Sporotrichosis In Dogs
Sporotrichosis is a fungal disease that affects the skin, respiratory system, bones and sometimes the brain. Infection is caused by mold and yeast fungus, Sporothrix schenckii, which typically infects via direct inoculation - that is, through abrasions of the skin or by inhalation. The origin of the fungus is environmental; it is naturally found in soil, plants and sphagnum moss, but it can be communicated zoonotically between different animal species, and between animals and humans.
Symptoms and Types
Cutaneous sporotrichosis
Bumps, or lesions on the skin surface, swollen lymph glands
Numerous nodules that may drain or crust, typically affecting the head or trunk
Previous trauma or puncture wound in the affected area is a variable finding
Poor response to previous antibacterial therapy
Combination of cutaneous and lymph form—usually an extension of the cutaneous form, which spreads via the lymphs, resulting in the formation of new nodules and draining tracts or crusts.
Lymphadenopathy is common
Disseminated sporotrichosis
Rare, occurs when the initial infection spreads into the body to a secondary location
Systemic signs of malaise and fever
Osteoarticular sporotrichosis occurs when the infection spreads into the bones and joints
Sporotrichosis meningitis occurs when the infection spreads into the nervous system and brain
Symptoms include loss of appetite, and weight loss
Pulmonary sporotrichosis
Occurs as a result of inhalation of Sporothrix schenckii spores
Infected animal is more at risk of developing pneumonia
Causes
Animals exposed to soil rich in decaying organic debris appear to be predisposed
In dogs, puncture wounds associated with foreign bodies provide an increased opportunity for infection. Cat scratches provide a similar opportunity
Exposure to other infected animals increases the risk factor
Immunosuppressive disease should be considered a risk factor
Diagnosis
The vet will perform a thorough physical exam on the dog, taking into account the background history of symptoms and possible incidents that might have led to this condition. A complete blood profile will be conducted, including a chemical blood profile, a complete blood count, and a urinalysis.
It is important to note that this is a zoonotic disease, meaning that it is communicable to humans and other animals, and proper precautions will need to be taken to prevent the spread of infection. Even if you do not have a break in your skin, you are not protected against acquiring the disease.
An examination of the fluid from the lesions is often necessary to confirm an infection. In dogs, special fungal stains may aid in the diagnosis, but a negative finding does not rule out the disease. Laboratory cultures of the deeply affected tissue often require surgery to obtain an adequate sample. These samples will be sent for analysis, along with a special note to the laboratory listing sporotrichosis as a differential diagnosis. Secondary bacterial infections are common.
Treatment
Because of its potential for infection in humans, the dog may be hospitalized for the initial treatment. Several antifungal drugs are available for treatment of this infection. The treatment generally takes some time; at least several weeks after the initial treatment before the patient is considered recovered.
Prevention
Although difficult to prevent because of its prevalence in the environment, it is helpful to determine the source of the Sporothrix schenckii, so that the owner can take steps to prevent repeat infections.
Living and Management
Clinical signs will be monitored and liver enzymes will be assessed. Side effects associated with treatment will be evaluated, and treatment will be adapted according to the dog's reactions.