But Alexander had another side kick: his dog Peritas. He's mentioned offhandedly in Plutarch, so:
Alexander's beloved dog, was named Peritas after the Macedonian name for
the month of January. Alexander raised him from a puppy and when he died named a city after him (Plut., Vit. Alex. 61.3).
Michael Feldman over at Britannica.blog asserts that Peritas was a greyhound and met his doom by the crushing feet of King Darius's war elephants at the battle of Gaugamela.