Why is my cat itching, scratching, or overgrooming?

A dog with itchy skin scratches where you can see it. A cat licks, and licking looks like normal feline behaviour until the coat starts thinning. By the time an owner notices bald strips along the belly, inner thighs or the base of the tail, the itch has usually been going on for some time.

The clue is symmetry and location. Hair loss from overgrooming tends to appear in places the tongue reaches easily and often looks suspiciously tidy, with stubble rather than bare skin. Genuine hair loss from other causes is more often patchy and irregular. If you part the fur and find broken hair shafts rather than empty follicles, that is grooming damage, not hair falling out.

Feline allergic skin disease shows up in a small number of recognisable patterns. Owners often describe them as separate problems when they are one underlying issue.

1. 1

   Symmetrical hair loss

   Thinning along the belly, inner thighs, or flanks, usually even on both sides. Almost always overgrooming rather than hair falling out.

2. 2

   Miliary dermatitis

   Scattered tiny crusts you feel before you see, most often over the back and near the tail base. Classically associated with flea allergy.

3. 3

   Head and neck itch

   Scratching around the face, ears and neck, often hard enough to break skin. Food allergy is over-represented in this pattern.

4. 4

   Eosinophilic lesions

   Raised plaques, lip ulcers, or firm swellings. These look alarming and need a vet, but they are frequently allergy-driven rather than infectious.

As with dogs, parasites come first. Flea allergy remains a leading cause of feline itch, and indoor-only status does not exclude it — fleas arrive on other animals and on people. Rigorous, consistent parasite control for every animal in the household is the cheapest diagnostic step available.

Then environmental allergy, then food. Food allergy accounts for a minority of itchy cats, but it is over-represented in the head-and-neck pattern and in cats with itching alongside digestive signs. The diagnostic route is the same eight-week elimination trial with rechallenge that dogs need.

One practical difference: strict elimination is harder in a multi-cat household, and much harder with a cat that goes outdoors and hunts or gets fed by a neighbour. Both are worth solving before starting the clock rather than discovering mid-trial that the result cannot be interpreted.

Overgrooming does have a behavioural component in some cats, and it is a genuine diagnosis. It is also the explanation owners are given far too early, because it is the one that requires no further testing.

The reasonable position: pursue medical causes first, because they are more common and more treatable, and treat purely behavioural overgrooming as a diagnosis of exclusion. A cat that stops overgrooming on a food trial was not being neurotic.