«October 2009 SCIENTIFIC COORDINATOR Pierre Le Neindre, Senior research scientist, INRA (French National Institute for Agricultural Research) ...»
Fin erosion is a major problem that has been described for several species of bred fish, particularly for salmonids in European and American farms. The term fin erosion covers a variety of tissue problems ranging from a simple crack in the skin to necrosis of the tissue and even, sometimes, haemorrhaging. Affected tissues show signs of inflammation with hyperplasia of the epithelium, thickening and formation of nodules. In addition, as nociceptors have been found in fins it is probable that these conditions cause nociceptive responses. However, there are no existing studies and targeted research will be necessary to confirm this hypothesis. The main cause of fin erosion would be aggressive biting associated with fighting between individuals and the establishment of a dominance hierarchy. However, other, secondary causes are described in the literature such as handling the fish, abrasive substances in the interior of the rearing tanks, sun burn, exposure to stressful situations, or to corticosteroids which can modify the structure of the skin and its capacity to regenerate.
In general though, there is little data available on the prevalence of these afflictions (all species considered) in the different systems of rearing.
4.3. Sources of known or potential pain associated with mutilations Regardless of the species, poultry, pigs or cattle, one of the principal sources of pain on farms comes from the practice of mutilations that are carried out for a variety of reasons (see Table 6). This is particularly the case when the mutilations are done badly.
4.3.1. Mutilations done to reduce the risk of injuries to animals The case of teeth clipping of piglets Teeth clipping/grinding is seen as a means of reducing injuries to the teats or vulva of the sow as well as to other piglets in the litter. It involves clipping or grinding the canine and incisor teeth (needle teeth) of both jaws, making 8 teeth in all. These milk teeth, which are very sharp at birth, are clipped with a pair of pliers or ground down with an electric grinder by the breeder on the day of birth or soon after. The proportion of the tooth removed varies between 1% and 31% depending on the operator and the tooth being treated. At the behavioural level, the piglets are seen to be defensive during grinding and display strong chewing movements just after teeth clipping/grinding.
By contrast, the interval between the intervention and first sucking is unaffected compared with control animals, similarly to what one sees in other behavioural activities such as lying, standing or activity at the udder. Neither is
there any evidence of activation of stress-response systems in the minutes and hours following teeth clipping.
Histological analysis of longitudinal sections of clipped teeth at different ages shows anomalies that may be potential sources of pain. In particular, one sees breakages in the pulp cavity, dentine fracture, bleeding, pulpitis, abscesses, osteodentines (deposits of calcium that are similar to scar tissue) and necrosis. In all, the frequency of abnormalities is higher when the teeth are clipped with cutting pliers than when they are ground. In view of the fact that the dental pulp is innervated and that the structure of teeth in pigs is similar to that in man, it is highly likely that these sorts of anomalies induce severe pain.
In summary, the information from the literature suggests that there is mild and moderate pain during, and for some hours after teeth clipping to which we can probably add the later discomfort associated with inflammatory reactions and abscesses. Given that several studies suggest that the benefits of teeth clipping are limited, it has been suggested that this technique, which according to the law is not to be used routinely anyway, be abandoned.
The case of debeaking poultry Beak trimming and other mutilations of the beak are the practices that have been most studied and are the most controversial. The reason for these practices is to reduce the prevalence and consequences of pecking which can produce wounding and cannibalism. Pecking behaviour is a potential source of pain in animals that are victims and can also lead in certain cases to high levels of mortality in breeding establishments. Such deaths oblige the farmer to carry out debeaking later in life and so provoke further pain in the debeaked animals. In practice, three techniques are used: 1) cutting the end of the beak, or just the upper jaw for ducks, with small secateurs after immobilising the head, 2) cauterisation using a heated blade, a technique called hot blade beak trimming, 3) infrared beak treatment using a machine that focuses a high intensity infra-red (IR) beam at the tip of the beak.
