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Note: This page describes GENERAL PRINCIPLES of Euthanasia for WILDLIFE CASUALTIES. and other non-domestic animals. This page was originally written for the "UK Wildlife: First Aid and Care" volume of Wildpro, therefore specific information is included on euthanasia of UK wildlife species. This page has also been linked to from other Wildpro volumes and information has been added on the euthanasia of bears. Use the "Back" button on your browser toolbar to return to the last page you visited.

Introduction and General Information

Definition:

  • “Euthanasia” is the term used to describe the killing of animals in a humane manner, with absent or minimal pain or distress (mental suffering).
  • Techniques used for euthanasia should cause rapid loss of consciousness followed by cardiac and/or respiratory arrest and ultimately irreversible loss of brain function. (J4.218.w1)
  • It is essential that death is confirmed after euthanasia (by examination to ensure that vital signs such as heart beat, breathing, corneal reflexes and deep pain reflexes have ceased) before disposal of the body of the animal.
  • Animals in deep anaesthesia, for example, may appear dead but recover after a prolonged period.
  • The criteria required for confirmation of death may vary with the species of animal and the method of euthanasia used.

(B36.5.w5, B375.2.w2, J4.218.w1, J83.30.w1, J83.30.w2, D65)

It has been suggested that "The primary criteria for euthanasia in terms of animal welfare are that the method be painless, achieve rapid unconsciousness and death, require minimum restraint, avoid excitement, is appropriate for the age, species, and health of the animal, must minimise fear and psychological stress in the animal, be reliable, reproducible, irreversible, simple to administer (in small doses if possible) and be safe for the operator, and, so far as possible, be aesthetically acceptable to the operator." (J83.30.w1)

Situations requiring the use of euthanasia

  • Euthanasia is appropriate for animals which have been critically injured or are terminally ill. (B345.2.w2)

Euthanasia may be appropriate for wildlife casualty animals which:

  • Are in severe pain or distress.
  • Have injuries which would require treatment or care involving an unacceptable level of pain and distress.
  • Have injuries which would prevent return to the wild, and for which there is no appropriate long-term captive or semi-captive accommodation.
  • Are a danger to other animals or humans.
  • Require treatment/facilities which are not available, or which would be available only following transport which would cause unacceptable pain or suffering, or which would be available only following transport and such transport is not available/feasible.
  • In some circumstances involving a flock/group problem, euthanasia of a small number of ill animals may be required in order to provide a diagnosis allowing appropriate treatment of the remainder of the flock or group.

N.B. It must be acknowledged that, although there are some cases in which almost all people would agree on the need for euthanasia, people will vary in their decisions in many cases, due to differing opinions regarding, for example, the level of treatment through which it is appropriate to put a wild animal, and the suitability or otherwise of available long-term accommodation.

Methods:
  • Some methods of euthanasia which may be considered generally acceptable and preferred in most circumstances may require specialised equipment and/or training of personnel.
  • Some methods of euthanasia are acceptable in terms of the level of pain and stress to the animal but may:
    • Be aesthetically repugnant to some people;
    • Involve a possible health risk to personnel;
    • Involve a risk in terms of disposal of carcasses.
  • Some methods are acceptable in animals which are unconscious, or in circumstances where preferred methods are not available.
  • Some methods of killing animals, such as drowning, are never acceptable as methods of euthanasia: they do not cause death in a manner which could be described as causing no or minimal pain and stress.
No one method of euthanasia is preferred for all species and in all situations. However in all instances the aim should be to provide immediate insensitivity of the animal to pain. (B36.5.w5) The appropriate method will vary depending on the size, age and type of animal, means of euthanasia available at a given time, and the abilities/training of personnel involved. In situations such as road traffic accidents with a wildlife casualty suffering from severe trauma, physical methods may be the most appropriate methods to relieve pain and suffering. (J4.218.w1)

Methods of euthanasia may be divided into two main types: physical and chemical.

  • Examples of physical methods:
    • Gunshot, cervical dislocation, decapitation, or a sharp blow to the skull (stunning) followed by exsanguination (bleeding out).
  • Examples of chemical methods (these involve introducing a toxic agent into the body by injection or inhalation):
    • Overdoses of anaesthetic agents, or carbon dioxide.
(B36.5.w5)
  • For animals in long-term human care, veterinarians generally use chemical methods which are effectively anaesthetic overdoses for euthanasia. (V.w5)

Handling and restraint for euthanasia:

  • See also: Wildlife Casualty Handling and Transport
  • Methods of euthanasia usually require some degree of physical control over the animal to minimise pain and distress in the animal, ensure the safety of the person carrying out the euthanasia, and sometimes also to protect other animals and other people.
  • Different methods of euthanasia may require different degrees of control and types of restraint.
  • The use of tranquillising or immobilising drugs may be required prior to euthanasia to avoid pain, injury or anxiety to the animal or danger to the person carrying out the euthanasia.
(J4.218.w1)

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Euthanasia Techniques

PHYSICAL METHODS

Properly used, physical methods are fast acting, painless, humane and practical and may result in less fear and anxiety than other methods. Skilled personnel and well-maintained equipment are essential for the appropriate use of most physical methods and training by experienced persons should be sought. Carcasses should be used for practise of techniques before personnel use such methods on conscious animals. Physical disruption of brain activity causes rapid loss of consciousness, however, exaggerated reflex muscular activity may occur following loss of consciousness which may be disturbing to onlookers or operators. (J4.218.w1)

