Silly statement. Have you ever been on a farm with a bull who is turned out year round with his beef herd? Some very friendly, docile beef cows are MUCH more dangerous after giving birth then any bull.
Domestic animals are completely different to work around than wild animals who can never be totally domesticated and are always dangerous. Anybody can be hurt working around large domestic animals like a riding horse if they don't know what they are doing. Hardly the fault of the animal.
All large domestic animals are potentially dangerous, with bulls being the best example. One of my classmates in high school was gored nearly to death by a bull that had never shown a sign of agression. Another neighbor was permanently crippled when a sow bit his leg. Also once worked for a man whose wife was killed by a bull. Try telling any of them that its a silly statement.