Medical Corner:
Mites, A Very Unusual Case

P.M. van Noort, Veterinarian, The Netherlands
From the July/Aug 1997 Rat & Mouse Gazette

PATIENT: Sunny, a male rat born November 1, 1996, owned by RMCA member, Lisa Westplate.


First visit: February 2, 1997.

Sunny is a nice rat, very alert, eats and drinks normally; only his ears seem to be a bit irregular. There are many little, papillome-like irregularities on both ears. The rat is not bothered by any pruritus (itching). The rest of the body is perfect.

Second visit: February 25, 1997.

It is getting worse. Now the rat has pruritus (the ears are crusty). The rest of the body is still completely normal.

Third visit: February 28, 1997, University of Utrecht.

The rat is anesthetized and little parts of the ear are examined under the microscope. Surprise - there are a lot of sarcoptes mites. This is a rather unique phenomenon among rats.

Sunny With Ear Mites

Sunny Before Treatment
Photo by Lisa Westplate


Ivomec (ivermectin)
Dosage: 0.2 mg/kg injected once a week for a period of three weeks (Editor's note: ivermectin can also be given orally).


The prognosis is very good. Sunny completely recovered within a few weeks of the injections with very little permanent damage to the ears.

Sunny After Treatment

Sunny After Treatment
Photo by Lisa Westplate

Editor's Note: I was unable to find anything in any books about this condition and have never seen or heard about it from any other rat owners. Therefore, I think it is safe to say this is not something we have to worry about our rats getting, but it's nice to know what it is and how to treat it if it ever does appear in our pet rat population.


In mice, there is a condition known as Frizzy rot which appears only on the ears of some Frizzy mice. Not much has been established as to what the cause is, but it normally eats away at the ear. RMCA President, Jackie Jennings, used ivermectin paste to treat a Frizzy mouse with this condition, and, to her great surprise, the problem cleared up in four weeks of treatment. Of course, the flesh that had already been eaten away was gone for good, but no further damage occurred after treatment.