Shooting to kill
  • Free-bullet firearms may be used. (D65)
    • The ownership and use of such weapons is tightly regulated under the Firearms Acts 1967-1997 in the UK. (D65)
    • Licences for the ownership and use of such firearms are issued through the local police. (D65)
    • These include pistols designed as humane slaughtering free-bullet pistols such as the Cash .32 calibre pistol. (D65)
  • Firearms should only be used by persons with experience with such weapons. (D65)
  • Precautions must be taken to avoid accidents when using free-bullet weapons:(D65)
    • Animals should be restrained if possible. (D65)
    • Any assistants should be standing in a safe place. (D65)
    • The shot should be fired towards soft earth in order to avoid ricochet. (D65)
  • Shotgun: this should be used from a distance of 1-2mn aimed at a point just behind the ear so that the shot penetrates the brain. (D65)
  • Rifle or pistol: should be held close to, but not in direct contact with the animal's head and should be directed at the brain. (D65)
  • Aim at the centre of an imaginary "X" connecting the eyes and ears on opposite sides of the head, with the muzzle as close to the animal as is feasible. If firing at a distance of less than 1 ft (30 cm), for an animal weighing less than 100 lb (45 kg), a 0.22 calibre bullet is adequate. Larger bullets are needed for larger animals with heavy skulls. (B345.2.w2)
  • If there is any doubt as to whether the shot has been effective in killing the animal a second shot should be fired and/or the animal's throat should be cut (the major vessels of the neck severed) with a sharp knife, to ensure that the animal dies from blood loss (exsanguination). (D65)
  • This is considered to be an effective and humane technique for euthanasia. (J83.30.w1)
  • Note: for safety reasons, all other persons present must stand behind the person shooting: bullets which hit bone may then continue along an unexpected path. (B345.2.w2)

Minimum recommended calibers:

The following information has been taken directly from: (D65)

  • Shotgun:
    • .410 or 20 bore for small animals (e.g. rabbits, cats, game birds, ferrets, otters, squirrels, hedgehogs, foxes, small dogs).
    • 16 bore for medium-sized animals (e.g. badgers, foxes, muntjac, geese, dogs, sheep).
    • 12 bore at close range in an emergency for large animals (e.g. red deer, seals, cattle, horses, pigs).
  • Rifles/pistols:
    • .22 rim fire (long rifle). Bullet weight 2g (30gr) for small animals (e.g. rabbits, cats, game birds, ferrets, otters, squirrels, hedgehogs, foxes, small dogs). (D65)
    • .22 centre fire. Bullet weight 3-3.7g (45-55gr) for medium-sized animals (e.g. badgers, foxes, muntjac deer, geese, dogs, sheep). (D65)
    • Permitted deer rifles/military calibre rifles. Bullet weight >6.5g (>100gr) for large animals (e.g. red deer, seals, cattle, horses, pigs). (D65)
  • N.B.
    • Maximum recommended ranges are 75m for rifles, 8-10m for shotguns. (D65)
    • Rifles and shotguns of higher caliber than those suggested above may be used. (D65)
    • In an emergency the use of less powerful weapons at close range (1-2m) may be required. (D65)
    • Whenever possible, soft-nosed or hollow-nosed rifle bullets which expand on impact should be used. (D65)
Stunning with a cartridge-fired captive bolt pistol, followed by killing
  • Useful in field situations and where free-bullets must not be used for safety reasons. (D65)
  • The correct calibre of captive bolt equipment and strength of cartridge must be used. Tables detailing the correct information should be consulted. (D65)
  • A correctly stunned animal collapses immediately. Often the hind legs are flexed, the body muscles contracted and the neck arched. This may be followed by some kicking movements of the legs. (D65)
  • In some animals the bolt will penetrate deeper parts of the brain and kill the animal outright. This does not occur in all cases and death must be ensured by:
    • Pithing (physical destruction of the lower part of the brain and spinal cord by means of a long thin rod, wire or needle introduced into the cranial cavity through the hole made by the captive bolt and moving it with a vigorous stirring action)(D65) or:
    • Exsanguination (cutting the animal's throat with a sharp knife, deeply so that all the major blood vessels -carotid arteries and jugular veins - are severed). (D65)

    (D65)

Stunning by a sharp blow to the back of the head, followed by killing
  • Used where a captive bolt pistol is not appropriate or is not available. (D65)
  • A blunt instrument such as a large spanner, a spade, a piece of timber or similar is used to strike a sharp blow to the back of the head. (D65)
  • Alternatively, if it is safe to pick the animal up and this can be done without causing additional suffering, the animal may be swung so that the back of its head strikes a solid object such as a fencepost, tree, kerbstone or wall. (D65)
  • In either case the action must be carried out with as much force as possible. (D65)
  • Loss of consciousness may be evaluated by loss of menace/blink reflex, pupillary dilatation and loss of coordinated movements. (J4.218.w1)
  • In some cases the blow will cause sufficient damage to the brain or severe the brain from the spinal cord and the animal will die. This does not occur in all cases. Death of the stunned animal must be assured by the use of an additional technique: (D65, J4.218.w1, J83.30.w1)
    • Exsanguination (cutting the animal's throat with a sharp knife, deeply so that all the major blood vessels -carotid arteries and jugular veins - are severed). (D65, J83.30.w1)
    • Repeated blows to the back of the head to completely destroy the brain. (D65, J83.30.w1)
    • Decapitation (e.g. using the edge of a spade). (D65)
    • Asphyxia by putting pressure on the windpipe. (D65)
Cervical dislocation
  • This is only suitable for small animals which can be handled easily (e.g. rabbits, chickens). (D65)
  • May be carried out by a sharp blow to the back of the head to break the spinal cord or (D65)
  • May be carried out by traction: This requires practice and training on dead animals. (D65)
  • Death must be ensured by further blows or exsanguination. (D65)

    (D65)

