The wet summer has left animals at increased risk from parasites, which leave a large number requiring pet meds each year.
Over 12 million cats and dogs could be infected by parasites, as 65 per cent of owners have not protected their animals from them with specialist treatments, the Daily Mail reports.
The study, by Bayer Animal Health, found that just 33 per cent of owners think parasites pose a serious risk to their pet's health.
Maggie Fisher, a vet from the European Council for Companion Animal Parasitology, is quoted as saying: "Understanding the risks that parasites present is part of being a responsible pet owner, as is clearing up after your dog or cat and protecting against parasites."
She added that the female roundworm can lay 85,000 eggs every day, which are then spread on shoes, pushchairs and bike wheels.
Parasites can cause blood diseases, which could result in health problems in the animal's joints, heart and central nervous system.