AU2018307577B2

AU2018307577B2 - Lamb castration clamp and apparatus

Info

Publication number: AU2018307577B2
Application number: AU2018307577A
Authority: AU
Inventors: Vincent MOLONY
Original assignee: Individual
Current assignee: Individual
Priority date: 2017-07-27
Filing date: 2018-07-26
Publication date: 2024-08-15
Anticipated expiration: 2038-07-26
Also published as: WO2019021006A1; GB2579299B; GB2579299A; NZ760845A; GB202001592D0; AU2018307577A1; GB201712080D0

Abstract

A lamb castration clamp (100) comprising: a pair of jaws (102), each jaw comprising an inner contact surface (110) and an outer engagement formation (112) for force to be applied to the jaws; hinge apparatus (106) connecting proximal ends of the jaws such that the jaws are movable from an open position, in which the jaws are spaced apart to receive the neck of the scrotum of a lamb, to a closed position, in which the jaws are close together so that the contact surfaces crushingly clamp the spermatic cords and nerves in the neck of the scrotum so as to stop conduction of the nerves and blood flow to the scrotum; and a retaining element (108) for retaining the jaws in the closed position.

Description

LAMB CASTRATION CLAMP AND APPARATUS

Technical Field The invention relates to a lamb castration clamp and to lamb castration apparatus comprising the lamb castration clamp.

Background Conventionally, male lambs are castrated either in their first week or after 6-8 weeks by application of a tight latex rubber ring, also known as elastrator bands, around the neck of the scrotum. The rubber ring is stretched using elastrator pliers and applied around the neck of the scrotum. Application of the rubber ring cuts off the blood supply to the scrotum and testicles, causing the scrotum to die, decay and be shed. The pain experienced during application of the rubber ring and for 2-3 hours after may be alleviated or reduced by injection of local anaesthetic into the scrotal neck and testicles, although this is not often performed. Another method for castrating sheep involves using a Burdizzo castration device, as described in GB191013319, to crush the spermatic cords one at a time, together with any nerves located in the areas to which the castration clamp is applied. It is essential in using a Burdizzo castration device that an area of the scrotum in between the spermatic cords is not crushed, i.e. is unaffected, so that a blood-supply is maintained to the scrotum. The blood supply to and innervation of the testes is thereby stopped and the testes atrophy and become non-functional. US 2016/0249931 describes a castration clamp to externally compress testicular related tissues, such as ductiles, nerves, and blood vessels leading to the testicles, to castrate an animal. The castration clamp provides a bloodless technique that eliminates the need for open wounds, which are subject to infection. US 5713912 describes A ligating clip having surfaces with slanted ramp members for clamping a tubular vessel. The ligating clip includes a pair of legs, each of which has a proximal end, a distal end and an inner surface. The proximal ends of the legs are joined to define a hinge. The legs may be forced together onto a tubular vessel such that the inner surfaces of the legs are face-to-face in a closed position. A tool for applying the ligating clip is provided with a cutting blade for severing the vessel after the ligating clip has been applied. US 5190560 describes an instrument for castration by ligating and severing blood and seminal vessels. A pistol-shaped tool comprises a hollow body forming a barrel and a hand grip. A yoke pivotally mounted in the cavity of the grip is pivotally connected to a trigger, ligating means and severing means. The vessel to be ligated and severed is positioned in a slotted area at the muzzle of the barrel. The initial pulling of the trigger toward the grip causes blade guards connected to the severing means to surround the vessel or vessels. Further movement of the trigger toward the grip actuates the ligating means to push a ligature from a ligature container and around the vessels. The ligature is forced through ligature compressors

1a

which press the locking ligature onto the vessels. Final movement of the trigger toward the grip moves the severing means to force a blade through the vessels.

