The debate about the length of the tail dock in sheep has surfaced once again. The tail has many functions; the tail in the ewe can shield the udder from chilling at full length. All the tail is held by a Scottish Blackface on the hill, because the shepherd knows that the udder needs protection to escape chilling and potential mastitis in the harsh conditions that the ewe will raise her lamb. Quite often, when a sheep is defecating, the faecal pellets can disperse by shaking its tail.
But what if the tail is left on our green pastures for a long time? Under the tail, soft faeces accumulate, providing a perfect fly strike site. In and around the faecal mass, flies lay larvae, hatching into maggots that strike the flesh below the tails, even entering the rectum and vagina. A fly-striking lamb is not a lovely sight and will almost definitely die.
Nevertheless, completely cutting the tail to stop a fly attack still has its issues. Some rectal prolapses may definitely be hereditary in nature, but many are the result of the removal of this tail. The issue lies in the region’s anatomy; the anus and vulva are kept closed by the muscles of the sphincter, the circular muscles around these openings, which relax to allow the passage of faeces and urine. Any muscle must be attached to a skeletal bone to have strength; these muscles have two attachments to the underside of the tail bones. One passes along the tail forward and the other back. The rear muscle attachment is eliminated when a tail is docked short, thereby weakening these muscles.
The weakness may not instantly be evident, but very frequently when moving faeces, a tailless sheep may invert the rectum. Eventually, the rectum doesn’t return fully, leading to a prolapse. The vogue was for tailless sheep in the late 80s, and there was a serious problem in the test station with prolapsing ram lambs. The issue vanished as tails were held longer.
In the last month of pregnancy, there are inquiries on prolapsing ewes every year during lambing. A short dock and the loss of half the muscle attachment are a contributing factor in many instances. The muscles of the pelvis, including the retainer muscle of the vagina and the sphincter muscle of the vulva, relax in preparation for lambing in the last month of pregnancy under the influence of hormonal transition. By these hormonal changes, an already weakened vulva muscle is made weaker; a vaginal prolapse occurs. Of course, because of other variables, such as selenium deficiency at this stage of gestation, prolapses will occur in ewes with longer tails.
If done with caution and correctly, each method of docking, the rubber ring, the knife, the Burdizzo and the knife will yield the same results. At the moment, the suggested position is underneath the tail at the end of the web. Since this may leave a tail too short in the adult ewe, work is underway to determine the correct location.
A compromise between no dock, with the chance of flystrike, and a full dock with the likelihood of rectal and or vaginal prolapse is the Code of Practice guideline for docking to the lower lip of the vulva in ewe lambs and to below the rectum in the ram. The committee, which included farmers, veterinarians, and members of a humane society with input from provincial sheep associations, agreed to this recommendation. The human movement’s fears that docking was an unwanted mutilation were also resolved by this agreement. So the question remains, why continue to dock very short or eliminate the tail completely when the length of the compromise meets the sheep’s health needs?