You need to get her to an experienced avian/waterfowl veterinarian as soon as possible. She needs to be examined, x-rayed and treated. She may have an underlying infection requiring an antibiotic, but she most likely will need a pain killer/anti-inflammatory such as Medicam. The veterinarian will know the dosage to give her based upon her weight.

She may be in some pain or discomfort which makes it impossible to move the leg. The most important issue is to ensure that whatever water feature you have her, that she is able to exit and enter without drowning. Furthermore, she needs to be protected from any predators, so if she is outside of a safe enclosed area, she needs to be brought in at night, otherwise, she will not be able to quickly escape a predator.

If she still has a healthy appetite and can do well with just dragging the leg, she should not be euthanized. As, we have had swans that were able to butt scoot into the water and exit as long as the water feature has a zero entry-flush with the ground. She will just need to be placed in a safe pen (at least 12 x 24 or larger) and somewhere that you can continually watch her. We hope that this information is of benefit. Please let us know how she progresses. The Regal Swan