The different terminologies associated with operations on the beak are thus a function of the extent of the amputation, the method used and the age of the animals (early if done before 10 days and late if done after 10 days); debeaking (more than a third of the beak sectioned early by cutting), beak trimming, (less than a third of the beak sectioned early by cutting) or IR treatment of the beak (less than a third of the beak sectioned early by IR).
Expertise scientifique collective "Douleurs animales" 61 Behavioural and electrophysiological indicators as well as neurobiological knowledge lead us to believe that there is severe pain particularly in the hours after debeaking. Debeaking is more traumatic than trimming and IR treatment of the beak particularly if the operation is done at a late stage. In the chicken, discharges are seen in the intramandibular branch of the trigeminal nerve during the first four hours after trimming. In addition, the long term risk associated with debeaking is the formation of benign tumours of the nerves which are tissue masses formed by uncontrolled and extensive regrowth of Schwann cells and nerve fibres. These tumours, called neuromas, have been described in humans and can provoke severe pain for the life of the animal. This risk is also higher when the amount of beak removed is greater and when the operation is carried out when the bird is four weeks or older.
Functionally beak trimming affects the anatomical integrity of the bird and, as a consequence much of its behaviour such as ingestion of food and drink, preening of feathers, gathering material for nest building, attack and defence.
A hypothesis of chronic pain similar to “phantom pains” experienced by humans after amputations (see Chapter 2) has been proposed whereby the birds have a “phantom beak” but this has been put to question by recent studies on the anatomical organisation of nerve centres in the brain.
The case of tail docking of piglets The aim in tail docking piglets is to avoid cannibalism post-weaning or during fattening, a problem encountered especially in piglets reared on slatted floors. Tail docking is a routine practice in a lot of piggeries regardless of the sex of the piglets. In 2007 more than 90% of piggeries in the European Union were involved. The tail is cut on the day of birth or soon after, either with a scalpel, cutting pliers or a cauterising knife. The amount of tail removed varies from a few millimetres (the tip only) to more than three quarters of the length. Physiological and behavioural studies indicate that the cutting itself is very probably a source of pain. The tail is innervated along its whole length in new-born piglets and they react defensively and cry out as the tail is cut. However no activity in the stressresponse system has been seen in the minutes and hours after tail docking. We could presume that there would be chronic pain following the removal of the tail similar to that described in humans after amputation (see Chapter 2). Indeed, several studies refer to the presence of tumour-like neuromas, known to cause hyperalgesic phenomena, or phantom pains like those in human amputees but this question is still unresolved since it has not been confirmed by behavioural studies in the pig.
In summary, we can suspect mild pain in the hours that follow tail docking and chronic pain in the days and weeks that follow. However the frequency and intensity of chronic pain from this source suffered by piglets are not known.
The case of dehorning cattle The main aim in dehorning calves is to minimize the risks of animals causing injury to each other or to humans by horn butting. It also allows easier access to feeders and systems of confinement. Practically all dairy calves that are to be reared are currently dehorned. It is common in France to dehorn beef breed heifers between 16 and 24 months of age. Animals of beef and hardy breeds generally have horns that are bigger than those of dairy breeds because they were mostly bred for pulling yokes. Cultural or aesthetic factors enshrined in breed standards have maintained these characteristics. The methods of dehorning should be adapted to take into account the specific conformation of the horns. Late dehorning is more frequent in France than in many other countries particularly Anglo-Saxon countries which have favoured the rearing of genetically polled cattle such as the Aberdeen Angus or the selection of genetically polled cattle including lines of beef cattle such as the Charolaise or Limousine that originally come from France. Despite the fact that the practice of dehorning is covered by precise recommendations in the European agreement and the code of good farming practice, it seems that very few breeders use local anaesthetic and analgesics (around 20% for anaesthetic and 10% for analgesics, see also Chapter 5). Legislation in France prevents them from obtaining anaesthetics and practicing local anaesthesia.
