Sporotrichosis is a rare but a potentially serious fungal infection that can infect cats, dogs, or people. Because of the risk of people contracting this disease from infected cats, the seriousness of this disease should never be underestimated. Because this disease is not very common, veterinarians or owners may often overlook Sporotrichosis as a potential cause of the symptoms.
What is sporotrichosis and how does an animal acquire it?
Sporotrichosis is an infection caused by the fungus Sporothrix schenckii. This fungus is found in soil and organic debris and is widespread in the U.S. Sporotrichosis is more commonly seen in outdoor dogs, particularly hunting dogs, and in outdoor cats (especially males) that are prone to fighting. In dogs, it is believed that the fungus enters through a puncture wound from a stick or thorn. In cats, it is thought to be transmitted from a scratch or bite from a cat that has contaminated claws or teeth. Humans have become infected through coming in contact with the open, draining sores on infected cats.
What are the symptoms of sporotrichosis?
In cats, the lesions often occur on the head, legs, and tail which are the same locations as most cat bites. The cat bites may abscess and turn into lesions that will not heal and that ulcerate and drain. Cats generally have more of the fungal organisms in the draining fluids and are thus more likely to transmit the disease to humans. Some cats may become systemically sick and develop fevers, loss of appetite, and become lethargic.
In humans, sporotrichosis is more common on the fingers, hands, or face - locations where the person may have had an open wound and come into contact with an infected cat. The nodule may open and drain and the surrounding lymph nodes may become swollen as well.
How is sporotrichosis diagnosed?
The diagnosis of sporotrichosis is very straightforward in the cat. A large number of the Sporothrix organisms are usually present in the wound and draining fluid and they can be identified under a microscope.
What is the treatment for sporotrichosis?
Infected cats are treated with oral potassium iodide. Treatment usually lasts 4 to 8 weeks. Ketoconazole, and the more expensive itraconazole, are sometimes used as an alternative therapy. All of these compounds can be toxic to cats and are administered with caution and at lower doses than dogs.
Since Sporothrix is a fungus and not a bacteria, antibiotics are ineffective. Animals with sporotrichosis should not be given steroids.
How is sporotrichosis prevented?
Prevention consists of prompt treatment of all puncture wounds and minimizing cat fights by neutering cats and keeping them indoors.
Sporotrichosis is fortunately very rare in cats, dogs, and people. It is just common enough that we should keep it in mind if our pets develop nodules or non-healing sores, particularly if they spend time in the woods or are involved in cat skirmishes.
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