Most skin infections, especially when due to bacteria and yeast, are secondary to another disease process. The most common underlying cause of bacteria and yeast infections in the dog and cat are allergies. Endocrinopathies can also cause skin infections. Clinical signs of skin infections include scaling (flaky skin), hair loss, and itch (scratching, biting, chewing). It is very important to treat the infections as well as the underlying cause so that the infection does not re-occur.
In some cases an infection may be primary - meaning there is no underling cause. A list of primary infections are below:
- Dermatophytosis (ringworm)
- Systemic fungal diseases (cryptococcus)
- Parasitic diseases
Diagnosis of most of these diseases is usually straight forward. The dermatologist may use a combination of skin cytology, skin scrapes, and fungal cultures. For deeper infections, such as mycobacterium, a skin biopsy may be necessary to perform histopathology and culture.