Sam Campbell was baffled when her mare Koko began acting in
a decidedly unmare-like manner, aggressive to people and trying to mount
other females in the herd like a stallion. It turns out that Koko was no
lady in more ways than one.
Scientists at the University of Guelph discovered that the six-year-old
animal is a rare intersex, or sex-reversed, horse.
Outwardly, Koko has all the characteristics of a mare but was born with
internal testes that were juicing her system with testosterone and making
her act like a stallion.
"I'd been training her and she'd be fine and the next day she'd go wild. Her
behaviour was very erratic," said Campbell, who owns four other horses at
her hobby farm near Cobourg, Ont., east of Toronto. "Then she started
showing stallion-like behaviour, urinating on other horses' feces, mounting
the mare horses."
"I'm thinking, what is wrong with this horse?"
Campbell said a local veterinarian she called in performed an ultrasound
examination on Koko and found what looked like internal testes, a fact
confirmed when the horse was taken to the University of Guelph's Ontario