Summary It is an object of the invention to provide an improved lamb castration clamp. It is a further object of the invention to provide an improved lamb castration apparatus. An aspect of the invention provides a lamb castration clamp comprising a pair of jaws, hinge apparatus and a retaining element. Each jaw comprises an inner contact surface and an outer engagement formation configured for engagement by clamping pliers for compressive for force to be applied to the jaws by the clamping pliers. The inner contact surfaces have a length of 50-70 mm and a width of 0.2-2 mm and are configured to engage each other along their entire length. The hinge apparatus connects proximal ends of the jaws such that the opposing contact surfaces are in alignment and the jaws are movable by a compressive force from an open position to a closed position. In the open position the jaws are spaced apart to receive the neck of the scrotum of a lamb. In the closed position the jaws are close together so that the opposing aligned contact surfaces crushingly clamp the spermatic cords and nerves in the neck of the scrotum so as to stop blood flow to the scrotum and conduction of nociceptor activity by the nerves. The retaining element is configured to retain the jaws in the closed position. Use of the lamb castration clamp has been observed to reduce the length of time lambs experience acute pain during castration from hours, when castration is performed using the prior art rubber rings, to less than a minute. This is because conduction of nociceptor activity (pain signals), by nerves from the scrotum and testes to the brain, is rapidly blocked during application of the lamb castration clamp. Use of the lamb castration clamp has also been observed to result in more rapid healing, reducing the risk and duration of chronic pain from the castration wound. The lamb castration clamp may therefore enable more humane castration to be performed on lambs, up to the age of 3 months, than is possible using the prior art rubber rings, which is the most commonly used method for castrating lambs of this age. The lamb castration clamp may be applied as easily, quickly and reliably as the rubber rings. As compared with castration using the prior art Burdizzo castration device, the lamb castration clamp of the present invention advantageously requires less skill to reliably obtain effective castration and takes less time to perform, because the Burdizzo device must be applied at least once to the right spermatic cord and at least once to the left spermatic cord. In an embodiment, the contact surfaces are sized and shaped to convert a force applied to the jaws into a pressure of 7-16 MPa applied the neck of the scrotum, so that the contact surfaces crushingly clamp the spermatic cords and the nerves in the neck of the scrotum so as to stop blood-flow to the scrotum and conduction by the nerves. The force is applied to the jaws via the engagement formations. This range of pressures rapidly blocks conduction of pain signals in the nerves. It will be appreciated that the required pressure will depend, at least to some extent, on the age and size of the lamb. In an embodiment, the contact surfaces are sized and shaped to convert up to 100kg applied force into a pressure of 7-16 MPa to be applied to the neck of the scrotum. In an embodiment, the contact surfaces have a length of 50-70 mm. In use, the lamb castration clamp extends across the full width of the scrotum, to ensure that both spermatic cords are crushed at the same time. In an embodiment, the contact surfaces have a width of 0.2-2 mm. This range of widths may enable the lamb castration clamp to convert up to 100kg applied force into 7-16 MPa pressure either by direct manual application of the clamp or application of the clamp using manually operated clamping pliers. This range of widths may also enable stable apposition of the contact surfaces of the jaws of the lamb castration clamp during application of the clamp. In an embodiment, the contact surfaces have a width of 0.2-0.5 mm. This range of widths may enable the lamb castration clamp to convert 10-20kg applied force into 7-16 MPa pressure. Forces in this range can be generated by a user's manual pinch grip and the clamp may thus be applied by a user's manual pinch grip applied to the engagement formations, to apply force to the jaws. In an embodiment, the contact surfaces have a width of 0.5-2 mm. This range of widths may enable the lamb castration clamp to convert 80-100 kg applied force into 7-16 MPa pressure. Forces in this range can be generated using manually operated clamping pliers, which multiply the force applied by a user's manual hand grip. The clamp may thus be applied by a user's manual hand grip, multiplied by the clamping pliers, applied to the engagement formations, to apply force to the jaws. In an embodiment, the hinge apparatus comprises a flexure hinge. In an embodiment, the retaining element comprises a latch flexibly mounted at the distal end of one of the jaws. In an embodiment, the hinge apparatus comprises a hinge barrel mounted in hinge socket and an elastically deformable retaining element configured to generally retain the hinge barrel within the hinge socket, while allowing some movement of the hinge barrel within the hinge socket. This may enable the