Dr. S. John Martin, BVM&S, MRCVS,
Scientist, Sheep, Goat and Swine
Again the argument on the length
of the tail dock in sheep has surfaced. The tail has many functions;
the tail at the full length in the ewe, will protect the udder
from chilling. A Scottish Blackface on the hill retains all the
tail, because the shepherd knows that in the extreme conditions
that the ewe will be raising her lamb, the udder needs protection
to prevent chilling and possible mastitis. Very often, when a
sheep is defecating, it will shake the tail to spread the fecal
But what happens if the tail
is left long on our lush pastures. Soft feces collect under the
tail, making an ideal site for fly strike. Flies lay eggs in
and around the fecal mass, hatching into maggots which will attack
the flesh under the tails, even entering the rectum and vagina.
A lamb with fly strike is not a pretty site and will almost certainly
However, completely removing
the tail to prevent fly strike has its problems too. Certainly,
some rectal prolapses may be genetic in origin, but many are
the result of this tail removal. The problem lies in the anatomy
of the region; the anus and the vulva are held closed by sphincter
muscles, circular muscles round these openings, which relax to
allow feces and urine to be passed. To have strength, any muscle
must be attached to a bone of the skeleton; these muscles have
two attachments to the underside of the tail bones. One runs
forward and the other back along the tail. When a tail is docked
short, the rear muscle attachment is removed, thus weakening
The weakness may not be apparent
immediately, but very often a tailless sheep will invert the
rectum when passing feces. Eventually the rectum will not completely
return, leading to a prolapse. In the late 80s, the vogue was
for tailless sheep, and there was a significant problem with
prolapsing ram lambs in the test station. As tails were left
longer the problem disappeared.
Every year at lambing, there
are queries on prolapsing ewes in the last month of pregnancy.
In many cases a contributing factor is a short dock and the loss
of half the muscle attachment. In the last month of pregnancy,
the muscles of the pelvis including the retainer muscle of the
vagina and the sphincter muscle of the vulva are relaxing under
the influence of hormonal change in preparation for lambing.
An already weakened vulva muscle is made weaker by these hormonal
changes; the result is a vaginal prolapse. Of course, prolapses
will occur in ewes with longer tails because of other factors,
such as selenium deficiency at this stage of gestation.
Each method of docking, the rubber
ring, the knife, the Burdizzo and knife will produce the same
results if performed with care and correctly. At the moment the
recommended site is at the end of the web underneath the tail.
As this may leave too short a tail in the adult ewe, work is
underway to determine the correct site.
The Code of Practice recommendation
to dock to the lower lip of the vulva in ewe lambs and to below
the rectum in the ram is a compromise between no dock, with the
risk of flystrike, and a complete dock with the possibility of
rectal and or vaginal prolapse. This recommendation was agreed
to by the committee which included producers, veterinarians,
and members of the humane society with input by provincial sheep
associations. This compromise also addressed the concerns of
the humane movement that docking was an unnecessary mutilation.
So the question remains, why to continue to very short dock or
completely remove the tail when the compromise length satisfies
the health needs of the sheep?
This Infosheet was authored by: Dr. S. John Martin,
BVM&S, MRCVS, OMAFRA Veterinary Scientist, Sheep, Goat and Swine
For more information... regarding tail length contact Dr. S. John Martin, BVM&S, MRCVS at:
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