Four horned Icelandic sheep: rarest of the rare
There is not a lot known about the genetics of four
horns, but I will share here some of what has been
written. Dr. Olafur Dyrmundsson of The Farmer's
Association of Iceland wrote in a letter to the editor of
the ISBONA Newsletter (Volume 5, Issue 1, Winter
2001) the following comments:

"...from my point of view we have the duty to
preserve rare genetic characteristics such as
4-hornedness in sheep. Fortunately, quite a few are
still found in Iceland. A few individuals, mainly
colored, are found in some flocks, and I know one
farmer who has been concentrating on the breeding of
4-horned sheep for nearly 50 years. Most of them are
brown-piebald (moorit spotted). There was a
4-horned ram in the AI services several years ago and
it may be tmely to offer such possibilities in the near
future."

In an email correspondence with Dr. Dyrmundsson he
wrote me:
"..there are some genes for 4-hornedness around out
there. It is a primitive trait. We don't know much
about the genetics of this trait, it can come from one
parent, it is also found in females and is thus not
linked to sex and not to color. Polled sheep may also
carry the gene or genes for 4-hornedness..."
The photo above is of a 4-horned ram that resides in
a park/zoo in Reykjavik, Iceland. Photo courtesy of
Shawn Carlson.
Some of the Icelandic sheep breeders in North
America had been led to believe (myself included)
that we had sheep that were four horned.
Occasionally rams are born that have small 3rd
and/or 4th "horns" that grow from the base of
their horns (see photo above). Dr. Dyrmundsson
has recently clarified that these are
not true
multiple horns, but rather miniature "off-shoots."
Dr. Dyrmundsson reports that true 4 horned
sheep or polled sheep carrying the genetics for 4
horns, have heads that are much "higher." He
also reports that the district in Iceland (Oraefi)
from which the original importations were made
into North America did not have any 4 horned
Icelandic sheep.
Photo courtesy of Brynhildur Inga Einarsdottir