Understandably, many people mistakenly believe ringworm to be a parasitic worm infection. However, it's caused by a fungus. The condition, a form of dermatophytosis, takes its misleading name from its ringlike appearance on humans. Pet rats are certainly susceptible to ringworm. If you suspect that one or more of yours has an infection, schedule a veterinary appointment promptly.
Fungi called deuteromycetes cause ringworm; Trichophyton mentragrophytes is the type that most commonly affects rats. These fungi take their nourishment from the keratin in skin. Ringworm infections spread easily through direct contact with a surface contaminated with the fungus. Ringworm usually would pass from an infected person or animal to your rat. However, your rat could get ringworm from contaminated bedding, toys, litter, other items in her cage, or even the cage itself. If you can't determine the source of your rat's infection, it probably was another rat carrying the fungus but not showing symptoms. Healthy rats with strong immune function don't always show clinical signs.
Ringworm often forms a circular pattern on rats. If it's symptomatic, you'll probably see red skin lesions on your rat. There's a good chance they'll be ringlike. The lesions might or might not be itchy or otherwise irritate your rat. Skin in the affected area often becomes flaky or scaly, and hair loss there is common. Ringworm can appear anywhere on your rat's body, including her nails, but it most often shows up at the base of the tail or on the back and neck.
Though you might strongly suspect a ringworm infection, your vet will need to make the diagnosis. He'll usually have a good idea that it's ringworm just from a close visual inspection, but because many skin infections and diseases cause similar symptoms, it requires testing. Some ringworm fungi appear fluorescent green when illuminated by ultraviolet light from a Wood's lamp. Your vet might be able to make the determination this way. If not, he examines a sample of scraped-off skin under a microscope to identify what's going on with your rat.
Ringworm infections occasionally clear up on their own. It's not wise to wait and see, though, as they can become recurrent. These infections are highly contagious, putting your other pets and yourself at risk. Your vet will prescribe an oral anti-fungal agent and possibly a topical antibiotic; standard medications for a pet rat include ketoconazole and griseofulvin. Treatment typically lasts four to six weeks. For severe or obviously bothersome symptoms, your vet probably also would recommend a medicated shampoo or lotion to soothe itching, flaking or scaling. You should quarantine infected rats until completion of treatment. After quarantining your rats with ringworm, replace all flooring, bedding and any items you can't clean in your primary cage. Disinfect the cage and other items with a diluted bleach solution and let them air dry. Wash your hands thoroughly with soap and warm water after handling your rats, the cage, and other items to prevent contracting the infection.
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