More common in dogs than in cats. Manifested by “scooting” bottoms along the floor. The commonest cause probably involves the anal glands – especially so in dogs. These scent glands sometimes over-fill and irritate. The veterinarian will release the pressure and the irritation ceases.
Worms are said to cause anal irritation and regular worming, say 3 monthly, will reduce this cause.
Any inflammation involving the anus or rectum may cause anal irritation. Anal growths may irritate. Diarrhoea may irritate the anus and any dried on faeces stuck to the anal fur may also irritate.
In all cases the veterinarian will be able to help.