Decapitation
  • Decapitation is not a commonly applicable method of euthanasia by itself, although it may be used to ensure death following the employment of other techniques such as stunning.
  • Decapitation may be suitable for use in a research setting, in appropriate species, with well-maintained equipment operated by properly trained personnel who are correctly informed regarding the health and safety risks of the method. (J4.218.w1)
  • May be suitable for small mammals if a specially designed guillotine is available. (J83.30.w1)
    • Research indicates that although electrical activity continues in the brain for 13 to 14 seconds after decapitation of small mammals loss of consciousness is rapid.
  • Is not suitable for reptiles or amphibians unless the animal has been stunned or otherwise rendered unconscious first, since they are very tolerant of anoxia. (J83.30.w1)
  • Is not suitable for birds. Research indicates visually evoked responses may continue for as long as 30 seconds after decapitation. (J83.30.w1)
Electrocution
  • This is used for stunning of some species in slaughterhouses. (D65)
  • Specialised equipment is required. (D65)
  • Electrocution is not a viable method of emergency killing in the absence of this specialised equipment. (D65)
Exsanguination
  • This is acceptable for euthanasia only in an animal which is already unconscious, as extreme hypovolaemia in a conscious animal causes stress, and pain may result from cutting of the deeper blood vessels. (J4.218.w1, J83.30.w1)
Hyperthermia
  • Excessive heat is lethal to all animals. (D65)
  • This is not recommended as a method of euthanasia for vertebrates. (D65)
  • Not an acceptable method of euthanasia. Dropping an animal into boiling water causes intense pain and a slow death. (J83.30.w1)
  • Boiling may be the only practical method available for the killing of crustaceans but cannot be regarded as ideal. (D65)
Hypothermia
  • Extreme cold kills all animals. (D65)
  • The formation of ice crystals in the tissues of the live animal is likely to be extremely painful (J4.218.w1), J83.30.w1)
  • This is not an acceptable method of euthanasia (D65, J4.218.w1, J83.30.w1)
  • Placing poikilotherms (cold-blooded animals) in a low temperature (e.g. 4°C)  may facilitate handling for other forms of euthanasia by making the animal sluggish. (D65)
Anoxia and asphyxia
  • Depriving an air-breathing animal of air will kill it, however this is not recommended as a means of euthanasia for conscious animals. (D65)
  • Strangulation is slow and causes pain, undue anxiety and stress (J83.30.w1)
  • In an emergency in an unconscious animal asphyxiation by putting pressure on the windpipe is a quick and effective method of killing. (D65)
  • Fish will die from lack of oxygen once out of water when the gills dry they should be stunned by a blow to the back of the head before this method of killing is used. (D65)
  • Drowning is not an acceptable method of euthanasia; it is slow and the hypoxia causes severe stress and anxiety. Similarly removing fish or other gilled vertebrates such as tadpoles from the water is not acceptable for euthanasia. (J83.30.w1)
CHEMICAL METHODS
  • Overdose of an anaesthetic agent is the method of euthanasia commonly used by veterinarians.
  • Chemical euthanasia agents which are inhaled necessarily take some time to act, as the substance must reach a sufficiently high concentration in the air-exchange regions of the lung before the effect can occur. Whether an inhalational (gaseous) agent is suitable for use for euthanasia "depends on whether an animal experiences distress between the time it begins to inhale the agent and the time it loses consciousness." (J4.218.w1)
Chloroform
  • This may be available from chemists but is not necessarily easy to obtain.
  • Chloroform is toxic and liquid chloroform is highly irritant to skin, chloroform vapour is irritant to the eyes and nose. 
  • Chloroform should be used outdoors or in a well-ventilated room. (D65)
  • If used correctly chloroform causes little distress to the animal and is suitable for some small animals up to 1kg bodyweight. (D65)
  • It is best used in a specially designed chamber and strictly in accordance with the manufacturer's instructions. The lid of the chamber contains a compartment holding a cotton lint pad. A measured amount of chloroform is poured onto the pad and the air holes closed gradually until the animal loses consciousness, then completely shut until the animal is dead.
  • Chloroform may also be used with the animal inside a thick, preferably clear, polythene bag. (D65)
  • This is suitable for the killing of small wild animals which are already confined within a wire/mesh cage or a loosely-woven sack. (D65)
  • The animal's container is placed in the plastic bag, a wad of cotton wool or similar material is moistened with about 10ml (2-3 teaspoons full) of chloroform and the wad placed in the open mouth of the bag, taking care that no chloroform liquid touches or drips onto the animal. (Twice the amount may be required for a large bag). Once the animal is unconscious the bag is closed, tied securely and left for at least 15 minutes. (D65)
  • N.B. apparently-dead individuals may recover from the effects of chloroform therefore death must be confirmed by the onset of rigor mortis or ensured by a physical method before the carcass of the animal is disposed of. (D65)
Carbon dioxide
  • This is considered appropriate for certain species. (J4.218.w1)
  • This is suitable for the euthanasia of small animals such as rodents and small birds, but not for animals larger than guinea pigs or small rabbits. (D65)
  • An anaesthetic/euthanasia chamber may be used and filled using a carbon dioxide cylinder. (D65)
  • A regulated flow of gas into the chamber used for euthanasia is required; therefore compressed CO2 gas cylinders are recommended as the source of carbon dioxide. (J4.218.w1)
  • It is important to ensure that the chamber is filled sufficiently so that the animal cannot lift its head above the gas. (J4.218.w1)
  • Small animals placed into a container pre-filled with approximately 100% CO2 show few signs of distress and lose consciousness in 8-12 seconds. If placed into a 70:30 or 80:20 CO2:Oxygen mixture even less signs of distress are seen and consciousness is lost in about 15-25 seconds. (D65)
  • After about 45 seconds exposure to 100% CO2 for an additional 5 minutes is required to ensure death. If there is any doubt that death has occurred a physical method (see above) should be used. (D65)
  • In day-old chicks, CO2 "caused little distress to the birds, suppressed nervous activity and induced death within 5 minutes"; 60-70% CO2 and exposure for five minutes "appears to be optimal." (J4.218.w1)
