The UK’s competition watchdog has ordered vets to cap prescription fees at £21 and proposed a cost comparison website, after finding consumers had faced huge price rises and been “left in the dark” over bills.

The Competition and Markets Authority (CMA) said public satisfaction with the cost of services was “low” after a two-and-a-half-year investigation into the £6.7bn market found “there is not strong competition between veterinary businesses”, with large chains dominant.

The watchdog said vets must now tell pet owners that medicines may be cheaper online, let them know they can get a prescription and that this could save them money.

Written prescription fees will be capped at £21 for the first medicine and £12.50 for any additional drugs. However, the cap is not as severe on industry as the £16 limit the CMA had previously proposed. It estimates that these measures could save pet owners hundreds of pounds.

Martin Coleman, the chair of the independent inquiry group, said: “Too often, people are left in the dark about who owns their practice, treatment options and prices – even when facing bills running into thousands of pounds.

“Our measures mean it will be made clear to pet owners which practices are part of large groups, which are charging higher prices, and for the first time, vet businesses will be held to account by an independent regulator.”

Pet owners spent more than £6.7bn on veterinary and other services in 2024, equating to £390 for every pet-owning household. Some spend much more: for example, surgery for cruciate ligament disease, a common procedure for dogs, can cost up to £5,000, occasionally even more.

Other legally binding measures include price lists and a comparison website to increase competition and drive down costs. It will also require large groups to make clear individual vet practices are part of a chain.

Pet owners using a chain vet practice can expect to see changes before Christmas, including standard price lists.

Practices must provide a written estimate in advance for any treatment expected to cost £500 or more including aftercare costs, excluding emergencies, plus an itemised bill.

Average prices of vet services have risen “sharply and much faster than general inflation”, by 63% between 2016 and 2023, the watchdog found. It said it had not seen evidence of a strong link between price increases and investments in quality.

“We have seen internal documents from some LVGs [large veterinary groups] that link price increases to an expectation that pet owners will not react by purchasing less or switching away. We have also seen internal documentary evidence regarding pricing strategies at LVGs that are based primarily on non-quality factors,” it added.

More than 60% of veterinary practices are owned in whole or in part by six large groups: CVS and Pets at Home, both listed on the London Stock Exchange; Medivet, IVC and VetPartners, which are owned by private equity investors; and Linnaeus, whose parent company is Mars Petcare, a subsidiary of the US confectionery group Mars.

CVS said it was “pleased” that the CMA had considered industry feedback on the fee cap, adding that it already complied with many remedies, and published price lists on its practice websites late last year. “While we continue to believe that some of these remedies are not fully justified, we are comfortable with them and believe they are workable,” the company said.

The CMA labelled the 60-year-old regime “outdated”, saying that because it applies to individual vets but not businesses or practices, “key parts of the system are unregulated where concerns have arisen”.

The British Veterinary Association president, Rob Williams,said: “The majority of the CMA’s measures focus on increasing transparency and information, which will help pet owners make more informed choices and support competition, which is a really positive step.

“Delivering highly skilled veterinary medicine is costly and while we recognise prices have risen sharply in recent years this is due to a number of factors, including the higher costs all businesses are experiencing – and vet practices are not immune.”