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.