My cat is licking her belly and inner thighs bald — everyone says it is stress. Is it?

Take her in. Fur that has been licked off is usually about itch or pain, and stress is a distant third — it is the answer you arrive at after ruling the others out, not the one you start with.

Fleas are the commonest cause, including in an indoor cat and including when you have never seen one. A cat grooms the evidence away: the fleas and the flea dirt go down with the fur. Normal-looking skin under the bald area does not rule fleas out at all — it is exactly what you would expect to see.

Pain is the cause that gets missed. A cat with a sore, inflamed bladder, sore hips, or an itchy allergy will strip the fur over the area that bothers her, so a bald belly can be a bladder problem wearing a skin costume. That is why the vet who sees her will look at the skin, check for parasites, and — this surprises people — will probably want a urine sample too.

Concrete things to do before you go. Comb her with a fine flea comb over a sheet of damp white paper and look for black grit that turns rusty red when it wets. Photograph the pattern from above; a symmetrical strip along the belly and inner thighs is a classic. Press gently around the bald area and note whether she flinches over one particular spot. And look for hairballs, or hair in her stools — that tells you the fur is being swallowed rather than falling out, which is the difference between over-grooming and hair loss.

Bring her in sooner if the skin turns red, raw, weeping or smelly, or if she also starts straining in the litter box.