  • In the absence of a suitable chamber, a large, strong clear plastic bag may be used. The bag is pre-filled with CO2 then the animal, inside its cage, is placed into the bag. The bag is then securely tied and left for five minutes. (D65)
  • Another alternative is to pre-fill a large plastic or metal dustbin (which may be lined with a large strong plastic bag) with CO2. The animal is placed inside and the bag securely tied or lid replaced and left for at least five minutes. (D65)
  • Carbon dioxide is not suitable for reptiles or amphibians as the time to effect is too long in these species. (J83.30.w1)
  • Breathing rate of reptiles and amphibia may be too slow for acceptable use. (J4.218.w1)
  • At 100% carbon dioxide severe dyspnoea and distress may result in conscious animals. (J83.30.w1)
  • Not suitable for neonates as these are relatively tolerant of carbon dioxide. (J83.30.w1)
  • Burrowing animals may be relatively resistant to carbon dioxide. (J4.218.w1)
  • Not suitable in diving species such as mink. (J83.30.w1)
  • Studies showed that in mink 70% CO2 induced loss of consciousness but did not kill the animals; higher concentrations were effective and produced rapid death (J4.218.w1).
  • In some animals (e.g. pigs) CO2 may cause distress on exposure to high concentrations. (J4.218.w1)
  • Maintain flow of CO2 for at least one minute after apparent clinical death. (J4.218.w1)
  • Death may be ensured by the use of an additional euthanasia technique. (J4.218.w1)
Overdose of other gaseous anaesthetics
  • Suitable as a method of euthanasia for animals weighing less than 7kg; the cost and difficulty of administration makes these agents less useful for larger animals. (J4.218.w1)
  • A variety of gaseous anaesthetic agents have been used for the purpose of euthanasia. (J4.218.w1)
  • It has been recommended that halothane is the preferred gaseous anaesthetic agent for euthanasia, followed in order by enflurane, isoflurane, sevoflurane, methoxyflurane and desflurane, with or without nitrous oxide (the use of nitrous oxide alone is not recommended). (J4.218.w1). Induction with methoxyflurane is unacceptably slow in some species. (J4.218.w1,)
  • "Occupational exposure to inhalant anaesthetics constitutes a human health hazard". (J4.218.w1)
  • Ether has been used for euthanasia for many years. However due to the risks associated with its explosive nature it is recommended that it be used only in carefully controlled situations which comply with locally appropriate health and safety regulations. (J4.218.w1)
    • Ether is irritant and the vapour is both potentially flammable and explosive. (D65)
  • Gaseous anaesthetic agents may be used via anaesthetic mask, euthanasia chamber, deep containers such as a household rubbish bin, or an airtight plastic bag. (D65)
  • The gaseous anaesthetic is used to ensure unconsciousness, after which the concentration of gas is increased and the air/oxygen supply stopped. (D65)
  • Halothane is quick acting and stress-free. (J83.30.w1)
  • Enflurane is quick-acting and stress-free. (J83.30.w1)
  • Isoflurane is quick-acting and stress-free but the pungent odour may cause breath holding therefore it is not suitable for species with a large breath-holding capability. (J83.30.w1)
  • Neonates (new-borns) have a higher tolerance for hypoxia and may take longer to die with inhalational agents than do adults; other methods may be preferred. (J83.30.w1)
  • Reptile may hold their breath for long periods resulting in unacceptably slow induction. (J83.30.w1)
Overdose of an injectable anaesthetic drug
  • This method is commonly used by veterinarians for euthanasia of most animals.
  • Some authors consider this to be "the method of choice when a veterinary surgeon is available to perform or supervise the procedure." (D65)
  • Loss of consciousness is rapid and followed by death from respiratory and circulatory failure. (D65)
  • Route of injection: intravenous or intraperitoneal routes are used. (D65)
  • The needle used must be sufficiently small and sharp to penetrate the skin painlessly but sufficiently large to allow rapid safe injection of the required volume of drug. (D65)
  • Intracardiac injections are painful and should be used only on an animal which is already unconscious. (D65, J83.30.w1)
  • The most commonly used drugs for euthanasia by injection are the barbiturates, particularly pentobarbitone (pentobarbital).
  • Animals which cannot be handled to allow intravenous or intraperitoneal injection may be immobilised in a restraint cage or sedative or immobilising drugs used. (D65)
  • Care must be taken that the carcass is disposed of safely to avoid its being eaten by humans or by scavenging carnivores.
  • Pentobarbital (sodium pentobarbitone):
    • This is the most commonly used euthanasia drug.
    • Available as a soluble powder or as a sterile solution for anaesthesia (e.g. Nembutal, Sagatal) or as a non-sterile concentrated solution for euthanasia (e.g. Euthatal, Lethobarb). N.B. in the UK these are controlled drugs under Schedule 3 of the Misuse of Drugs Regulations 1985; they are not available to the general public. (D65)
    • Acts by depression of the central nervous system and causes cardiac arrest and respiratory arrest. (J83.30.w1)
    • For animals the size of a cat or dog, intravenous injection of 0.7ml/kg of 20% pentobarbitone solution is recommended. (D65) Anaesthesia occurs in 5-10 seconds and death shortly afterwards.
    • The intravenous route is also suitable for the euthanasia of larger species. (D65)
    • For smaller mammals and other vertebrates intraperitoneal injection of 1.0ml/kg of 20% pentobarbitone solution is recommended. (D65)
      • May cause irritation at the injection site with transient pain and distress. (J83.30.w1)
      • Occasionally an individual may show excitement before loss of consciousness. Such animals should be restrained or placed in a cage in a darkened room. (D65)
    • If the dose given is too low, deep narcosis rather than death may occur. Careful examination is required; if heartbeat or respiration have not ceased an additional dose of anaesthetic may be given (intraperitoneal or intracardiac) or a physical method (see above) may be used to ensure that death has occurred. (D65)
    • Death is faster with intravenous than intraperitoneal injection, but may require more handling which may result in more stress to the animal. (J83.30.w1)
    • A terminal gasp may occur, after the animal is unconscious, which may be aesthetically objectionable to some people. (J4.218.w1)
    • Care must be taken that the carcass is disposed of safely to avoid its being eaten by humans or by scavenging carnivores.

