Sporotrichosis (Pet moss disease, Schenck’s disease) is an infectious, chronic, pyogranulomatous, ulcerative disease of cutaneous and subcutaneous tissues of humans as well as animals (Pal, 2007). The disease in cosmopolitan in distribution and has been reported from many countries of the world including India (Baruah et al., 1978; Rudolph, 1984; Itoh et al., 1986; Werner and Werner, 1994; Pal, 2007). Sporotrichosis is most prevalent in temperate and
tropical areas of the world; and the disease occurs in sporadic and epidemic form (Crevasse and Eller, 1969, Pal, 2007). There appears to be no age, sex or breed predilection in the cat and dog, although outdoor animals are probably at a higher risk of acquiring S. schenckii infection. The disease occurs in three forms: 1. Primary cutaneous 2. Cutaneous lymphatic 3. Systemic. The first report of zoonotic transmission of Sporothrix schenckii from the cats was published by
Read and Sperling in 1982. They described an outbreak of disease in five persons who were exposed to an infected cat. The infection is usually acquired as a result of accidental implantation of spores of S. schenckii into the skin by splinter, thorn, moss, wood, and other plant objects. Rarely, the respiratory tract may also act as a portal of entry to the fungus (Pal, 2007). The present communication delineates sporothricosis in feline and canine.
The disease is caused by S. schenckii, a Gram-positive, aerobic, dimorphic fungus which was first identified by Schenck in 1898 (Pal, 2007). The organism was identified from a naturally recurring case in the dog in 1908. The mycelial form occurs in environment as a saprobe and also on Sabouraud medium at 250C. The yeast phase grows on brain-heart infusion (BHI) agar at 370C and in human and animal tissues (Pal, 2007). The fungus is a ubiquitous saprophyte and
is found in the soil with organic matter, timber, hay, straw, rose, thorn, vegetable debris and sphagnum moss (Pal, 2007).
Dog: In dog, sporotrichosis is ordinarily a multinodular disease and nodules resemble those as seen in other species. Cording of the multiple, ulcerated, crusted, alopecic, cutaneous lesions are noticed over the head and trunk. Lymphocutaneous involvement occasionally occurs. However, disseminated sporotrichosis is rarely documented in dogs (Scott et al., 1974). Cording of the lymphatics may also be observed. In some cases, the lesions are found with the
bones, liver, or lungs instead of the skin (Scott et al., 1974; Pal, 2007). Cat: The multiple, circular, raised lesions are characterized by alopecia, crustation and central ulceration. The nodular skin lesions mainly occur on the dorsal aspects of the head, trunk, and tail. The nodules ulcerate and discharge seropurulent exudates. Extremities are also involved (Pal, 2007). Dissemination of disease results into ocular, central nervous system, lymphatic and osseous disorders (Kier et al., 1979; Dunstan et al., 1986; Pal, 2007).
Sporotrichosis is a chronic fungal disease with slow progression and normally with subtle symptoms. Hence, the laboratory help is required to make a confirmative diagnosis. The organism is isolated by culturing the clinical specimens such as skin, synovial fluid and cerebrospinal fluid (CSF) on Sabouraud medium, blood agar, BHI agar at 250C and 370C for mycelial and yeast form, respectively (Pal, 2007).
In cat, cytological evaluation of exudates by Giemsa/Wright method is a useful diagnostic tool as exudates from the lesions may contain numerous yeast cells of S. schenckii. The smear of the exudate/ aspirate shows the presence of circular, oval yeast cells and cigar shaped bodies. Histopathological examination of the skin biopsy reveals single or multiple budding yeast cells with periodic-Schiff (PAS), Gomori methanamine silver (GMS) and Griedley fungus (GF)
techniques. Animal pathogenicity test is conducted in laboratory mice by intraperitoneal route. Rapid diagnosis of disease can also be made by application of fluorescent antibody technique (FAT) (Pal, 2007).
Dog with cutaneous form of sporothricosis can be treated with oral droplets of saturated potassium iodide. The therapy should be given for 3-6 months. During therapy, the animals should be monitored for iodide toxicity. Cats are particularly sensitive to iodides and develop iodisim. The most commonly reported signs of iodisim include vomiting, depression, anorexia, muscle twitching, hypothermia, cardiovascular collapse and death. When signs iodide toxicity
appear, treatment should be immediately stopped. Amphotericin B and flucytosine are required if a dog suffers from meningeal sporotrichosis. Amphotericin B causes nausea, vomiting and fever. When sporothricosis causes bone infection and cavity nodules with lungs of the dog,
surgery becomes imperative. If dog can not tolerate itraconazole, fluconazole should be tried. Ketoconazole (5 mg/kg orally) and sodium iodide (20 mg/kg orally) has shown encouraging results in the treatment of cutaneous lymphatic sporothricosis in a cat (Burke et al., 1983). The prognosis in disseminated form depends on the degree of organ involved and the presence of concurrent immunosuppression factors such as feline leukemia virus (FELV) infection.
Prevention and control
In animals, there is no practical method to prevent S. schenckii infection acquired from the environment. However, immediate attention of the traumatic injury to the skin of pets, isolation of infected animals particularly the cat, and confinement of the cat indoor during feline epidemic can reduce the danger of infection. As sporotrichosis is a disease of zoonotic potential, veterinarians must take precautions when dealing with sick cat.
The authors are very thankful to Dr. Man Mohan Keshar and Dr. Ram Krishan Narayan for sending some literature on the subject.
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Burke, M. J., Gareur, G. F. and Macy, D. W. 1983. Successful treatment of cutaneolymphatic sporotrichosis in a cat with ketokenazole and sodium iodide. Journal of Animal Hospital Association 173: 29-33.
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Werner, A. H. and Werner, B. E. 1994. Sporotrichosis in man and animal. International Journal Dermatology 33: 692-700.
Mahendra Pal, Sihin Tesfaye and Sisay Weldegebriel
Department of Microbiology, Immunology, Epidemiology and Public Health, Faculty of Veterinary Medicine. Addis Ababa University. P.O. Box No. 34, Debre Zeit, Ethiopia.