Rat With Mysterious Scabs On Shoulders

What can be done to diagnose a rat with strange scabs on its shoulders?

Q: I have a rat with scabs on his left and right shoulder and a bit of scab extending up his neck. He is 2 years old and has had them for a long time. He opens them up all the time (they seem to be itchy) but no antibiotics will get rid of them and no vets can find what they are. I was told if they were a mast cell tumor he would have been dead a long time ago. Any idea what these scabs could be?

A: Skin problems are some of the toughest issues we have in animals, including pet rats. The biggest reason is that the signs of many skin diseases look exactly the same. A bacterial infection may look like an allergy or a drug reaction or an immune-mediated response.

Veterinarians use two general ways to determine the cause of skin disease. First, we try medications and some simple diagnostics, including skin scrapings looking for parasites. If the rat responds to any medications or we see parasites or their eggs, we can then make a diagnosis. But if the rat does not improve, then we have to go to our other, slightly more invasive, methods of diagnosis.

Other methods of diagnosis include histopathology and deep skin cultures. So, for your rat, it sounds as though you have done the easier methods. At this point, you should consider doing a biopsy of the scabs and the areas around the scabs. The histopathologist will look at the cells under the microscope and should be able to determine if an infection is present, if the cells are normal, and if there is a chance this is any form of cancer.

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