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Gerbils & Hamsters/Robo dwarf with lump


I have two robo dwarf hamsters, one for about a year and a half old and I've had the other under six months. The older hamster (Toasty) has recenty had a pink lump form behind one of his ears- was only noticable a few days ago and has already gotten bigger (but is still small- like 1/3 of a tic tac). He is also greasier an scratches often. As far as we can tell his eating habits and behavior have had no significant change. The hamsters share a cage but are separated by a clear acrylic wall. The younger hamster (Moonpie) shows no sign of illness. Do you have any idea what could be happening?

Hi Madison

Thanks for your question. It is difficult to know for sure what this lump is without seeing Toasty.

A few things spring to mind however.

Firstly it could be mites, especially if he is scratching. It is hard to treat mites in small hamsters because the dosage on the various anti parasite drugs are for Syrians who are considerably larger. Does Toasty have a dust bath? If not and providing the lump isn't raw it would be worth putting one in his cage. You need a shallow dish that he can get into and fill this with chinchilla dust. Hamsters love these and roll around in them - this will help clean his coat.

Another thing that this lump can be is if he has scratched himself and it has infected in which case the increase in size could be pus. In which case if you look at the lump you might find that you can see a ' Head ' on it - you can put tea tree cream on it which is safe for animals - this is a natural antiseptic and might help. If it doesn't then you might need to take him to a vet.

The other thing it could be is a tumor. These are common in older hamsters. Sometimes they don't cause too much trouble but they can grow rapidly and either affect the health of the hamster and/or the  quality of life. Occasionally a vet will consider surgery but to operate on such a small hamster would be very risky and there may be no one prepared to do this. It is a good idea to photograph it and keep a record of any changes.

I hope this helps you.


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Sheila Adby


Syrian hamsters are my specialty, however, I have kept Campbells,Winter Whites and gerbils in the past. I can advise on most subjects associated with hamsters, including housing, bedding, feeding, handling, new borns and catching escapees. I have had some experience of various health problems with hamsters and can offer my opinion and advice on basic health issues, however I am not a qualified vet and therefore cannot recommend drugs etc. My website is


I have been keeping hamsters and other small animals for more than 12 years. My favourites are Syrian hamsters and I foster litters and 'difficult' hamsters for a rescue centre. My job is to tame hamsters ready for re-homing, which is extremely rewarding. I also enjoy looking after new litters and raising the pups. I have co-written a book on hamsters with my local vet and have a website:

Hamsters in Sickness and in Health - Sheila Adby and Dan O'Neill ISBN186163218-5 (Capall Bann Publishing)

Educated to A Level standard in the UK.

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