Written by Andrew Hagerty
The Cu Sith in Celtic folklore is a large black dog roughly the size of a cow or large calf, The hound is often dark green in color with shaggy fur. It’s tail is usually curled. The eyes are often glowing or flaming. Its paw are described as being the width of a man's hand. The Cu Sith was feared as a harbinger of death as often with black dog lore, and would appear to bear away the soul of a person to the afterlife.
As the Black dogs in Celtic Mythology are often coal black, this hound reportedly gets it’s green hue from fairies, which is where it gets it’s name. Cu Sith literally means “fairy dog” Cu meaning dog in Gaelic and Sith meaning fairy.
Legend has it that the while the creature was capable of hunting silently, it would occasionally let out three terrifying barks. These barks were of such volume, they could be heard for long distances, including by ships at sea. If a person was pursued by the Cu Sith, their only chance to escape the creature was to reach home before it barked three times. If this happened, the victim had no chance of getting away. The women victims were often taken by the hound to the
local fairy mound to provide milk for the fairy children.
Like all fairies, Cu Sith fear iron objects and salt.
From Superstitions of the Highlands and Islands of Scotland by John
Gregorson Campbell, published by James MacLehose and Sons, Glasgow in 1900.
“A man, coming across the links near Kennavara Hill in Tiree, came upon a large black dog, resting on the side of a sandbank. On observing it, he turned aside, and took another road home. Next day he recovered courage, and went to examine the spot. He found on the sand-bank the marks of a dog’s paw, as large as the spread of his palm. He followed these huge footmarks till he lost them on the plain. The dog had taken no notice of him, and he felt assured, from its size, it could be no earthly hound.”