Lucille Ball with her chihuahua in 1942, a behind-the-scenes shot on the RKO lot during the filming of Seven Days' Leave. Lucy and Desi later raised Schipperkes.
I remember an episode of one of her sitcoms (not the first classic one but a later one in color in the '70s) when Lucy was pretending to speak fluent Spanish and took some friends to a Mexican restaurant.
The waiter who had been given a list of what she actually wanted, but he was called away. The waiter she got instead began writing down everything she was ordering in gibberishy Spanish. The look on the waiter's face!
When the order was brought in, it included all sorts of silly household objects, and sitting in the middle of it all was a chihuahua. I'd love to have still or screen-capture from that.