**8. Local anesthesia for husbandry procedures in farm animals**

Some of the husbandry objectives are met by practices that are painful for the animals concerned. The behavioural and physiological responses, and by inference the pain, caused by particular husbandry procedures may be reduced by choosing methods that cause less pain, by carrying out the procedures in young rather than older animals and by using painrelieving drugs, such as local anesthetics.

For each species several such practices may be carried for different reasons: to minimize the risk of injury to animals and people (e.g. dehorning); to reduce aggressive behaviour and make male animals easier to handle (e.g. castrating oxen); to prevent carcass damage such as bruising (e.g. dehorning); to enhance carcass quality (e.g. castration); to prevent damage to the environment (e.g. nose ringing in pigs); to aid in identification (e.g. ear marking or notching, branding);

The needle must be gently manipulate anteriorly until its point passes medially around the coronoid process, then advanced to the pterygopalatine fossa rostral to the solid bony plate that is in close proximity of the orbitorotundum foramen. Following aspiration, 7–15 ml of

Oculomotor, trochlear, abducens, and three branches of the trigeminal nerve (ophthalmic,

Brachial plexus block is suitable for inducing analgesia for the surgery on the front limb, any

Brachial plexus block is relatively simple and safe to perform and produces selective

This technique places a local anesthetic in close proximity to brachial plexus nerves that

Gradual sensation and loss of motor function occurs within 10-30 minutes depending on the type of drugs used. Anesthesia lasts for approximately 2-6 hours, and total recovery requires

A 20-22 gauge spinal needle is inserted medial to the shoulder joint and directed parallel to

In large size animal, if no blood is aspirated into the syringe as the needle is withdrawn, approximately 10-15 ml of 2% lidocaine or 0.5 % bupivacaine at 3 mg/kg with dilution up to

Local anesthetics are injected to brachial plexus which would diffuse into the area to effect.

Some of the husbandry objectives are met by practices that are painful for the animals concerned. The behavioural and physiological responses, and by inference the pain, caused by particular husbandry procedures may be reduced by choosing methods that cause less pain, by carrying out the procedures in young rather than older animals and by using pain-

For each species several such practices may be carried for different reasons: to minimize the risk of injury to animals and people (e.g. dehorning); to reduce aggressive behaviour and make male animals easier to handle (e.g. castrating oxen); to prevent carcass damage such as bruising (e.g. dehorning); to enhance carcass quality (e.g. castration); to prevent damage to the environment (e.g. nose ringing in pigs); to aid in identification (e.g. ear marking or

maxillary, and mandible) are desensitized in 10–15 minutes following injection.

The technique should be performed in a well-sedated or anesthetized animal.

This block can be used in small ruminants, calves, and foals.

the vertebral column toward the costochondral junction.

anesthesia and relaxation of the limb and analgesia to the forelimb.

include the radial, ulnar, median, musculocutaneous and axillary nerves.

**8. Local anesthesia for husbandry procedures in farm animals** 

The brachial plexus nerves derived from C-6, C-7, C-8 and T-1 spinal nerves roots.

local anesthetics are injected.

**7.6.5 Brachial plexus block** 

approximately 6-9 hours.

20-30 ml is slowly injected.

notching, branding);

relieving drugs, such as local anesthetics.

area below distal part of humerus.

Cattle can be subjected to the following painful husbandry procedures: disbudding, dehorning, castration, branding and ear notching or tagging. In addition, some heifers may be spayed, and dairy cattle may have their tails docked.

Disbudding is used to mean the prevention of horn growth before it has become advanced, and dehorning means the amputation of horns at any stage after their growth has progressed beyond the early budding stage. Disbudding of calves at a very young age is recommended.

Cautery disbudding is preferable, but extreme escape behaviour of the calf shows that application of the hot iron is painful. This behaviour, and the often less obvious response that occurs with surgical disbudding, can both be eliminated using local anaesthetic blockade of the corneal nerve or a ring block around the base of each horn bud.

Removal of horns from mature cattle without anaesthetics is very painful. Dehorning mature animals may be more painful than most other procedures.

