you should be concerned enough to find the cause. it may not be her urine but rather her vagina. disagreeable odors can be caused by many things but in three-year old girls it is often hygiene. they are either potty trained now or close to it and like to go to the toilet alone. they may urinate or defecate just fine on the toilet but their paperwork may need some improvement. soap residuals from bathing foreign bodies (like toilet paper) can also contribute to genital odors. if a child is not drinking enough fluids the urine will smell quite strong so at least increase her fluid intake to the point where her urine is nearly colorless. little vaginas are also subject to yeast infections so a trip to her pediatrician is in order so she can be properly examined and diagnosed.
my 3 year old daughter has very foul fishy odor in her urine and i don't know what to do. should i be concerned?