It’s not easy to determine whether a cat is infected with worms, particularly in the early stages. Your cat may suffer from vomiting or diarrhoea, and their coat may lose condition.
A cat with tapeworms may spend more time than usual cleaning its bottom, since the egg-filled worm segments irritate it. You may even find segments in the cat’s bedding - they are pale in colour, and about the size of a grain of rice.
A heavy roundworm infection may cause the cat’s stomach to appear swollen and distended; this is particularly noticeable in kittens.
In general, though, by the time symptoms are noticeable your cat’s health is already being damaged, and the worms have reached maturity. This means that they will be producing eggs and creating a reservoir of infection in the environment.
Far better to worm your cat with Drontal on a regular basis, before the symptoms become obvious.