The behavioural response to the pain caused by the act of amputating the horn can be eliminated using local anaesthetic blockade of the corneal nerve or by a ring block around the horn base.

Effective cornual nerve blockade using local anaesthetic eliminates the initial peak of the plasma cortisol response and cortisol concentrations remain at pre-treatment levels for about 2 hours. Thereafter the concentrations increase for about 6 hours before returning to pre-treatment levels (McMeekan *et al*., 1998a).

This is interpreted to indicate that effective corneal nerve blockade eliminates pain for about 2 hours, after which some pain is experienced. This delayed pain is probably dull and not as acutely sore as the initial pain of horn amputation. To eliminate the acute cortisol response for at least 12 hours the dehorned animal needs to be given a systemic analgesic along with the local anaesthetic; a combination of an NSAID (non-steroidal anti-inflammatory drug) with a local anaesthetic is effective in this regard (McMeekan *et al*., 1998b; Stafford *et al*., 2003; Milligan *et al*., 2004; Stewart *et al*., 2009).

When local anaesthetic is given before dehorning, cautery of the wound to control haemorrhage also reduces the plasma cortisol response, and by inference the pain experienced by cattle, for at least 24 hours (Sutherland *et al*., 2002).

Castration is a standard husbandry practice in most cattle production systems and it is painful. The cortisol response to clamp castration is less than the response to rubber-ring or surgical castration, which suggests that the clamp is less painful (Stafford *et al*., 2002).

Local anaesthesia placed in the distal scrotum and testicles eliminates or reduces the painrelated behaviours seen at castration by these methods. It eliminates the plasma cortisol response to castration by rubber ring or band. This is because the tight ring or band stops blood and lymph perfusion of the testicles and scrotum so that the local anaesthetic remains in those tissues beyond the time required for anoxic death of the pain receptors and associated nerves.

Heifers are spayed to prevent mis-mating and to prevent mating of cull cows in extensive farming systems. The ovaries are removed either through the vagina in larger cows and

Local Anesthesia for Husbandry Procedures and Experimental Purposes in Farm Animals 247

Squirting local anaesthetic into the scrotal neck and on to the spermatic cords before they are severed towards the inguinal area may reduce the pain experienced by lambs following

Tail docking is carried out on woolly sheep. Local anaesthesia may be injected as a ring block around the tail (subcutaneously), but this is difficult and time consuming. The use of

Disbudding is carried out on young goats before the horn bud becomes too large. Local

Castration and ear tagging or ear notching and the use of analgesia are conducted in goats

The management of pigs ranges from intensive indoor to extensive outdoor approaches. Piglets are subject to a number of painful procedures including castration, teeth clipping, tail docking and, if they are going to live outdoors, rings may be inserted into their noses.

Traditionally, pigs have been castrated surgically. Local anaesthetics prevented pain-related behaviours in 2-week-old piglets, but not in 7- week-old piglets (McGlone & Heilman, 1988). Gaseous anaesthesia technology suited to pig farms is being developed and it may soon become normal to give piglets a general anaesthetic and then to castrate them, clip teeth and

Local anaesthesia and sedation could be used to reduce the pain caused by ring placement. Horse castration is carried out in many countries under general anaesthesia, or standing

Beak trimming is the most important amputation carried out on chickens and turkeys. Beak

trimming is acutely painful and food intake levels decrease following it (Glatz, 1987).

under sedation and with local anaesthesia (Ohme & Prier, 1974).

surgical castration where the spermatic cords are drawn out and broken by traction.

local anaesthetics greatly reduced behavioural indicators of pain (Kent *et al*., 1998).

Ear tagging or ear notching in sheep are similar to those carried out in cattle.

anaesthetic is often used when disbudding goats.

Fig. 5. Piglet castration

dock tails at one time.

in a manner similar to those used in cattle and sheep.

heifers following epidural anaesthesia or in smaller heifers through an incision in the flank. A flank incision is certainly painful and warrants local anaesthesia.

