Dry necrosis of the tail of the young piglet is seen as an occasional sporadic problem in the pig herd but has no particularly significant adverse effects on the pig.
As well as being an aesthetic issue, it is most significant when affecting pigs being sold under conditions requiring an undocked tail, e.g. "green" contracts, for weaners/growers and, in some cases, breeding stock. Furthermore, tail necrosis can occur in older growing pigs at any age as a result of systemic infection or other insult. Occasionally the lesions can trigger further damage from tail biting.
The tail of the new born pig is highly variable in length; the average length of a piglets tail is 9cm but the range is from 5-13cm Necrosis (tissue death) of the tail can occur within the first week of life, although there is no data to link initial length with the onset of necrosis It may appear as a constrictive ring of dead tissue at any point along the tail, cutting off the blood supply to the distal part of the tail, leaving a brown, hard, shrivelled and brittle residue that will snap off easily. Alternatively, the tissue death can appear to start at the tip of the tail - either its natural tip or more commonly the tip left following amputation - and gradually progress up the tail with the same result (Figure 1).
In most cases, the condition is associated with infection into the skin of the tail by bacteria - most commonly Staph hyicus - the usual cause of Greasy Pig Disease. As this organism penetrates into the skin, it causes inflammation that may block the blood supply to the extremities and without a blood supply tissue will die. The underlying cause of tail necrosis is, therefore, damage to the tail and contamination. The primary damage may be the result of:-
1) Abrasion on rough floors as the pigs scrabble to find a teat. In this case, the abrasion may occur at the tail head (Figure 2) or alternatively on the underside of the tail 2-4cm from the base.
2) Fight wounds - the earliest cases of tail biting! The needle sharp teeth of the new born pig can act as an injecting needle, puncturing the skin and introducing bacteria either from the biting piglet's mouth or from the skin surface of the body.
3) Tail docking where clippers are contaminated, or where no effort to cauterise or disinfect the wound is made, bacterial infection gains entry to the cut tissues and progresses up the tail (Figure 1).
Where there is evidence that necrosis has started, the tail should be amputated above the margin of necrosis. By law, this can only be done, without anaesthesia, up to 7 days of age. The cut surface should be cauterised with heat or disinfected using strong iodine.
Prevention of tail necrosis depends upon identifying and rectifying the underlying insult that allows infection to gain entry.
a) Screeding of floors with a smooth finish (avoiding excessive slipperiness) is essential. If not, then liberal use of bedding (shavings, chopped straw, paper) will act as a buffer between the pig and the concrete.
Early clipping of teeth using sharp clippers, individually clipping the 8 needle teeth without shattering. Grinding off the tips of the eyeteeth is a less traumatic alternative. This should be done within 24 hours of birth but only after 6hrs to avoid impeding colostrum intake. Under UK law based on EU Directive, routine reduction of the teeth is not permissible. However, it can be performed under veterinary direction where there is evidence to show that a failure to reduce teeth will cause harm to the sows' udder or other pigs faces, bodies and tails. Management and husbandry should be reviewed prior to resorting to teeth reduction and the necessity to reduce teeth at birth should be continuously reviewed with the veterinary surgeon.
b) Fostering, evening up of litters and provision of milk substitute should reduce the aggression at feeding time and minimise damage between pigs (not just their tails!).
c) Avoid leaving residues of strong disinfectants on floors, which will scald the skin of the newborn pigs (rinse off and dry before re-stocking). Likewise, if lime washing is used, ensure that the lime has fully cured (3-4 days) before stocking. (Uncured lime will also cause severe ulcerative damage the sows' udder).
d) Ensure tail docking equipment is kept clean and is only performed by trained authorised individuals. Clippers should be dedicated to the tails (use different ones for teeth) boiled after use and dipped in surgical spirit between piglets. Surgical spirit should be kept clean and regularly renewed. Dip the cut tail in iodine dressing immediately after docking.
Alternatively, dock tails with a thermocautery tool, either gas or electrically powered and ensure it operates at the correct temperature. If not hot enough, it will not cauterise, if too hot it will cause excessive tissue damage.
As with teeth reduction, routine docking of tails is not permissible but can be performed within 7 days of birth by law (within 72hrs under Red Tractor QA standards) where there is evidence to indicate that a failure to do so is likely to result in damage to the tail by biting. Management and husbandry should be reviewed prior to resorting to docking and the necessity to dock should be continuously reviewed with the veterinary surgeon.
Necrosis of the extremities is a common sequel to systemic infection as a result of arterial damage restricting the blood supply or it can occur as a type III hypersensitivity type reaction where accumulation of antigen/antibody complexes blocks terminal capillaries. The ear tips and tail are most vulnerable but in extremes the lower limbs can be affected. Tail docking at birth plays no part in the later development of dry tail necrosis in growing pigs.
Such lesions usually occur in the wake of a disease outbreak and can be viewed as a recovery phase of the disease. These types of lesions are seen in association with Erysipelas, Haemophilus parasuis and systemic salmonella infections but can also occur as part of the Porcine Dermatitis Nephropathy Syndrome, associated with Porcine Circovirus type 2 (PCVAD) infection.
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