Regular deworming of cats and dogs based on risk of exposure and disease is a fundamental component of preventative health programs for UK pets. It is also important however, to test adult cats and dogs alongside these treatments to demonstrate that they are effective, reinforce treatment compliance among pet owners and for the early detection of anthelmintic resistance. Concerns about environmental contamination with anthelmintic and drug resistance has also led to the exploration of routine testing for parasites as an alternative to treatment. This presentation will consider which worms of cats and dogs are of concern in the UK, the tests available to detect them and the role of testing in their prevention.