Sky News has learnt that Medivet is being sold by Inflexion Private Equity to CVC in a deal worth more than £1bn.
Medivet, which operates around 300 branches and more than 20 round-the-clock clinics across the UK, has been part-owned by Inflexion Private Equity since 2016.
Investment bankers at HSBC ran the Medivet auction process.
Sources said there had been substantial interest from financial bidders because of the opportunity to continue consolidating what remains a fragmented industry.