MS222 (Tricaine methane sulphonate) 

  • Suitable for fish and amphibians. (J4.218.w1)
  • Dissolved in water. 0.33mg/ml (1:3000) to induce anaesthesia, then increase the strength of the solution to 1mg/ml (1:1000). (D65, J83.30.w1)
  • Neutralise the acidity by buffering with e.g. sodium bicarbonate to give a solution pH 7.0-7.5 to reduce irritation. (J4.218.w1, J83.30.w1)
Potassium chloride
  • This is not suitable for use in conscious animals. 
  • Injection may result in "gasping, vocalisations, muscle spasms and convulsive seizures". (J83.30.w1)
  • It may be useful in animals which are at a surgical plane of anaesthesia, injected intravenously or intracardially.
    • It may be used in the field to reduce the risk of secondary poisoning of scavengers where disposal of the carcass of an anaesthetised animal is not assured. (J4.218.w1)

Euthanasia Techniques - Mammal Considerations
(The species-specific sections should be read in association with the general euthanasia section above)

Mammal Considerations
Badgers
  • Restraint in a trap or net may be required. (D65)
  • Frontal head shot using a .22 rifle or pistol. (D65)
  • Pentobarbital intraperitoneal injection has been suggested by some authors, preferably preceded by suitable sedative/ general anaesthetic for restraint. (D65) [The intravenous route of injection is preferable when possible]
  • Halothane inhalation. (D65)
  • For severely disabled or netted badgers physical methods may be used: very hard blows to the back of the head are required for this thick-skulled species, followed by exsanguination or pithing to ensure death has occurred. (D65)
  • N.B. It is essential that death is confirmed after euthanasia. Whenever the carer is not certain that death has occurred, additional techniques must be used to ensure death. (See introduction to this page).
Bats
  • Pentobarbitone by intraperitoneal injection. (D65)
  • Halothane overdose by inhalation. (D65)
  • Carbon dioxide in either a plastic bag or a bin. (D65)
  • Physical methods are appropriate for rapid killing if the animal appears to be suffering.
    • Place the bat on a flat hard surface, put a pencil across its neck, press firmly down on the pencil to crush the vertebrae and break the neck. (D65)
    • OR: Press the ribs firmly between thumb and forefinger to compress its ribs and cause a sudden stop in both heartbeat and breathing. (D65)
  • N.B. It is essential that death is confirmed after euthanasia. Whenever the carer is not certain that death has occurred, additional techniques must be used to ensure death. (See introduction to this page).
Bears
  • In a controlled setting, a chemical method of euthanasia can be used, preferably in a quiet, calming environment to minimise stress and distress. (D281.20.w20)
  • Use a chemical euthanasia solution commonly used and approved for domestic animals, at a dose rate at least equal to the suggested dosage for the weight of the individual, injected intravenously. (D281.20.w20)
    • Confirm the time of death e.g. by cardiac auscultation. (D281.20.w20)
    • Note: In a remote field situation, particularly with frozen ground, disposal of a large carcass following chemical euthanasia may be a problem. (D281.20.w20)
  • In an anaesthetised individual only, potassium chloride can be used for euthanasia. This is mixed with any fluid and shaken. About 30-60 mL of the resultant saturated salt solution is drawn up into a large syringe and injected intravenously into a large vein. This should cause cardiac arrest within 30 seconds. Muscle spasms may occur due to electrolyte changes in muscles. (B486.11.w11)
  • Alternatively, anaesthesia may be induced by chemical means then a physical method may be used. (D281.20.w20)
  • In a free-ranging or emergency situation, the method used should minimise stress and be as quick and humane as possible while protecting people and other animals. (D281.20.w20)
  • Adult bears are large, dangerous carnivores. The AAZV "Guidelines for Euthanasia of Nondomestic Animals" suggests that If it is necessary to shoot a charging bear at close range, "a repeating 12-gauge shotgun with a magnum load of 00 buckshot or slugs is preferred. A large caliber rifle is also acceptable, but is more often used in field situations for longer range shooting that can be quite precise when done by the right individual. Large caliber pistols can be useful, but for accuracy and charge stopping force, rifles or shotguns are preferred, with short-barrelled shotguns being more maneuverable in a situation where an animal may charge." (D281.20.w20)
    • N.B. "Local ordinances regulating possession and use of firearms must be adhered to and all protocols should try to maximise the welfare of the animals. That said, human safety should always be the primary consideration." (D281.20.w20)
    • For the most humane shooting, a head shot is recommended. Aim slightly off the centre of an imaginary "X" connecting the eyes and ears on opposite sides of the head, with the muzzle as close to the animal as is feasible. Place the shot as close as possible to perpendicular to the skull. Note that if the bullet is fired at too shallow an angle it may bounce off the skull. Larger bullets (> 0.22- caliber) are needed for large animals with heavy skulls, such as bears. (B345.2.w2, B486.11.w11)
    • Under AVMA guidelines, other placement of gunshot (neck, heart or lung shots) are not considered humane. (B486.11.w11)
  • Note that gunshot to the brain is not appropriate if there is a possibility of the individual being rabid, since the brain must be preserved to check for rabies. (D281.20.w20)
  • Exsanguination (bleeding) may be used in an anaesthetised large mammal. This can be carried out by severing the jugular vein and carotid artery, or by severing the femoral artery. (B486.11.w11)
  • N.B. It is essential that death is confirmed after euthanasia. Whenever the carer is not certain that death has occurred, additional techniques must be used to ensure death. (See introduction to this page).
Deer
  • "A severely injured or diseased animal should be killed without delay, using any readily available rifle or shotgun rather than waiting for one prescribed by law." (D65)
  • An injured animal may be immobilised using ropes/nets. (D65)
  • The use of dart guns is controlled under the Firearms Acts 1968-1997. (D65)
  • Stunning with a captive bolt or shooting with a free-bullet pistol may be used, aiming at a point intersecting two imaginary lines drawn from the base of each antler to the bottom of the opposite eye. (D65)
    • Exsanguination should be used to ensure that death has occurred. (D65)
  • An appropriate rifle (permitted deer rifles/military calibre rifles; bullet weight >6.5g (>100gr)) or shotgun (12 bore at close range in an emergency ) can be used. (D65)
    • At close range shoot from the side through the head aiming behind the eyes and ears.
    • At longer range (but preferably below 100m), shoot through the chest with a rifle and kill with a close shot to the head. (D65)
    • Exsanguination should be used to ensure that the animal is dead. (D65)
  • Intravenous pentobarbitone. (D65)
  • Preceded by immobilisation using ropes, nets or remotely delivered (darted) suitable sedative/general anaesthetic, as required. (D65)
  • Safe disposal of the carcass is required, ensuring that it is not eaten. (D65)
  • N.B. It is essential that death is confirmed after euthanasia. Whenever the carer is not certain that death has occurred, additional techniques must be used to ensure death. (See introduction to this page).
Foxes
  • Shooting at close range using a .22 rifle, or a 20 bore or .410 shotgun (for foxes in a trap, net or snare). A .22 centre-fire rifle or a 12 bore shotgun may be used at longer range. N.B. in urban areas it is necessary to consult the police before using firearms. (D65)
  • Pentobarbitone by intravenous, intraperitoneal or intracardiac injection, after immobilisation using a suitable sedative/ general anaesthetic. (D65)
  • N.B. It is essential that death is confirmed after euthanasia. Whenever the carer is not certain that death has occurred, additional techniques must be used to ensure death. (See introduction to this page).
Hedgehogs
  • Some authors suggest shooting with a shotgun or rifle. (D65)
  • Pentobarbitone overdose. (D65)
  • Halothane overdose. (D65)
  • Chloroform in a chamber or a plastic bag. (D65)
  • A sharp blow to the top/front of the head. (D65)
  • N.B. It is essential that death is confirmed after euthanasia. Whenever the carer is not certain that death has occurred, additional techniques must be used to ensure death. (See introduction to this page).