barrel to move within, and partially out of, the socket to enable sufficient space to be formed between the jaws to accommodate the compressed tissues of the neck of the scrotum. In an embodiment, the retaining element and/or the elastically deformable retaining element comprises at least one elastically deformable ring. This may encourage farmers to adopt use of the lamb castration clamp since they are already familiar with using latex rubber rings for castrating lambs. In an embodiment, the at least one elastically deformable ring is a latex rubber ring. In an embodiment, the first and second contact surfaces have complementary shaped profiles. In an embodiment, the first and second contact surfaces have complementary shaped straight longitudinal profiles. A straight profile may have the advantage of simplicity. In an embodiment, the first and second contact surfaces have generally smooth profiles. A smooth contact surface may have the advantage that in use the skin can slide along the contact surfaces, which may improve distribution of the skin along the jaws. In an embodiment, the first and second contact surfaces have smooth rounded edges. This may avoid breaking and/or cutting of the skin during application. In an embodiment, the lamb castration clamp further comprises a pair of guide arms provided on one jaw such that the inner contact surface of said jaw is located generally between the guide arms. The guide arms are configured to align the inner contact surfaces of the jaws in the closed position and to help gather and retain the tissues of the neck of the scrotum as the jaws are closed. In an embodiment, at least the jaws are formed from a biodegradable material. This may mitigate the need for farmers to collect discarded lamb castration clamps, since the clamps will biodegrade in time. Corresponding embodiments apply equally to the lamb castration apparatus described below. An aspect of the invention provides lamb castration apparatus comprising a lamb castration clamp and clamping pliers. The lamb castration clamp comprises a pair of jaws, hinge apparatus and a retaining element. Each jaw comprises an inner contact surface and an outer engagement formation configured for engagement by clamping pliers for compressive force to be applied to the jaws by the clamping pliers. The inner contact surfaces have a length of 50-70 mm and a width of 0.2-2 mm and are configured to engage each other along their entire length. The hinge apparatus connects proximal ends of the jaws such that the opposing contact surfaces are in alignment and the jaws are movable by a compressive force from an open position to a closed position. In the open position the jaws are spaced apart to receive the neck of the scrotum of a lamb. In the closed position the jaws are close together so that the opposing aligned contact surfaces crushingly clamp the spermatic cords and nerves in the neck of the scrotum so as to stop blood flow to the scrotum and block conduction of nociceptor activity by the nerves. The retaining element is configured to retain the jaws in the closed position. The clamping pliers are double-lever, over-centre clamping pliers having an over-centre toggle. The clamping pliers comprise plier jaws and operating handles. The plier jaws are movable between an open position and a closed position by the operating handles. The plier jaws comprise engagement formations at their distal ends, the engagement formations configured to engage the engagement formations of the lamb castration clamp such that the jaws of the lamb castration clamp are moveable from the open position to the closed position by a compressive force applied the plier jaws moving from the open position to the closed position. Use of the lamb castration apparatus has been observed to reduce the length time lambs experience acute pain, during castration, from hours, when castration is performed using the prior art rubber rings, to less than a minute. This is because conduction of nociceptor activity (pain signals), by nerves from the scrotum and testes to the brain, is rapidly blocked during application of the lamb castration clamp using the clamping pliers. Using the clamping pliers, the lamb castration clamp may be applied as easily, quickly and reliably as a rubber ring. As compared with castration using the prior art Burdizzo castration device, the lamb castration apparatus of the present invention advantageously requires less skill to reliably obtain effective castration and takes less time to perform, because the Burdizzo device must be applied at least once to the right spermatic cord and at least once to the left spermatic cord, whereas the lamb castration clamp can be applied in a single action, using the clamping pliers. In an embodiment, the clamping pliers are configured to apply up to 100kg force to the castration clamp. In an embodiment, the clamping pliers are configured to apply 80-100kg force to the castration clamp. In an embodiment, the clamping jaws comprise engagement formations at their distal ends. The engagement formations are configured to engage the engagement formations of the lamb castration clamp. This may ensure correct engagement of the lamb castration clamp by the clamping plier jaws and correct movement of the jaws of the lamb castration clamp by the clamping pliers.

