Hamster loses patch of hair

[visionstatement]

Hello everyone! :) Im so worried about my hamster because the skin in the back of his ear has no hair its literally a sqaure of skin with no hair at all. Im really worried about him and I researched causes of hair loss for hamsters and I'm sure there is no overcrowding in my cage as there are two dwarf hamsters in one big storage box (176 quarts) with extensions. I also do not think that it is a tumor or ticks as I felt no bumps or lumps and there are no bugs I could see or feel. Im really worried that it might damage his health. Could it possibly be scratching, stress, burrowing or alopecia? Hes acting normal though.

[souffle]

If he is in with a mate it may well be overgrooming by the cage mate which is a behavioral issue. Do they ever bicker? It may be best to have them vet checked for mites first but if none are found you may need to do a separation before the skin gets infected.