Moles
  • Pentobarbitone overdose. (D65)
  • Halothane overdose. (D65)
  • Chloroform in a chamber or plastic bag. (D65)
  • A sharp blow to the back of the head or strike the head of the animal on a hard edge such as the edge of a table. (D65)
  • N.B. It is essential that death is confirmed after euthanasia. Whenever the carer is not certain that death has occurred, additional techniques must be used to ensure death. (See introduction to this page).
Otters
  • Shoot with a 20 bore shotgun or a .22 rifle aiming to penetrate the brain. (D65)
  • Pentobarbitone by intraperitoneal injection, preceded if necessary by intramuscular or subcutaneous injection of a suitable sedative/general anaesthetic for immobilisation. (D65) [The intravenous route of injection is preferable when possible]
  • A sharp blow to the back of the head. (D65)
  • N.B. It is essential that death is confirmed after euthanasia. Whenever the carer is not certain that death has occurred, additional techniques must be used to ensure death. (See introduction to this page).
Rabbits and Hares
  • Pentobarbitone by intravenous or intraperitoneal injection. Ensure the carcass is disposed of safely and not eaten. (D65)
    • Intravenous pertobarbital is the method of choice; the lagomorph can be sedated first. (B284.10.w10)
    • With intraperitoneal injection, onset of action is fast if the drug is injected intrahepatically or intrarenally. (B284.10.w10)
  • Shoot with a shotgun or a .22 rifle. (D65For use in the field.
  • Halothane overdose. (D65)
  • A blow to the back of the head. (B284.10.w10, D65)
    • Note: this method requires experience to be effective. (B284.10.w10)
    • Hold by the hind legs in one hand and use the edge of the other hand, or a heavy stick, "priest" or poultry stunner to strike the back of the head; or
    • Place the rabbit on a flat surface such as a table, lift by the ears just enough so that the forepaws are off the table, then hit it hard behind the ears using a heavy object. (D65)
    • Pick up by the hind quarters and swing so that the back of the head hits a post, kerbstone or other hard surface. This is suitable for use in an emergency only.
    • Note: Exsangination (bleeding out), or asphyxiation by constricting the windpipe, should be used to ensure death. (D65)
    • Not suitable for use in a veterinary practice where other methods (chemical) are available. (B284.10.w10)
  • Cervical dislocation. (B284.10.w10)
    • Hold the hind legs in one hand and the head in the other hand with the thumb of that hand pressing against the back of the animal's head. Stretch the animal's body and at the same time pull and twist its head backwards and upwards so that the neck is broken. This method is recommended for use by persons with the necessary skill. (D65)
    • Loss of consciousness is immediate once the neck is broken and death is rapid but the animal may kick for a few minutes. (D65)
    • Note: this method requires experience to be effective. (B284.10.w10)
    • Not suitable for use in a veterinary practice where other methods (chemical) are available. (B284.10.w10)
  • N.B. It is essential that death is confirmed after euthanasia. Whenever the carer is not certain that death has occurred, additional techniques must be used to ensure death. (See introduction to this page).
Mice, voles, rats, dormice
  • Pentobarbitone by intraperitoneal injection. (D65)
  • Gaseous anaesthetic overdose with the animal in an anaesthetic chamber, or in a small mesh cage within a clear plastic bag. (D65)
  • Chloroform. (D65)
  • Carbon dioxide by exposure to 100% concentration in a chamber. (D65)
    • Confirm death by rigor mortis or ensure by exsanguination. (D65)
  • Hold on a table or similar surface and use a spanner or similar object to strike a sharp blow to the back of the head (if the animal is within a bag, manoeuvre so the head is pushed into a corner of the bag). (D65)
  • Hold by the body and swing the animal sharply so the back of its head strikes a hard edge such as the edge of a table. (D65)
    • Exsanguination should be used to ensure death. (D65)
  • For mice: Cervical dislocation. Place on a flat, non-slip surface and hold by the tail. As it pulls away, place a pencil, stick or similar object over the head close to the neck. Press down on the pencil to hold the head and pull the tail firmly until you feel the neck break. (Death is rapid but the animal may jerk for a few seconds). (D65)
  • Shooting: Suitable for rats. Use a shotgun, .22 rifle or a high-powered .22 air rifle. (D65)
  • N.B. It is essential that death is confirmed after euthanasia. Whenever the carer is not certain that death has occurred additional techniques must be used to ensure death. (See introduction to this page).
Seals
  • Shoot with a free-bullet pistol or revolver, aiming at the side of the head at a point midway between the eye and the ear. (D65)
  • Shoot with a rifle or shotgun. If shooting at a distance is necessary a heavy calibre rifle is needed. A shotgun may be used at point-blank range for euthanasia if necessary.
  • Pentobarbitone 200mg/ml intraperitoneal (a long needle is needed in a fat animal) or intravenous (about 10ml for a common seal pup and 15-20ml for a grey seal pup). Suitable sedative/ general anaesthetic may be used by any route for preliminary immobilisation.
  • Stun/kill: for seal pups. A heavy piece of wood about 1 metre long, such as a pick handle, should be used aiming carefully at the side of the head. (D65)
  • Repeat the blow if necessary. (D65)
  • Ensure death by piercing the heart or nearby blood vessels (midline between the fore flippers) or cut the throat. (D65)
  • N.B. It is essential that death is confirmed after euthanasia. Whenever the carer is not certain that death has occurred, additional techniques must be used to ensure death. (See introduction to this page).
Shrews
  • Gaseous anaesthetic overdose in an anaesthetic chamber. (D65)
  • Chloroform. (D65)
  • Carbon dioxide. (D65)
  • Cervical dislocation. Place on a flat, non-slip surface and hold by the tail. As it pulls away, place a pencil, stick or similar object over the head close to the neck. Press down on the pencil to hold the head and pull the tail firmly until you feel the neck break. (Death is rapid but the animal may jerk for a few seconds). (D65)
  • Hold on a table or similar surface and use a spanner or similar object to strike a sharp blow to the back of the head (if the animal is within a bag, manoeuvre so the head is pushed into a corner of the bag). (D65)
    • Exsanguination should be used to ensure death. (D65)
  • Hold by the body and swing the animal sharply so the back of its head strikes a hard edge such as the edge of a table. (D65)
    • Exsanguination should be used to ensure death. (D65)
  • N.B. It is essential that death is confirmed after euthanasia. Whenever the carer is not certain that death has occurred, additional techniques must be used to ensure death. (See introduction to this page).
Squirrels
  • Gaseous anaesthetic overdose in an anaesthetic chamber. (D65)
  • Carbon dioxide in a chamber or within a cage in a plastic bag. (D65)
  • Chloroform. (D65)
  • Hold on a table or similar surface and use a spanner or similar object to strike a sharp blow to the back of the head (if the animal is within a bag, manoeuvre so the head is pushed into a corner of the bag). (D65)
    • Repeat as required to ensure the animal is unconscious. (D65)
    • Dislocate the neck to ensure death of the unconscious animal. (D65)
  • N.B. It is essential that death is confirmed after euthanasia. Whenever the carer is not certain that death has occurred, additional techniques must be used to ensure death. (See introduction to this page).
Stoats, weasels, polecats, pine martens, mink
  • Restrain using a net, sack, restraint cage or cat grasper if necessary. (D65)
  • Pentobarbitone given by intraperitoneal injection. A suitable sedative/ general anaesthetic may be used if necessary for restraint. (D65)
  • Animals in a trap may be killed with a high-velocity 0.22 air rifle, aiming to penetrate the brain; this is not recommended for mink. (D65)
  • A blow to the back of the head with a heavy blunt instrument may be used to stun/kill the animal. (D65)
    • Exsanguination should be used to ensure that the animal is dead. (D65)
  • Juveniles may be killed by cervical dislocation as for rabbits. This requires skill and training. (D65)
  • N.B. It is essential that death is confirmed after euthanasia. Whenever the carer is not certain that death has occurred, additional techniques must be used to ensure death. (See introduction to this page).
Whales and Dolphins