In an embodiment, the engagement formations of the lamp castration clamp comprise engagement slots and the engagement formations of the clamping pliers comprise engagement lugs configured for engagement with the engagement slots.

Brief Description of the drawings Figures 1 to 4 illustrate a lamb castration clamp according to an embodiment of the invention; Figures 5 and 6 illustrate a lamb castration clamp according to a further embodiment of the invention; Figure 7 is a part sectional view of part of the lamb castration clamp of Figures 5 and 6; Figure 8 illustrates a lamb castration clamp which does not form an embodiment of the invention; Figures 9 and 10 illustrate a lamb castration clamp which does not form an embodiment of the invention; Figures 11 to 13 illustrate a lamb castration apparatus according to an embodiment of the invention; and Figure 14 illustrates the location on a lamb of a lamb castration clamp according to an embodiment of the invention.

Detailed description Embodiments of the invention will now be described with reference to the drawings, by way of example only. The same reference numbers are retained for corresponding features. Referring to Figures 1 to 4, an embodiment of the invention provides a lamb castration clamp 100 comprising a pair of jaws 102, 104, hinge apparatus 106 and a retaining element 108. Each jaw 102, 104 comprises an inner contact surface 110 and an outer engagement formation 112 for force to be applied to the jaws. The contact surfaces 110 have complementary shaped profiles, which in this embodiment are straight, smooth profiles with generally rounded edges, as can be seen in the sectional view in Figure 4. The engagement formations 112 define engagement slots 114 for receiving complementary engagement formations provided at the distal ends of the jaws of clamping pliers. The engagement of the clamping pliers with the engagement formations on the jaws will be described in more detail below with reference to Figures 11 to 13. It will be appreciated that where the lamb castration clamp is configured for manual application, the engagement formations 112 are for engagement by a user's finger and thumb and so do not need to define engagement slots.

