Could I attune a magical item to my pet cat? There don't appear to be any base requirements for attunement.
They likely can attune but it's ultimately up to your GM
Quoting directly from the answer to "Can a familiar attune and wear or use a magic item?":
Yes, [cats] are creatures and, as such, can attune to magic items so long as they meet the requirements for attunement (For example, the magic item cannot require the attuner to be of a certain class, and the DM must deem the familiar capable of wearing/attuning to the particular piece of equipment).
The attunement section states:
Attuning to an item requires a creature to spend a short rest focused on only that item while being in physical contact with it (this can't be the same short rest used to learn the item's properties).
There are no restrictions on what type of creature can do this, so long as a cat can spend an hour focusing on an item the cat can attune to the item. Whether a creature is capable of focusing on an item for an hour is not something the rules define, so it would be up to the GM.