The firm previously used Bankside Consultants.
Walbrook will advise on communications with the media and investment community – concentrating on private client brokers in London and the regions.
Paul McManus, who founded Walbrook in April this year, will head up the account. Fellow co-founder Ben Knowles will oversee the investor relations element of the brief.
Simon Riddell, CEO of Animalcare, said: ‘We were very impressed with Walbrook's focus on growth companies and with the team's "hands on" approach to PR and IR. Of particular interest to us was their knowledge of the private client broking communities around the country and this will play an important part in broadening the reach of our investor relations programme.'