The hinge apparatus 106 connects proximal ends of the jaws 102, 104 such that the jaws are movable from an open position, as shown in Figure 1, to a closed, clamping position, as shown in Figures 2 to 4. In this embodiment, the hinge apparatus comprises a hinge barrel on the upper (as orientated in the drawings) jaw 102 and a complementary hinge socket on the lower jaw 104. The hinge socket is open, and the hinge barrel and hinge socket are retained together by an elastically deformable retaining element which in this embodiment is at least one elastically deformable ring 118 located in retaining recesses 122 provided at the proximal ends of the jaws. The retaining element 108 is configured to retain the jaws in the closed position. In this embodiment the retaining element is provided at the distal ends of the jaws and is an elastically deformable retaining element, such as one or more latex rubber rings. The retaining element is located in retaining recesses 122 at the distal ends of the jaws 102,104. Latex rubber rings of the type conventionally used by farmers for castrating lambs may be used as the elastically deformable retaining element, with the advantage of reducing resistance to change by the farmer since they can use existing elastrator pliers to apply the rubber ring over the jaws in a similar action to that which farmers currently use to apply rubber rings directly onto a lamb. A pair of guide arms 120 are provided at both the distal and proximal ends of the lower (as orientated in the drawings) jaw 104. The guide arms act to guide final stages of movement of the jaws 102, 104 into the closed position, so that the contact surfaces 110 are aligned as they are brought into the closed position. The guide arms also help to gather and retain the tissues of the neck of the scrotum between the jaws of the clamp as the jaws are closed. It will however be appreciated that the clamp 100 may be constructed without guide arms. In the open position, the jaws 102, 104 and contact surfaces 110 are spaced apart, to receive the neck of the scrotum of a lamb. In the closed position, the jaws are close together so that the contact surfaces crushingly clamp the spermatic cords and nerves in the neck of the scrotum, as illustrated in Figure 14. This cuts off the blood supply to the scrotum and testes and blocks conduction of nociceptive signals by the nerves, that is to say, pain signals from the scrotum to the central nervous system of the lamb. The smooth, straight profiles of the contact surfaces 110 have the virtue of simplicity, and as the jaws move from the open to the closed position, the skin of the scrotum can slide and be distributed along the contact surfaces. The cross-sectional width of the contact surfaces may be adjusted to vary the pressure that is applied to the skin, underlying tissues and nerves, for example reducing the width to achieve higher pressures. Use of the lamb castration clamp has been observed to reduce the length of time lambs experience acute pain during castration from hours, when castration is performed using the prior art rubber rings, to less than one minute. This is because conduction of nociceptor activity (pain signals) by nerves from the scrotum and testes to the brain is rapidly blocked during application of the lamb castration clamp. Use of the lamb castration clamp has also been observed to result in more rapid healing, reducing the risk and duration of chronic pain from the castration wound. The lamb castration clamp may therefore enable more humane castration to be performed on lambs, up to the age of 3 months, than is possible using the prior art rubber rings, which is the most commonly used device for castrating lambs of this age. The lamb castration clamp may be applied as easily, quickly and reliably as the rubber rings. As compared with castration using the prior art Burdizzo castration device, the lamb castration clamp of the present invention advantageously requires less skill to reliably obtain effective castration and takes less time to perform, because the Burdizzo device must be applied at least once to the right spermatic cord and at least once to the left spermatic cord. Preferably, the Burdizzo device should be applied twice to each spermatic cord. In an embodiment, the contact surfaces are sized and shaped to convert a force applied to the jaws into a pressure of 7-16 MPa applied to the neck of the scrotum. Pressures within this range result in the contact surfaces crushingly clamping the nerves in the neck of the scrotum, so as to stop conduction of nociceptive signals by the nerves, and crushingly clamping the spermatic cords so as to stop blood-flow to the scrotum. In an embodiment, the contact surfaces are sized and shaped to convert up to 100kg applied force into a pressure of 7-16 MPa to be applied to the neck of the scrotum. In an embodiment, the contact surfaces have a length of 50-70 mm so that the lamb castration clamp extends across the full width of the scrotum, to ensure that both spermatic cords are crushed at the same time. In an embodiment, the contact surfaces have a width of between 0.2mm and 2mm. This range of widths may enable the lamb castration clamp to convert an applied force of up to 100kg into 7-16 MPa pressure. The force may be applied to the jaws of the clamp manually or using clamping pliers, as will be described further below. This range of widths may also enable stable apposition of the contact surfaces of the jaws of the lamb castration clamp during application of the clamp. In an embodiment, the contact surfaces have a width of between 0.2mm and 0.5mm. Contact surfaces with these widths may thus effectively have a radial sectional profile. This range of widths may enable the lamb castration clamp to convert 10-20kg applied force into 7 16 MPa pressure. Contact surfaces having such widths may enable the lamb castration clamp to be applied by hand by a user's manual pinch grip. An adult male can typically apply a pinch grip of up to 20 kg and an adult female can typically apply a pinch grip of up to 12-15 kg. In an embodiment, the contact surfaces have a width of 0.5-2 mm and the engagement formations define engagement slots for receiving complementary engagement formations provided at the distal ends of the jaws of clamping pliers. This range of widths may enable the lamb castration clamp to convert 80-100 kg applied force into 7-16 MPa pressure.

The clamp may thus be applied using manually operated clamping pliers, which multiply the force applied by a user's manual hand grip. Application of a force of 80-100kg is achievable by hand, using clamping pliers such as the double lever clamping pliers shown in Figures 12 to 14, These pliers have a force multiplier of between 2 and 3. Mean right hand grip strength is 45-47kg for men aged 20-59 and 28-30kg for women aged 20-59, as reported in N. Massy-Westropp et al, "Hand Grip Strength: age and gender stratified normative data in a population-based study", BMC Research Notes 2011, volume 4, page 127. In an embodiment, the contact surfaces have complementary shaped, longitudinally curved, and smooth profiles. In an embodiment, the castration clamp 100 is moulded from plastic, preferably biodegradable plastic. Referring to Figures 5 to 7, an embodiment of the invention provides a lamb castration clamp 200 comprising a pair of jaws 202, 204, hinge apparatus 106 and a retaining element 108 (not shown in Figures 5 to 7). In this embodiment, the engagement formations 212 are provided on either side of engagement recesses 214 formed in the jaws 202, 204. The engagement formations close the engagement recesses, to form engagement slots for receiving complementary engagement formations on the distal ends of the jaws of clamping pliers. The lower (as orientated in the drawings) jaw 204 is formed from an inner part 208, on which the contact surface 110 is provided and two outer parts 206. Each outer part 206 comprises two guide arms 120, such that a pair of guide arms are provided at the distal and proximal ends of the jaw 204. The inner part 208 is located between the two outer parts 206. The outer parts have a curved upper surface (as orientated in the drawings), so that the contact surface 110 sits above the outer parts; this ensures that the skin of the scrotum maintains good contact with the contact surface on the lower jaw 204. It will be appreciated that the inner part 208 and the outer parts 206 may be formed as separate pieces and connected together, or may be formed as a single, composite piece. Figure 8 illustrates a lamb castration clamp 300 which does not form an embodiment of the invention. The apparatus 300 is similar to the apparatus 200 of Figures 5 to 7, with the following modifications. The contact surfaces 310 of the jaws 202, 204 have complementary shaped toothed, straight profiles. That is to say, the contact surfaces 310 are generally straight, with interlocking teeth formed along the contact surfaces. The presence of the teeth may help to stretch the skin of the scrotum and prevent the skin sliding along the contact surfaces 310 in use. The teeth also increase the length of each contact surface, which may reduce folding of the skin of the scrotum during use. The teeth should be generally blunt and smooth, to avoid breaking or cutting the skin during application.

