Police made the unusual request after an 86-year-old-man died from injuries sustained when he was hit by a cart, which was being pulled by a horse that "looked out of control."
Ion Iliuta, head of the local veterinary authority, said: "We never had such a request before. Maybe to see what kind of blood it is, yes, but to find out if the animal was drunk, never."
The blood test came back positive.
The 56-year-old owner said he was returning home after having bought the horse earlier at a fair.
Police believe the horse was given alcohol to make it appear stronger and healthier.