should always be suspected in cats with fight abscesses or wounds that do not heal with proper treatment.

Diagnosis
Diagnosing this disease is usually much easier in cats than in dogs. At body temperature, Sporothrix schenckii lives as a yeast form that can be seen on cytology when present. These yeast forms exist in high numbers in the infected nodules of affected cats and are usually identified with relative ease. If cytology is unhelpful in diagnosing sporotrichosis, other testing is available. Fungal culture is probably the next most commonly successful diagnostic tool in the diagnosis of feline sporotrichosis; however, results may take several days to a couple of weeks before they are available. Submission of a sample of tissue for histopathology is another method of diagnosis.

Treatment
Treatment of Sporothrix schenckii infections may be accomplished with the use of a supersaturated solution of potassium iodide (SSKI) at about half the dosage used in dogs. This solution should be given orally and then continued for at least one month after the nodules completely subside (usually 4-8 weeks). Recurrence of infection is common when treatment has not been administered for a long enough period of time. Side effects of SSKI include vomiting, lethargy, weakness, twitching, and a drop in body temperature. If side effects are severe, alternative therapy may be offered. Such therapy includes ketoconazole or itraconazole, which are general antifungal drugs. Cats have an increased sensitivity to these drugs, however, and may not tolerate their use. Antibiotics for secondary bacterial infections should always be a part of therapeutic plans for sporotrichosis.

Public Health Concerns
Transmission of sporotrichosis from cats to humans is a risk that should not be overlooked. Human contact with the discharge or wound infected with Sporothrix schenckii in a cat may produce pustules, nodules, or painful inflamed growths in the skin of humans. This risk does not appear to occur with canine sporotrichosis, probably because there are so few fungal organisms found in the nodules and discharge of dogs. Veterinarians and veterinary clinic staff, as well as owners of infected cats, are at higher risk. Consultation with a physician is recommended for human sporotrichosis.

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