Informed and informative discussions regarding possible euthanasia techniques for cetaceans are available in:

  • BDMLR - Marine Mammal Medic Handbook - Title page
  • RSPCA - Stranded whales, dolphins and porpoises - Title Page
  • RSPCA - Stranded Cetaceans - Title page
  • The following techniques have been suggested:
  • Anaesthetic overdose with etorphine (Immobilon LA) using a long needle to inject into muscle or blubber.
    • Some authorities consider etorphine injection to be the method of choice for euthanasia of cetaceans. (D42)
    • 0.5ml per 1.5 metres body length for small cetaceans, 4ml per 1.5 metres body length for larger cetaceans. (D23, D42, D65)

    N.B. this drug is very hazardous and has caused fatalities in humans. It should be used only by a veterinary surgeon. The antidote must be immediately available and at least one other person on site must be trained in its use. Members of the public should be kept away and the carcass disposed of safely to avoid scavenger animals being poisoned. (D65)

  • In the absence of etorphine it may be possible to use intramuscular (ideally intramuscular but probably "intrablubber") ketamine followed by intravenous pentobarbitone into the tail fluke veins. (D65)
  • Intravenous injections require experienced personnel; intravenous injection may be inadvisable because of the potential risk of human injury from the tail stock. However it is suggested that safe restraint of small cetaceans(<50-60kg body weight) for intravenous administration of pentobarbitone solution into the caudal peduncle vein may be performed. (D23, D42)
  • Where drugs are not available for euthanasia, shooting may be appropriate for euthanasia of toothed cetaceans up to 3-4 metres in length. Shooting is not considered an appropriate technique for euthanasia in baleen whales because of the anatomy of their head and blowhole. (D42)
    • A gun calibre of not less than .30 and solid bullets of at least 140 grains have been recommended as requirements for euthanasia; hollow or soft bullets should not be used as they lose penetration more quickly. (D42)
    • The shot should be aimed through the blowhole at an angle of 45° down and back to an imaginary line running between the pectoral fins. (D23, D42)
    • An alternative is a shot aimed "slightly up from just above the centre of the ear-eye line where the bullet should penetrate the skin". (D23, D42)
    • Never fire when the barrel is in direct contact with the animal. This is extremely dangerous." (D23, D42)
  • Opinions vary regarding which methods of killing cetaceans, while not ideal for euthanasia of these species, may be acceptable in an emergency. Suggested options are noted below:

    • Some authorities consider that shotguns and .22 rifles are not acceptable for killing stranded cetaceans. (D14, D42)
    • Other authorities consider that a shotgun or a centre-fire .22 rifle may be conditionally acceptable for the euthanasia of some small cetaceans if preferred methods are unavailable. (D65, J4.218.w1)
    • The use of a free-bullet firing humane slaughtering pistol has also been described. (D65)
    • The use of explosives for euthanasia is not recommended since a humane death cannot be guaranteed with this technique. (D42)
    • Additionally, it has been suggested that if no other option is available the use of intravenous or intraperitoneal injection of succinylcholine in conjunction with potassium chloride, causing complete paralysis of the respiratory musculature and death by hypoxia, may be more humane than leaving a large stranded cetacean to suffocate over a longer period of hours to days. However this is not considered as an acceptable method of euthanasia (J4.218.w1 [EDITORS NOTE: The editors of Wildpro have included this description for the sake of completeness. However, we believe that the administration of succinylcholine should only be undertaken in extremely controlled conditions and usually as an adjunct to general anaesthesia for surgical purposes. We feel that the administration of an irritant solution in large volumes to a fully conscious whale is likely to take some time and should NOT be undertaken as described above.]
    • The majority of authorities in the UK consider that have suggested that leaving the animal to die naturally may be the most humane option for large whales. (D42, D14).
    • Other methods of humane euthanasia for large whales are needed and remain under review.
  • N.B. It is essential that death is confirmed after euthanasia. Whenever the carer is not certain that death has occurred, additional techniques must be used to ensure death. (See introduction to this page).
Wild cats
  • Preferably restrain in a squeeze cage to facilitate injection. (D65)
  • Suitable sedative/ general anaesthetic may be administered intramuscularly for restraint if required.
  • Pentobarbitone by intravenous injection or by intraperitoneal injection near the middle of the abdomen, taking care to avoid the bladder.
  • Halothane overdose by inhalation. (D65)
  • Chloroform for kittens only, not adult cats. (D65)
  • For cats which are severely injured/dying (e.g. following a road traffic accident). A sharp blow to the back of the head to stun/kill, repeating if necessary. (D65)
  • N.B. It is essential that death is confirmed after euthanasia. Whenever the carer is not certain that death has occurred, additional techniques must be used to ensure death. (See introduction to this page).

