Although a pet trust is considered an exception to the rule against perpetuities, it is against public policy to allow a trust to go on indefinitely.
This model law, based on Section 408 of the Uniform Trust Code (UTC), validates a trust for the care of a designated domestic or pet animal and the animal's offspring.
A person having an interest in the welfare of the animal may request the court to appoint a person to enforce the trust or to remove a person appointed.
(c) Property of a trust authorized by this section may be applied only to its intended use, except to the extent the court determines that the value of the trust property exceeds the amount required for the intended use.
One reason was violation of the Rule Against Perpetuities (RAP).
The RAP prohibits granting an estate, "unless the interest vests, if at all, no later than 21 years after the death of some person alive when the interest was created." Essentially, the RAP means that for a pet trust to be valid, the trust must completely dispose of the property within twenty-one years of the measuring life.