You need urinalysis. Lasix can put cats into kidney failure and excessive drinking and urinating are symptoms of that. Lasix is an important but serious drug, usually used on cats who are in congestive heart failure. If they go into kidney failure you can't use the usual treatment, sub q fluids as that would into the lungs putting them back into CHF. Instead vets will administer fluids intravenously via a "main line" that is implanted into the cats neck.. All of this is to be avoided if possible, my cat went through this.Hi has anyone's cats in this have issues with excessive drinking and urination? He just had blood work but not urinalysis.