I am sorry to hear of your cat's misadventure with fishing line.
Did you remove it from her mouth?
Did she swallow any?
How long ago was it that she ate it?
Fishing line can be dangerous because it can become a linear foreign body and cause the intestines to bunch up if part of it gets stuck. This can cause the intestines to be cut through leading to a life threatening situation and development of septic peritonitis (massive systemic infection and inflammation of the abdomen. The very best recommendation I could make for your kitty at this time is to take her in to the vet to be evaluated and have the fishing line removed safely before it becomes a problem (or address the problem that it caused already). If the fishing line is in her stomach and she just ate it, it may be possible to get it out with endoscopy, however it can be very difficult to fine fishing line in the stomach and the best thing to do may be surgery to remove it.
The other danger to fishing line is the hook at the end of it as this can become stuck and perforate the stomach or intestines causing septic peritonitis as well. A metal hook can be seen on radiographs as can a bouncing pattern, so I recommend this as a way to evaluate her and determine the best method of removal. If you are unable to get in to see your family veterinarian today then I recommend taking her to your nearest 24 hour emergency/specialty hospital as a delay could be very dangerous for her.
I hope I have been able to address your concerns today.
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