Updated: Sep 6
"Cats don’t usually lick 'down there' just for entertainment value. When you see cats licking down there, chances are it’s because they’re being hygienic. Since your cat can’t use toilet paper, and since you don’t want to wipe for him, it’s all he can do to stay spotless.
However, if your cat is spending too much time 'down there' it’s actually a medical problem, and it warrants a closer look. If his penis is sticking out, then something’s wrong, as cats rarely show their male parts until they have a feline urethral obstruction (FUO). An FUO is life-threatening because there’s something blocking your cat from urinating. The urethra, a tube from the bladder to the exterior body (eg. penis tip) is a narrow diameter, and grit, crystals, mucous plugs, or blood clots can obstruct it, resulting in an FUO. Untreated, an FUO results in toxic kidney poisons building up in the bloodstream. This causes a temporary acute kidney failure, and can cause severe electrolyte or salt abnormalities. Without prompt medical attention, these electrolyte abnormalities can result in a life-threatening cardiac arrhythmia (eg. abnormal rhythm).
Some other more benign causes for excessive licking 'down there' include irritation to your cat’s penis tip, a bladder or urethral (the tube from the bladder to the tip of the penis) stone, or even having a sterile cystitis. This last one is also called Feline Lower Urinary Tract Disease.
If you notice any of the following signs, see your veterinarian or emergency veterinarian immediately. Your cat is doing all he can to make you realise he needs help.