The contact surfaces 110 may have complementary shaped toothed and longitudinally curved profiles. Both the curved profile and the teeth increase the length of the opposing contact surfaces which may help to stretch the skin, stop sliding of the skin along the contact surfaces and to avoid folds in the skin at the neck of the scrotum. The resulting reduction in pressure caused by the increased length of the contact surfaces may be compensated for by increasing the force applied to the jaws of the castration clamp and/or by making the contact surfaces narrower in width. The contact surfaces should not, however, become so narrow as to effectively form cutting edges when closed by forces in the range described, since the jaws must crushingly clamp the spermatic cords and the nerves, without, at the same time, cutting the skin and other tissues of the neck of the scrotum. Figures 9 and 10 illustrate a lamb castration clamp 500 which does not form an embodiment of the invention. The clamp 500 is formed as a single piece, with the jaws 502, 504 connected by an integrally formed flexure hinge 506. Alternatively, the jaws 502, 506 and flexure hinge 506 may be formed as separate pieces from which the clamp 500 is then assembled. The jaws are movable from an open position, as illustrated in Figure 10, to a closed position, as illustrated in Figure 9. A latch arm 520 is provided on one jaw 502 for engagement with a latch socket 522 provided in the other jaw 504, for retaining the jaws in the closed position. The contact surfaces 510 have complementary shaped, curved, toothed profiles. The jaws 502, 504 are rigid while the flexure hinge 506 is flexible enough to ensure that the jaws are held in the closed position. In use, the flexure hinge will expand as the clamp 500 is closed on the neck of the scrotum, to accommodate the tissues of the scrotum. A reaction force will arise in the flexure hinge as a result, pressing the jaws toward the closed position. Although the clamp 500 is shown in Figure 9 in a fully closed position, it will be understood that, in use on a lamb, the contact surfaces 510 will be close together, clamping a thin layer of skin, wool and other tissues between them. The clamp 500 may be moulded from plastic, including biodegradable plastic. The latch arm 520 may be flexibly mounted at the distal end of the jaw 502. Referring to Figures 11 to 13, an embodiment of the invention provides lamb castration apparatus 600 comprising clamping pliers 610 and a lamb castration clamp 100, as shown in Figures 1 to 4. It will be appreciated that a lamb castration clamp 200 as shown in Figures 6 to 7 may also be used with the clamping pliers. The contact surfaces have a length in the range 50mm and 70mm and have a width in the range 0.5mm and 2mm. The clamping pliers 610 comprise plier jaws 616 and operating handles 612, 614. The plier jaws 616 are movable between an open position (as shown in Figure 11) and a closed position (as shown in Figure 13) by a user applying force onto the operating handles to bring the operating handles together. The castration clamp is engageable by the plier jaws, by engaging the engagement formations provided at the distal ends of the plier jaws 616 with the engagement formations 112 of the lamb castration clamp. The jaws 102, 104 of the lamb castration clamp 100 are moveable from the open position to the closed position by the plier jaws moving from the open position to the closed position. The engagement formations on the plier jaws are configured to engage the engagement formations on the clamp 100. In this embodiment, the engagement formations on the plier jaws comprise engagement lugs 618 provided at the distal ends of the plier jaws, for location in elongate slots 114 defined by the engagement formations 112 on the lamb castration clamp 100. It will be appreciated that the engagement formations on the plier jaws may take a different shape and/or configuration that is engageable with the engagement formations on the clamp 100. In this embodiment, the clamping pliers are double-lever, over-centre pliers having an over-centre toggle to ensure that a repeatable force can applied. The operation of an over centre toggle will be well known to the skilled person and it will be understood that the clamping pliers can be adjusted to set the amount of force required to engage the over-centre toggle. As illustrated in the Figures, the clamping pliers are operable to move the plier jaws from an open position (Figure 11), to a partially closed position in which the lugs engage with the engagement slots 114 on the lamb castration clamp 100 (Figure 12), to the closed position (Figure 13). Providing clamping pliers for applying the lamb castration clamp has the advantage that sufficient force, to overcome the modulus of the tissues at the neck of the scrotum, can be easily and repeatably applied through the castration clamp 100. The application of a lamb castration clamp using the clamping pliers also advantageously enables rapid (around 1s) closure of the clamp onto the neck of the scrotum. The