Medievalists.net has a nice post on what people in the Middle Ages called their pets:
In England we find dogs that were named Sturdy, Whitefoot, Hardy, Jakke, Bo and Terri. Anne Boleyn, one of the wives of King Henry VIII, had a dog named Purkoy, who got its name from the French ‘pourquoi’ because it was very inquisitive.
Geoffrey Chaucer’s The Nun’s Priest Tale has a line where they name three dogs: Colle, Talbot and Gerland. Meanwhile, in the early fifteenth-century, Edward, Duke of York, wrote The Master of Game, which explains how dogs are to be used in hunting and taken care of. He also included a list of 1100 names that he thought would be appropriate for hunting dogs. They include Troy, Nosewise, Amiable, Nameles, Clenche, Bragge, Ringwood and Holdfast. …
In medieval England domestic cats were known as Gyb – the short form of of Gilbert – and that name was also popular for individual pet cats. … Other names for cats included Mite, who prowled around Beaulieu Abbey in the 13th century, and Belaud, a grey cat belonging to Joachim du Bellay in the 16th century. Isabella d’Este also owned a cat named Martino. Old Irish legal texts refer to several individual cats and names them: Meone (little meow); Cruibne (little paws); Breone (little flame, perhaps an orange cat), and Glas nenta (nettle grey). An Irish poem from the ninth century describes how a monk owned a cat named Pangur Bán, which meant ‘fuller white’. The poem begins:
I and Pangur Bán, my cat
‘Tis a like task we are at;
Hunting mice is his delight
Hunting words I sit all night.
“Pangur Bán” is everybody’s favorite Old Irish poem; you can see the original text with translation en face here, and hear it read (in Modern Irish pronunciation) here. But I object strongly to the alleged translation “fuller white”; as Hermocrates says here, “Pangur isn’t an Irish word. It’s actually the cat’s name and could be of Welsh origin (pannwr).” Welsh pannwr means ‘fuller,’ but 1) there’s no way of knowing if that’s actually the source of the Irish name, and 2) even if it is (etymologically), there’s no way of knowing if the cat’s owner (the poet) knew that fact. The only honest way to translate the phrase is White Pangur. (Thanks, Rick!)