So I spent my first month in New York exploring the city with my poodle at my side. Donald was not a dog fan. When I told him I was bringing Chappy with me to New York, he said, “No.” “It’s me and Chappy or no one!” I insisted, and that was that …

-Raising Trump by Ivana Trump

The only evidence I could find of him ever "having" a pet. But maybe you have found something more substantial to back that he used to have one? For me, the absence of a pet is not a determining factor when it comes to someone's merit or trustworthiness.

So I spent my first month in New York exploring the city with my poodle at my side. Donald was not a dog fan. When I told him I was bringing Chappy with me to New York, he said, “No.” “It’s me and Chappy or no one!” I insisted, and that was that …

-Raising Trump by Ivana Trump

The only evidence I could find of him ever "having" a pet. But maybe you have found something more substantial to back that he used to have one? For me, the absence of a pet is not a determining factor when it comes to someone's merit.