American Fancy Rat & Mouse Association

This article is from the July/Aug. 1996 AFRMA Rat & Mouse Tales news-magazine.

Invasion of the Fur Mites! EEEKK!

By Pat Bromerek

Well, it happened—the invasion. So quietly they came, so unnoticed they crept and crawled and somehow slithered into aquariums and cages with one thing on their minds—latch on and suck! “Suck all the blood you can guys, ’cause this is what we’re here for!” The eerie chant of the topical rat louse or fur mite (they’re all bad whatever they are) reverberated in our rat room.

But I never heard it. Actually I fell on this problem by accident when I noticed Butterfly losing her fur. I wasn’t really concerned because she, being an old rat, hair thinning is not uncommon and I have seen this condition before. She scratched but never scabbed herself; however, a few of my other rats were doing so. I trimmed back nails and the problem cleared up . . . but it always came back.

Then Nestle’s (a white lab rat) began losing her hair. She, also being an older rat, I wasn’t too concerned but something bothered me about her appearance. She actually felt “grainy”—like sand particles—to the touch when petted and there were flaky brownish “particles scattered throughout her fur.

Butterfly too was getting that way and both of these rats had thick silky fur, but not anymore. Now they looked scruffy and the problem was not improving, even with brushings, baths, or diet change (cut back on dog food treats which can cause scabs and hair loss). So I decided to take them to the vet.

Off To The Vet

Fur mites did cross my mind but only these two showed any positive signs. Our other rats looked good, although some had reoccurring scab problems. There were also some rats that showed no signs at all. “If fur mites are the problem, all of my rats should look like Butterfly and Nestle’s since fur mites are extremely contagious, and this doesn’t seem to be the case.” I thought as I was on my way to the vet.

But earlier in the day Mike thought he saw one of the brownish flakes “moving” on Butterfly’s back while she was playing with us on the kitchen table during her daily romp. “No Way!” I snapped as I grabbed her away from a startled Mike. I looked at her and saw non-moving flakes. But it bothered me. I really was concerned.

I only took Butterfly because she was in “prime” condition. Nestles seemed to be improving a little. I placed her on the examining table and held her as he took a scraping from her fur to read under a microscope. He knew right away what she had before he even took a sample. “This will tell us exactly what type it is but there is definitely a parasite problem going on.” he said.

Five minutes or so later Dr. Bergen asked if I wanted to view the slide under the microscope, which I did, not prepared to witness an absolutely disgusting thing. I placed my eyes on the eye pieces and looked in horror at the squirmy parasites writhing away on the slide, their bellies swollen and red—full of blood! My rat’s blood!!! Next to these miserable things were clusters of rice shaped eggs sticking onto hair follicles. It was revolting! I absolutely couldn’t believe what I just saw, and these creatures on my rats?

Wild Mice

How could this be true?! They don’t live in dirty cages. They don’t eat contaminated food, the bedding is the best available. How did they come in and invade my rats? This is what I explained to Dr. Bergen, trying to find an answer to the problem. He asked, “Did you by chance have any wild mice in your house recently?” I said, “Yes, but it’s been a month or so that we’ve seen any.” They (the mice) were in the rat room and we had a hard time catching them to release outside. “But how did Butterfly get them so bad when she lives in an aquarium?”

It was possible the bedding came in contact with the mice because Butterfly and Nestle’s use Sani-chips® and these two were affected the most seriously. The mice could have run in the open bag and ran out so I never would have seen them but they left behind the problem. This was the only thing we could perceive. Anyway, they’re here and it’s time to treat them. To say the least, I felt so crawly and creepy after the slide viewing. I also was appalled by my rats having this, this, unspeakable thing!

Ivomec Solution

Dr. Bergen mixed up a solution of 1cc Ivermec with 100cc propylene glycol. For 3 weeks each rat got several drops of this medication applied and rubbed on the back of the neck, once weekly. I really was skeptical at first of this method of treatment. It just seemed “too easy” but I did it.


No big results after the first week but some definite improvements going into the second, and by the third week Butterfly looked like her old self, as did Nestle’s. As for our other rats, the “chronic “scabbers” were now clean and have been for a while.

I have had rats for 9 years and never have I ever experienced fur mites or any other external parasite prior to this invasion. I do hope this is the first and last time they visit us ’cause they sure are not welcome here! But there always is a lesson to be learned in anything that at the time besets us and in this case, parasites can come in and invade noiselessly your rats you love and care so much for and it doesn’t matter how well you care for them. If they can get a free ride (in my case the field mice) they will come and reek havoc with the rats and you!! *

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Updated February 25, 2014