Fig. 4. Cautery disbudding in the calf

Tail docking young calves by rubber ring or cautery is not especially painful, and local anaesthetic either given as a tail ring block or an epidural can be used to alleviate the pain.

Ear tagging and is a common way of identifying individual animals. Ear tags or ear notches are used also to indicate the ownership of cattle. Little work has been done on reducing the pain caused by these procedures, and as it is not easy to anaesthetize the ears using local anaesthetic, systemic analgesia would be preferable.

Branding by hot iron or freeze branding are common means of identifying cattle both for ownership and for recognizing individual animals. Little work has been done on reducing the pain caused by these procedures.

As multiple injections of local anaesthetic in the area to be branded are impractical, systemic analgesia would probably reduce but not eliminate the pain experienced following branding.

The most common painful husbandry procedures used in sheep are castration, tail docking and ear tagging or notching. These procedures are generally carried out on lambs.

Local anaesthetic injected into the scrotum and testicles eliminates the plasma cortisol response and by inference the acute pain caused by rubberring castration (Dinniss *et al*., 1997). Kent *et al*. (1998) found that lidocaine injected into the neck of the scrotrum was more effective than injection into the testicles, but Dinniss *et al*. (1997) showed that intratesticular injections were just as effective but practically much easier to execute than scrotal neck injections.

Local anaesthetics have less impact on responses to surgical or clamp castration, and with these techniques a systemic analgesic such as an NSAID is required together with local anaesthesia to eliminate the pain caused by castration.

Squirting local anaesthetic into the scrotal neck and on to the spermatic cords before they are severed towards the inguinal area may reduce the pain experienced by lambs following surgical castration where the spermatic cords are drawn out and broken by traction.

Tail docking is carried out on woolly sheep. Local anaesthesia may be injected as a ring block around the tail (subcutaneously), but this is difficult and time consuming. The use of local anaesthetics greatly reduced behavioural indicators of pain (Kent *et al*., 1998).

Ear tagging or ear notching in sheep are similar to those carried out in cattle.

Disbudding is carried out on young goats before the horn bud becomes too large. Local anaesthetic is often used when disbudding goats.

Castration and ear tagging or ear notching and the use of analgesia are conducted in goats in a manner similar to those used in cattle and sheep.

The management of pigs ranges from intensive indoor to extensive outdoor approaches. Piglets are subject to a number of painful procedures including castration, teeth clipping, tail docking and, if they are going to live outdoors, rings may be inserted into their noses.

Fig. 5. Piglet castration

246 A Bird's-Eye View of Veterinary Medicine

heifers following epidural anaesthesia or in smaller heifers through an incision in the flank.

Tail docking young calves by rubber ring or cautery is not especially painful, and local anaesthetic either given as a tail ring block or an epidural can be used to alleviate the pain. Ear tagging and is a common way of identifying individual animals. Ear tags or ear notches are used also to indicate the ownership of cattle. Little work has been done on reducing the pain caused by these procedures, and as it is not easy to anaesthetize the ears using local

Branding by hot iron or freeze branding are common means of identifying cattle both for ownership and for recognizing individual animals. Little work has been done on reducing

As multiple injections of local anaesthetic in the area to be branded are impractical, systemic analgesia would probably reduce but not eliminate the pain experienced following

The most common painful husbandry procedures used in sheep are castration, tail docking

Local anaesthetic injected into the scrotum and testicles eliminates the plasma cortisol response and by inference the acute pain caused by rubberring castration (Dinniss *et al*., 1997). Kent *et al*. (1998) found that lidocaine injected into the neck of the scrotrum was more effective than injection into the testicles, but Dinniss *et al*. (1997) showed that intratesticular injections were just as effective but practically much easier to execute than scrotal neck

Local anaesthetics have less impact on responses to surgical or clamp castration, and with these techniques a systemic analgesic such as an NSAID is required together with local

and ear tagging or notching. These procedures are generally carried out on lambs.

A flank incision is certainly painful and warrants local anaesthesia.