lamb castration apparatus therefore enables faster, more controllable, and repeatable application of lamb castration clamps than can be achieved when applying the clamps by hand. In an embodiment, the clamping pliers are configured to apply 80-100kg force to the castration clamp. The clamping pliers act to multiply the manual hand grip force applied to the operating handles and allow the user to apply this force onto the jaws of the castration clamp, to rapidly close the castration clamp, preferably in around 1s. Referring to Figure 14, in use, the engagement lugs 618 of clamping pliers 610 are engaged in the engagement slots 114 of a lamb castration clamp 100, with both the clamping pliers and the lamb castration clamp in the open position. A right-handed person, for example, might expect to hold the open lamb castration clamp in the clamping pliers 100 in the right hand. They would then catch a lamb, while still holding the lamb castration clamp in the pliers, hold the lamb between the knees and lower legs (head up, belly out and tail to the ground), find and manipulate the scrotum and testicles with the fingers of the left hand while locating the lamb castration clamp, using the pliers, around the neck of the scrotum. The clamping pliers would then be closed to move the jaws 102, 104 of the lamb castration clamp into the closed position, applying approximately 100kg force onto the lamb castration clamp. In the closed position, the jaws 102, 104 are close together so that the contact surfaces 110 crushingly clamp the spermatic cords and nerves in the neck of the scrotum so as to stop blood flow in the spermatic cords and stop conduction of nociceptive signals by the nerves. A lamb castration clamp having jaws with contact surfaces having a length of about 65mm and width of 2mm has been used with 100kg force applied by the clamping pliers, which caused pressure of between 7 and 8 MPa to be applied to the neck of the scrotum. The clamping pliers 610 were held closed for around 10s to ensure that the underlying nerves were crushed and nerve conduction had stopped. Lambs have been observed to experience some intense but short-lived (less than 1 minute) pain during castration using the castration apparatus 600 but this is much less than the 2-3 hours of intense pain suffered after castration using the prior art rubber rings/elastrator bands. As the jaws close on the skin and tissues, the Young's modulus of the skin and tissues, compressed between the jaws, increases to the point at which it is equal to the pressure being applied. At this point, there is a narrow, thin, compressed, double, layer of skin, wool and tissues between the jaws. This acts to keep the lamb castration clamp 100 on the lamb and seals off the scrotum from the lamb. Sealing helps to reduce any infection from the dead scrotum reaching the lamb. Once the clamping pliers and the lamb castration clamp have been held in the closed position for the required time, a rubber ring retaining element 108 is applied over the distal ends of the jaws 102, 104 using elastrator pliers. A check should then be performed to ensure that the lamb castration clamp is in the correct position on the scrotum, the clamping pliers are then removed, and the lamb released. On the lamb side of the lamb castration clamp 100, there is a junction between living skin with associated tissues, and the dying/dead compressed skin and tissue trapped between the jaws. At this junction, break-down and healing of the skin and tissue occurs. Using the lamb castration clamp 100 and clamping pliers 610 to apply a pressure of 7-16 MPa to the scrotums of 1-2 week old lambs, break-down and healing of the skin and tissues has been observed to occur in 10-14 days. The rate of breakdown is dependent upon various factors including the strength/thickness of the trapped skin i.e. how much it is compressed, and the breakdown of the tissues by the lambs healing processes as the dead skin is sloughed off and new skin grows in to form a continuous layer to bridge the 'fold' and form a scar. Use of the lamb castration apparatus has been observed to reduce the length time lambs experience acute pain during castration from hours, when castration is performed using the prior art rubber rings, to less than one minute. This is because conduction of nociceptor activity (pain signals), by nerves from the scrotum and testes to the brain, is rapidly blocked during application of the lamb castration clamp using the clamping pliers. Using the clamping pliers, the lamb castration clamp may be applied as easily, quickly and reliably as a rubber ring. As compared with castration using the prior art Burdizzo castration device, the lamb castration apparatus of the present invention, advantageously, requires less skill to reliably obtain effective castration and takes less time to perform, because the Burdizzo device must be applied at least once to the right spermatic cord and at least once to the left spermatic cord, whereas the lamb castration clamp can be applied in a single action, using the clamping pliers.