Dehorning without anaesthetic or analgesia is known to be painful for both young cattle and adults. It induces, in particular, a big change in cortisol levels and behaviour. Among the methods used, the technique of dehorning (disbudding) by heat cauterisation seems to be less painful than the use of chemical pastes or crayons which can lead to lesions of the eyes if these products run into them. In turn, these methods would be less painful than dehorning by metal shears.
62 Expertise scientifique collective "Douleurs animales"
Overall it appears that for dehorning calves:
• Disbudding by cauterisation is the least painful method.
• The ideal analgesic protocol is a combination of sedation with alpha 2 agonists like xylazine, a preoperative administration of non-steroidal anti-inflammatory drugs (NSAIDs) and local anaesthesia of the cornual nerve before the operation (cf Chapter 5).
Regulations for dehorning cattle and goats: recommendations about dehorning of cattle are laid out in a Council of Europe agreement on farm animals but there is, so far, no such regulation in France. The agreement makes clear that dehorning by methods other than surgical excision should be banned with two exceptions: (1) cattle less than 4 weeks old for which disbudding without anaesthetic by cauterisation or chemical means is possible; (2) for cattle more than 4 weeks old dehorning, destruction or ablation at an early stage of the part producing the horn by surgical methods or by cauterisation is allowed if it is done under anaesthetic by a veterinary surgeon or qualified person. Investigations in France and Canada report various effective field practices carried out by breeders, without systematically resorting to an analgesic protocol. The code of good practice proposed by French professionals recommends dehorning of cattle before 6 weeks of age. For the dehorning of adult animals, it is recommended that an analgesic or, preferably, anaesthetic be used.
The case of removing combs and/or wattles from birds Several procedures are used in birds: (1) removing the comb, known as dubbing, is not often carried out in France.
It is often associated with caponisation or with particular genotypes of laying and broiler breeds in which the comb is excessively large. The comb limits the field of vision and is associated with injuries. It reduces feed intake and interferes with copulation ; (2) wattle removal6 is done for the same reasons in reproducing turkeys ; (3) operations on the feet, like declawing and despurring are practices that are designed to prevent wounding during interactions between pen-mates during the growth phase (Muscovy ducks) and during mating during the reproductive phase in certain species.
These practices probably cause pain because some of the tissue removed is richly innervated. However, as far as we know, there are no studies that have analysed the degree to which these practices cause pain.
4.3.2. Mutilations to reduce the risk of outbreak of disease The case of tail docking in cattle In France tail docking in cattle was practised to avoid injuries to the tail and consequent gangrene after trampling underfoot particularly when animals were run on slatted floors. In other countries, especially in New Zealand it was practised to avoid contamination of the clusters of milking machines by pathogens. It is almost never practised in cattle any more in France because it has now been shown that it gives almost no advantage to the animal except in certain therapeutic applications. In addition, the removal of the tails is a source of acute and chronic pain particularly associated with the development of necrotic growths where the cut is made, particularly when done on adult animals.
This practice is authorised in France, including by the code of practice for organic agriculture, even though it is banned in many countries such as Switzerland, Germany, Denmark, Sweden, the United Kingdom and several states of Australia.
The case of tail docking in sheep Tail docking of sheep is practised to (1) reduce soiling of the rear end by faeces and urine and consequently reduce fly-strike and (2) facilitate obstetrical practices and avoid complications at parturition. It is performed most often in Wattle removal is the act of cutting the protruding portion of the caruncle (or wattle), which is a bright red fleshy membrane that covers the 6 head and extends over part of the beak and neck.
Expertise scientifique collective "Douleurs animales" 63 lambs under two weeks of age and is carried out in three major ways: surgically, by cauterisation or by constriction, usually using rubber rings. It is mainly directed towards future breeding animals and especially maiden ewes for reasons of hygiene and the surveillance of lambing. The information in the literature shows that all the methods used are sources of acute and chronic pain even if they do not lead to death. Constriction by rubber rings appears to be the most painful procedure.