Figure 5: Demodex Mites in 26-month-old female rat (Inca).
Case history and photos
History
Inca a 26-month-old, spayed, 3-legged female rat housed with cage-mates. As a result of previous injury and severe infection of one of Inca’s hind limbs, prior to adoption, it necessitated in an amputation after coming to the present owner. Inca’s history also includes removal of melanoma of the ear, removal of mammary tumor, and the development of a chronic upper respiratory infection for which she was being treated prior to her development of demodectic mange.
Clinical Signs
This rat initially presented with pink skin and hair loss around eyes and then muzzle. A month later the hair loss had become much worse especially on the belly, face and neck. The owner treated for mites with Revolution (selamectin), a topical ectoparasite treatment, even though the rat was showing no signs of pain or itching. With a possibility of contact allergies to bedding, the rat was moved off of aspen to Vetbed, which is hypoallergenic. Following an additional month there was no improvement and hair loss became worse. Inca was then taken to the vet.
Diagnosis
Mange caused by demodex mites possibly as a result of immunosuppression.
Treatment
The vet performed a skin scrape test and confirmed demodex mites. This species of mite is often seen more commonly in dogs. Inca was prescribed 0.02 mL of 10 mg/mL injectable ivermectin, to be injected subcutaneously once a week. The owner was informed the treatment would most likely be long term and that the injections were to continue until the skin’s appearance became normal and the fur started to re-grow.
Follow-up
The injections were continued once a week for 5 weeks with very little improvement. The owner made the decision to give the Ivermectin orally in baby cereal instead of by injection.
Outcome
The condition began to resolve, and fur to grow back, but other age-related conditions ended Inca’s life before complete recovery.
Photos
 Photo of Inca’s face on the left and the center photo of her belly were taken a month following the initial signs of mite infestation. The photo to the right shows the muzzle shows an additional month later following initial treatment with selamectin. There is increasing hair loss and no real improvement. Inca was taken to the vet at this time. |
 Photo on the left and the center photo show Inca 3 months later and one month into treatment with ivermectin. Improvement to skin is noticeable and fur is beginning to return. The photo to the right is taken 4 months later and 2 months into treatment with ivermectin. Significant improvement is seen in her face with the return of skin to normal and the re-growth of fur. |
Case history and photos courtesy of Shelagh Hall
