Preventing by Horse Nails and Shoes
An Arran reciter said: “I was one time staying with a friend here, and I noticed that a horse nail was tied round the churn. I mentioned nothing about it till one day when washing the churn I said, ‘I suppose I may take this off,’ but would she let me, though she did not tell me why it had been put on, but I soon found that out for myself.”
Another authority mentions not the nail but the whole shoe. “The produce of the churn may be effectually protected from the Evil Eye by nailing the shoe of a colt or of an ass to the bottom of the churn. Where this is done there are not on earth that can do it harm, and many people always took care not to expose their churn without a shoe of either a colt or an ass nailed to it.”