My cat has liver disease, trouble walking, and fluid retention. Why?

Hello. I am so sorry that your pet is so unwell. Depending on the cause of the liver disease ( lipidosis, inflammation, infection, or cancer ), prognosis is extremely varied. If he is showing neurologic issues, this could be an indication that you have developed a form of hepatic encephalitis as the result to toxin buildup in the blood stream. The liver's job is to remove toxins, such as ammonia, but if the liver function is depressed enough, a buildup will occur. In general, subcutaneous fluids should not cause overhydration, but with organ failure, this too is a possibility & now the problem becomes how to manage dehydration without doing more damage. This sounds like a very difficult & complex case, so hopefully you have a very good team of doctors working on the problem. The questions you have asked are all very good ones, but difficult to respond to without having your cat's complete history. Tomorrow, ask to have a consult, or sitdown with the attending veterinarian. Write down all your questions & thoughts and keep asking until you are satisfied with their answers. Hopefully they will be able to at least give you some guidance as to what the next steps are to help your kitty back to health. Good luck & thanks for contacting Petco Pet Education Center, formerly Petcoach.