Claims

1. A lamb castration clamp (100, 200, 300) comprising: a pair of jaws (102, 104, 202, 204), each jaw comprising an inner contact surface (110, 310) and an outer engagement formation (112, 212) configured for engagement by clamping pliers for compressive force to be applied to the jaws by the clamping pliers, wherein the inner contact surfaces have a length of 50-70 mm and a width of 0.2-2 mm and are configured to engage each other along their entire length; hinge apparatus (106) connecting proximal ends of the jaws such that the opposing contact surfaces are in alignment and the jaws are movable by a compressive force from an open position, in which the jaws are spaced apart to receive the neck of the scrotum of a lamb, to a closed position, in which the jaws are close together so that the opposing aligned contact surfaces crushingly clamp the spermatic cords and nerves in the neck of the scrotum so as to stop blood flow to the scrotum and block conduction of nociceptor activity by the nerves; and a retaining element (108) configured to retain the jaws in the closed position.

2. A lamb castration clamp as claimed in claim 1, wherein the contact surfaces (110) have a width of 0.2-0.5 mm.

3. A lamb castration clamp as claimed in claim 1, wherein the contact surfaces (110) have a width of 0.5-2mm and the engagement formations define engagement slots (114, 214) for receiving complementary engagement formations provided at the distal ends of the jaws of clamping pliers.

4. A lamb castration clamp as claimed in any of claims 1 to 3, wherein the hinge apparatus(106) comprises a hinge barrel mounted in hinge socket and an elastically deformable retaining element configured to generally retain the hinge barrel within the hinge socket, while allowing movement of the hinge barrel within the hinge socket.

5. A lamb castration clamp as claimed in any preceding claim, wherein the retaining element and/or the elastically deformable retaining element comprises at least one elastically deformable ring (108).

6. A lamb castration clamp as claimed in any preceding claim, further comprising a pair of guide arms (120) provided on one jaw such that the inner contact surface of said jaw is located generally between the guide arms, the guide arms are configured to align the inner contact surfaces of the jaws in the closed position and to help gather and retain the tissues of the neck of the scrotum as the jaws are closed.

7. A lamb castration clamp as claimed in any preceding claim, wherein at least the jaws are formed from a biodegradable material.

8. Lamb castration apparatus comprising: double-lever, over-centre clamping pliers having an over-centre toggle, the clamping pliers comprising plier jaws and operating handles, the plier jaws being movable between an open position and a closed position by the operating handles; and a lamb castration clamp as claimed in any of claims 1 to 7, wherein the plier jaws comprise engagement formations at their distal ends, the engagement formations configured to engage the engagement formations of the lamb castration clamp such that the jaws of the lamb castration clamp are moveable from the open position to the closed position by a compressive force applied by the plier jaws moving from the open position to the closed position.