You can expect a few scuffles whenever a newcomer joins a herd. After all, the dominance hierarchy, or pecking order, has to be reestablished to include this new personality. The regrouping is usually settled in a few hours, most experts agree.
"When you see horses sorting out dominance, it's not usually the top dog versus the lower dog," says equine behaviorist Sue McDonnell, PhD. "More often it's the animals who are closer together in the pecking order."
You can introduce new horses in ways that will reduce accidents despite the inevitable squeals and threatening kicks that ensue. Make the introductions in a roomy pasture with as few traps and barriers as possible. Wait until the footing is firm and safe, not slick and sloppy. If you try to introduce horses from opposite sides of a fence line, there's a high risk of their striking forefeet catching in the fence, so its safer to turn them out together and let them sort things out.
Timing is also important: Washington practitioner Michael Foss, DVM, suggests introducing the new horse during the daytime, so that he can clearly see the lay of the land while he's running, and preferably soon after mealtime, so the horses aren't fighting over or anxious for food.
McDonnell prefers turning the new horse out alone in the pasture so that he can familiarize himself with the area, then adding the other horses one at a time.
"If you simply put the new one out with an established group already in the field, the others may charge or mob him at the gate before he knows his way around," she says.
California practitioner Jerry Black, DVM, suggests that, in cases when two or more new horses are joining an established herd, the newcomers become acclimated to one another before they go out with the whole herd.
This article originally appeared as a sidebar to "Triage for Turnout Injuries" in the June 2001 issue of EQUUS magazine.