Dwarf hamster with maybe one testicle?

Question
Hi Jedediah,

I have a male syrian dwarf hamster that was bought four months ago. Petsmart was not able to tell us how old he was at purchase, but as he has greatly increased in size I would guess he's at most half a year old. I was away for a week and upon returning today, I noticed that he had a large protuding mass on his left hindquarters. (My neighbor who took care of him while I was gone did not notice, but she doesn't play with him as much as I do.) I would just assume that he is maturing and it is a testicle, but the protrusion is only on the left side. Touching the hard mass does not seem to bother him. Am I worrying about this for nothing? Have you noticed this phenomenom before? I've only raised female hamsters before so I don't know what to expect. Thank you so much for your help!

-Joyce

Answer
Dear Joyce,
thank you for your question.
It's normal for male dwarf hamsters to have large testicles, but it's unusual that it's only on the left side. It might be something else, for example an abscess. The testicles should be quite soft and not hard like you have written. I recommend seeing a rodent vet with him to make sure it's nothing unusual.
I hope I was of some help to you
Jennifer