The goddess Epona (“great mare”) — protector of so-called “service” animals such horses, ponies, donkeys and mules — was worshipped by both the Celts and the Romans, and has parallels with the goddess Rhiannon. In Celtic lore, Rhiannon was born at the first Moon Rise and is also known as the Divine Queen of Faeries.
Epona is also associated with fertility and is often pictured with ears of corn, but most often astride or with her horse accompanied by her companion dogs.
I like this simple blessing, which I learned from another healer. Variations of this have been shared and passed along.
Holding your companion animal, or a charm or image of it, in your hands or arms, visualize your pet/companion shining with light, as healthy and safe as possible.
Either out loud, or with your inner voice, say something like this or choose your own blessing/affirmation:
I call on the goddess Epona, and Rhiannon, to watch over my companion, my beloved_________.
Guard and nurture him/her with your blessings and keep him/her safe and healthy.