Sporotrichosis in Dogs
Sporotrichosis, a fungal ailment, affects various parts of dogs’ bodies, including the skin, respiratory system, bones, and occasionally the brain. The culprit behind the infection is the nearly omnipresent dimorphic fungus known as Sporothrix schenckii. This fungus typically infiltrates through direct contact, either via skin abrasions or inhalation. Originating from the environment, Sporothrix schenckii is commonly found in soil, plants, and sphagnum moss. Moreover, it can be transmitted between different animal species and between animals and humans.
In dogs, this disease is more prevalent among hunting dogs due to the heightened risk of puncture wounds from thorns or splinters.
Symptoms and Types
Cutaneous sporotrichosis:
- Skin surface displays bumps or lesions, along with swollen lymph glands.
- Multiple nodules may appear, often draining or crusting, mainly affecting the head or trunk.
- Previous trauma or puncture wound in the affected area can sometimes be observed.
- Limited response to previous antibacterial therapy.
- Combination of cutaneous and lymph form: Typically an extension of the cutaneous form, spreading via the lymphatic system, leading to the emergence of new nodules and draining tracts or crusts.
- Lymphadenopathy (lymphatic system disorder) is a common occurrence.
Disseminated sporotrichosis:
- Occurs rarely, when the initial infection disseminates to a secondary location within the body.
- Manifests with systemic signs of malaise and fever.
- Osteoarticular sporotrichosis: Infection spreads to the bones and joints.
- Sporotrichosis meningitis: Infection spreads to the nervous system and brain, exhibiting symptoms such as loss of appetite (anorexia) and weight loss (cachexia).
Pulmonary sporotrichosis:
- Results from the inhalation of Sporothrix schenckii spores.
- Infected animals face an increased risk of developing pneumonia.
Causes
- Animals that come into contact with soil abundant in decaying organic matter seem to be predisposed to the disease.
- In dogs, puncture wounds resulting from foreign bodies increase the likelihood of infection. Similarly, cat scratches present a similar risk.
- Exposure to other infected animals raises the risk of contracting the disease.
- Immunosuppressive diseases should be regarded as a risk factor.
Diagnosis
Your veterinarian will conduct a comprehensive physical examination of your dog, considering the history of symptoms and potential incidents that may have led to the current condition. A thorough blood profile, including a chemical blood profile, complete blood count, and urinalysis, will be performed.
It’s essential to recognize that this disease is zoonotic, meaning it can be transmitted to humans and other animals. Therefore, appropriate precautions must be taken to prevent the spread of infection. Even if your skin is intact, you can still be susceptible to acquiring the disease.
Analysis of fluid from the lesions is often required to confirm an infection. In dogs, special fungal stains may assist in the diagnosis, but a negative result does not rule out the disease. Obtaining samples of deeply affected tissue for laboratory cultures often necessitates surgery to obtain an adequate sample. These samples will be sent for analysis, with a specific mention to the laboratory indicating sporotrichosis as a potential diagnosis. Secondary bacterial infections are frequently observed.
Treatment
Due to the risk of infection in humans, your dog might require hospitalization for initial treatment. However, outpatient therapy could also be considered in many cases. There are several antifungal medications available for treating this infection, and your veterinarian will determine the most appropriate option for your dog. Treatment typically spans several weeks beyond the initial phase before the patient is deemed fully recovered.
Living and Management
Your veterinarian will establish a follow-up appointment schedule, typically every 2–4 weeks, to reassess your dog’s condition. During these appointments, clinical signs will be monitored, and liver enzymes will be evaluated. Any side effects related to treatment will be assessed, and adjustments to the treatment plan will be made based on your dog’s response. If your dog does not respond positively to the therapy, your veterinarian will make necessary changes to the medication.
Prevention
While challenging to prevent due to its widespread presence in the environment, it’s beneficial to identify the source of Sporothrix schenckii to implement measures aimed at preventing recurrent infections.