The intended use of the principal or income can be enforced by a person designated for that purpose in the trust instrument, by the person having custody of an animal that is a beneficiary of the trust, or by a person appointed by a court upon application to it by any person. Such person is considered to be a permissible distributee, as defined in RCW
11.98.002, of the trust. A person with an interest in the welfare of the animal may petition for an order appointing or removing a person designated or appointed to enforce the trust.