Roundworms (or ascarids) look like short lengths of spaghetti. The adult worms live in the cat’s gut, living off the contents – in effect, sharing your cat’s food. They grow to around 100mm in length, and there may be dozens of them in the gut of a heavily infected animal.
Not surprisingly, they can cause vomiting, diarrhoea and weight loss, along with a dull coat and lack of energy.
The two principal roundworms which can infect UK cats are Toxocara cati (the Cat Roundworm) and Toxascaris leonina.