In the rare case that an older cat is struggling from severe constipation caused by hairball buildup in the gi tract, it can lead to complications. Constipation can proceed to become obstipation, this is the build-up of more severe and stubborn fecal impaction in the digestive system, this can lead to your kitty being hospitalized and undergoing elaborate therapy, including the manual removal of the blockage under anesthetization. If left untreated, severe constipation can prove fatal, therefore keeping on top of hairball control is very important. Take a look at our review of cat food for constipation for more options.