Fig. 4. Cautery disbudding in the calf

the pain caused by these procedures.

branding.

injections.

anaesthetic, systemic analgesia would be preferable.

anaesthesia to eliminate the pain caused by castration.

Traditionally, pigs have been castrated surgically. Local anaesthetics prevented pain-related behaviours in 2-week-old piglets, but not in 7- week-old piglets (McGlone & Heilman, 1988).

Gaseous anaesthesia technology suited to pig farms is being developed and it may soon become normal to give piglets a general anaesthetic and then to castrate them, clip teeth and dock tails at one time.

Local anaesthesia and sedation could be used to reduce the pain caused by ring placement.

Horse castration is carried out in many countries under general anaesthesia, or standing under sedation and with local anaesthesia (Ohme & Prier, 1974).

Beak trimming is the most important amputation carried out on chickens and turkeys. Beak trimming is acutely painful and food intake levels decrease following it (Glatz, 1987).

Local Anesthesia for Husbandry Procedures and Experimental Purposes in Farm Animals 249

Local anaesthetic creams are generally ineffective when applied to intact animal skin because they are poorly absorbed. This has limited their use to topical anaesthesia of mucous membranes. To diffuse through nerve membranes the local anaesthetic must be in the form of the unchanged base, but formulations in which the lipid soluble free base

This problem has been overcome with a eutectic combination of lidocaine and prilocaine. When mixed together at room temperature crystals of these drugs form an oily liquid. No additional solvent is necessary, so droplets of an oil in water emulsion of lidocaine and prilocaine each have a concentration of 80% of active drug compared with the 20% of conventional formulations. The total concentration of local anaesthetic remains low at 5%. Lidocaine-prilocaine cream produces effective topical dermal anaesthesia. The advantages of avoiding painful needle punctures are selfevident. Not only is animal discomfort reduced

Pain associated with vessel puncture has long been accepted as an unavoidable consequence of blood collection and intravenous drug administration. The degree of pain associated with the procedure is believed to be minimal, provided that a fine gauge needle is used and that

In many instances, however, it is necessary to use larger gauge needles and this may produce a detectable reaction from the animal. Such responses are also noted more frequently when

When vessel puncture is undertaken by relatively inexperienced staff, repeated attempts may be necessary before the procedure is carried out successfully. Under these circumstances, the animal may experience greater pain or discomfort than when the

There has been considerable debate as to the nature of pain in animals, since it is unclear what form animal experiences may take. It has been suggested that one constructive approach is to accept that animals are capable of sensory experiences which, given the opportunity, they avoid and which modify their biochemistry, physiology, and behaviour in a species-specific way. Many of the stimuli that produce these reactions in animals would produce the sensation described as pain in man, and hence nociceptive reactions in animals such as withdrawal of the limb, vocalizations and aggressive behaviour may be interpreted

In human anaesthetic practice, it has been demonstrated that pain caused by the intravessel insertion of needles and cannulae can be alleviated by the topical application of local anaesthetic cream. The feasibility of using a similar technique in animals has been shown.

A commercially available local anaesthetic cream (EMLA®) can be used for application prior to vessel puncture in farm animals. EMLA cream consists of a eutectic mixture of lignocaine base (25 mg/ml) and prilocaine base (25 mg/ml), together with an emulsifier, a viscosity increasing agent and water and with the pH of the cream adjusted to pH 9,4 with

the animal is expertly restrained and the operator skilled in the technique.

over-the-needle type cannulae are inserted to provide long-term vascular access.

dissolves easily achieve poor penetration of unbroken skin.

but also the procedure is easier to carry out.

**11. Local anesthesia for vessel puncture** 

technique is undertaken by a skilled operator.

as one type of response to pain.

sodium hydroxide.

Behavioural and physiological evidence suggests that pain and beak sensitivity persists for weeks or months after trimming (Craig and Swanson, 1994). A local analgesic (bupivacaine and diethyl sulfoxide) administered to the cut beak of 6-week-old chicks after trimming prevents at least some of the acute pain and the reduction in feed intake usually seen in the first 24 hours after trimming.
