Hamster With Loose Lump Behind Its Arm

How can a veterinarian determine the cause and possible outcome for a lump behind a hamster’s arm?

Q: My daughter discovered a lump on her hamster yesterday. Moose is about 3 months old. Sam plays with him daily and is certain the bulge just appeared. It feels loose, kind of like an air pocket. It is located slightly behind the hamster’s left arm. We are applying warm compresses as the vet recommended. A month ago, Moose’s abdomen and inner leg were very pink. He was on oral antibiotics for two weeks, which did no good. Six days ago, the vet gave him a trial injection to see if the problem was mites. Moose is a Dzungerian hamster. In your experience, what is your opinion on his condition?

A: Lumps on hamsters come in many varieties, but the cause of lumps can be narrowed down to just a few conditions. The cause of a lump on a hamster could include conditions such as an infection (an abscess), a tumor, a foreign object under the skin or inflammation.

Some of these hamster conditions may respond to a warm compress and some will not. Some of these conditions can be diagnosed with a good physical examination, some by response to treatment, and some with a biopsy of the lump.

How do you decide what is the best way to make a diagnosis of a hamster’s lump? It depends on the hamster, and it depends on how sick the hamster appears.

If this is nothing more than a fat deposit, then no treatment is necessary. But a veterinarian might not know it is just a fat deposit until he or she puts a needle into the fat and looks at the sample under a microscope.

A veterinarian may guess correctly that a hamster’s lump is caused by an infection, but he or she may still need to culture the infection to know which antibiotics will safely destroy the bacteria causing the infection.

For these reasons, it is worth revisiting your veterinarian and letting him or her know that the warm compresses did not appear to change anything, and the lump is still there. It is better to do this sooner than later. If the lump is a sign of something serious, the sooner you get it treated, the better the outcome can be for your hamster.

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Critters · Hamsters