Q: What is wrong with a female hamster if she is walking with a limp to her rear legs, she has blood coming out of her behind (butt) and she seems to be sad?
A: Unfortunately, your hamster sounds very sick and needs to be seen by a veterinarian who can best answer your question by doing a physical examination.
When a hamster starts walking with a limp, I think of a few things, the first thing being trauma. Is there any chance of a child or even adult trying to pick up the hamster and then dropping her? Hamsters can be a bit “nippy” when woken up unexpectedly from sleep. If someone tried to pick up a sleeping hamster, they both may have been surprised, leading to the hamster being dropped.
Blood found around the tail and behind of a hamster can be coming from a number of places. It could represent blood in the urine, which then may mean an infection in the bladder, stones in the bladder or even infection in the kidneys. Another possibility is that the blood could be coming from the gastrointestinal tract due to a bacterial infection, parasites or even cancer. Finally, since this is a female, blood could be coming from the uterus. This happens during pregnancy, an infection in the uterus or even cancer of the uterus.
These are some of the many, many reasons for the signs you are seeing. Only a visit to your veterinarian to allow him or her to examine your hamster will help clear up some of this mystery immediately and get your hamster back on the way to being healthy again.