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Euthanasia Techniques - Bird Considerations
(The species-specific sections should be read in association with the general euthanasia section above)

Bird Considerations
BIRDS
  • Shoot with a shotgun. (D65)
  • Pentobarbitone by intraperitoneal injection or intravenous injection as appropriate. (D65)
  • Overdose of inhalation anaesthetic such as halothane in an anaesthetic chamber (for small birds). (D65)
  • Chloroform administered in a plastic bag for small birds. (D65)
  • Carbon dioxide in a bin or bag. (D65)
  • Dislocation of the neck: Requires practice on dead birds to learn the technique.  (D65) Should only be used by persons confident of their ability to perform the technique quickly and effectively. (J83.30.w1)
    • For poultry-size birds: hold the legs in one hand, at chest level. Hold the head in the other hand with the second and third fingers on the back of the head. Pull the head down sharply; at the same time twist the head backwards. (D65)
    • For chicks: hold the body in one hand. Hold the head in the other hand and twist the neck until you feel the head detach from the spine.
    • For geese: hold the goose on the ground so its stretches its neck out. A broom handle or similar is placed across the neck close to the head. Stand on the broom handle (one foot either side of the bird's head) and pull the bird's body sharply upwards. (D65)
    • Ensure death has occurred by exsanguination or destruction of the brain. (J83.30.w1)
    • Sedation or general anaesthesia prior to cervical dislocation is preferred if possible. (J83.30.w1)

    N.B. cervical dislocation does not always result in immediate unconsciousness in poultry. (J83.30.w1)

  • Stun/kill by using a hard object such as a spanner to strike the back of the neck and repeat as necessary, OR swing the bird so that the back of its head strikes a post or similar hard object. (D65)
  • For small birds: compress the chest firmly with the thumb and fingers to cause cardiac arrest. (D65)
    •  This is rapid and apparently painless but may be considered aesthetically unpleasant and the degree of distress caused to the bird is unknown. (J4.218.w1)
    • It may be useful in the field when other methods cannot be used. (J4.218.w1)
  • N.B. It is essential that death is confirmed after euthanasia. Whenever the carer is not certain that death has occurred, additional techniques must be used to ensure death. (See introduction to this page).

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Euthanasia Techniques - Reptile Considerations
(The species-specific sections should be read in association with the general euthanasia section above)

Reptile Considerations
REPTILES
  • Pentobarbitone has been given by injection into the peritoneal cavity (D65, J4.218.w1) or intravenous injection in larger species. (J83.30.w1)
  • Halothane or methoxyfluorane gaseous anaesthetic overdose has been used in an anaesthetic chamber (slow). (D65) These compounds may be irritant to the skin and this technique is not considered acceptable by some authors. (J83.30.w1)
  • Carbon dioxide: time to loss of consciousness may be prolonged. (J4.218.w1)
  • Stun/kill by using a hard object to strike the back of the head. Suitable for a disabled or anaesthetised animal. (D65, J83.30.w1)
  • For small lizards, pick the animal up by the body and swing the animal so that the back of its head strikes a post or similar hard object. (D65)
  • After stunning, the brain should be destroyed to ensure death. (J83.30.w1)
  • N.B. It is essential that death is confirmed after euthanasia. Whenever the carer is not certain that death has occurred, additional techniques must be used to ensure death. (See introduction to this page).

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Euthanasia Techniques - Amphibian Considerations
(The species-specific sections should be read in association with the general euthanasia section above)

Amphibian Considerations
AMPHIBIANS
  • Pentobarbitone injection into the peritoneal cavity (D65, J83.30.w1, J4.218.w1); may also be dissolved in water to be absorbed through the skin. Correct injection site and experienced handling are required to minimise stress. (J83.30.w1)
  • Gaseous anaesthetic overdose may be administered (e.g. halothane or methoxyflurane) in an anaesthetic chamber or plastic bag. These may also be dissolved in water to be absorbed through the skin. (D65) These compounds may be irritant to the skin and this technique is not considered acceptable by some authors. (J83.30.w1)
  • Carbon dioxide: time to loss of consciousness may be prolonged. (J4.218.w1)
  • Benzocaine, dissolved in acetone or alcohol and added to water to give a solution of 200 parts per million (200mg/l) will give rapid, deep anaesthesia. The animal should be left in the solution until death is ensured. (D65, J83.30.w1). The solution should be at least 250mg/ml. (J4.218.w1)
  • MS222 (Tricaine methane sulphonate) dissolved in water (0.33mg/ml (1:3000)) will induce anaesthesia. The strength of the solution should then be increased to 1mg/ml (1:1000). (D65, J83.30.w1)
    • the acidity may be neutralised to reduce irritation by buffering with sodium bicarbonate etc. to give a solution pH 7.0-7.5. (J4.218.w1, J83.30.w1)
  • Stunning followed by crushing of the skull: the hind quarters should be held and head struck against a hard surface with sufficient force to crush the skull, OR a solid object such as a spanner used to hit the top of the head with some force. For small animals the head may be held gently in place with a piece of wood and the blow then aimed at the wood over the head (giving a larger surface to aim at). (D65, J4.218.w1, J83.30.w1)
  • The brain should be destroyed once the animal is unconscious, to ensure death. (J4.218.w1, J83.30.w1)
  • Decapitation is acceptable only in animals which are already insensible (J83.30.w1) but may be used to ensure death e.g. following stunning. (J4.218.w1)
  • N.B. It is essential that death is confirmed after euthanasia. Whenever the carer is not certain that death has occurred, additional techniques must be used to ensure death. (See introduction to this page).

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UK Contact Organisations and Published Guidelines for Further Reading (Electronic Library)

ORGANISATIONS
(UK Contacts)
  • The majority of the organisations listed within the Wildlife Casualty Handling and Transport section may be able to provide assistance. Please check their details carefully for relevance to your enquiry before contacting them.

ELECTRONIC LIBRARY
(Further Reading)
Click image for full contents list of ELECTRONIC LIBRARY

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Authors & Referees

Author Debra Bourne
Referees Becki Lawson and Suzanne Boardman

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