From what I remember from TV programmes, this is a term used by vets (vetinary surgeons) and others who look after animals, to clarify whether they deal with animals usually kept as pets (eg dogs, cats, hamsters etc), ie "small animals", as opposed to those who look after "large" animals, usually kept on farms or in zoos, eg horses, cattle, Elephants, etc.
Yes, perhaps pets would be more adequate in my context. It's about children and small animals being poisoned by poisonous plants that grow everywhere around us. People should avoid having these plants around their houses.