The legislation covering the welfare of all farmed animals whilst being handled and slaughtered is The

Welfare of Animals (Slaughter or Killing) Regulations 1995 (as amended) (WASK ’95). This states

that:

”Any person engaged in the bleeding of any animal which has been stunned shall ensure that

the animal is bled without delay after it has been stunned.”

“.... any person engaged in the bleeding of any animal that has been stunned shall ensure that:

(a) the bleeding is rapid, profuse and complete

(b) the bleeding is completed before the animal regains consciousness 

(c) the bleeding is carried out by severing at least one of the carotid arteries or the vessels

from which they arise”

In addition, hygiene legislation introduced in 2006, Regulation (EC) No. 853/2004 - ‘H2’, requires that:

“(a) the trachea and oesophagus must remain intact during bleeding, except in the case of 

slaughter according to a religious custom.” 

Studies of the bleeding of animals following stunning have shown that it is essential to cut all major

blood vessels supplying the brain, rather than just one, to ensure death is caused by rapid blood

loss and before consiousness returns. 

The following diagram shows the variation in times to loss of brain function, as influenced by

the timing, quality and technique of sticking. In sheep, if only one carotid artery and one jugular

vein are cut (half-cut), brain death can take up to 70 seconds (over 50 seconds longer than with

a full cut). During this time the animal may enter the recovery phase and consciousness will return.

In pigs, a significant delay in bleeding will result in the animal possibly entering the recovery

stage before brain function is lost.

Stun-to-Stick Times (Electrical Stunning)

SUMMARY

Head-only electrical stunning is a reversible process; animals will recover if

they are not killed immediately after stunning by severing the major arteries

supplying the brain. 

For slaughter to be humane, it is essential that animals are stunned

effectively and bled correctly without delay (within 15 seconds) to ensure

death is caused by blood loss and that it occurs before the animal regains

consciousness. 

Bleeding effectively and within 15 seconds of head-only electrical

stunning is essential to ensure humane slaughter of animals. 

No.17

Legislation 

Physiology

Resumption of Consciousness

breathing returning

Stun 15 30 45 60 75 90

Sheep (half cut)

Sheep (chest stick)

Sheep (delayed full cut)

Sheep (full cut)

Recovery 

Clonic

Tonic

Clonic

Minimum duration of phase

Possible duration of phase

Start of bleeding Brain death

Time taken for brain death

to occur after bleeding

Pig (cut at 10 secs)

Pig (cut at 20 secs)

Pig (cut at 15 secs)

Humane Slaughter Association
When electrically stunned, an animal will pass through three stages: tonic, clonic and recovery. In

an abattoir situation the third should never be seen. 

Bleeding involves cutting the carotid arteries and the jugular veins, or the vessels from which they

arise. It is important that all blood vessels are cut cleanly to ensure that blood loss is rapid and

profuse. 

The chest stick is the most efficient method of bleeding for red meat species, as it severs all the major

blood vessels close to the heart. This achieves both rapid initial blood loss and the shortest time to

loss of brain function. 

For pigs, the knife should be inserted in the mid-line of the neck at the depression in front of the

breastbone. When penetration has been made, the knife handle should be lowered, so that the blade

is pointing towards the tail of the animal, and pushed upwards to sever all the major blood vessels

which arise from the heart.

For a rapid bleed out, and to comply with new regulations, it is recommended that sheep and goats

should be stuck close to the heart in a similar manner to pigs. Alternatively, sticking may be done by

making a deep, transverse cut across the throat close to the head, to sever the four major blood

vessels in the neck. However, if the slaughter is not according to a religious custom, this may result

in a non-compliance and will also result in a longer bleed out time. 

The Welfare of Animals (Slaughter or Killing) Regulations 1995 (as amended) HMSO 1995

Regulation (EC) No. 853/2004 - ‘H2’ HMSO 2006

Full details of all legislation can be found on www.legislation.hmso.gov.uk

Electrical Stunning of Red Meat Animals HSA 2005

June 2006

The Old School . Brewhouse Hill . Wheathampstead . Herts AL4 8AN

Tel: +44(0)1582 831919 Fax: +44(0)1582 831414 Email: info@hsa.org.uk Website: www.hsa.org.uk

Registered Charity No. 209563

Taking a rational, practical

approach, making real,

lasting improvements to the

welfare of food animals

The only charity committed

exclusively to the welfare of

animals in markets, during

transport and to the point of

slaughter

WARNING: DISCLAIMER OF LIABILITY

In no circumstances can the HSA accept liability for the way in which the information in this leaflet is used: or for any loss, damage,

death or injury caused thereby, since this depends on circumstances wholly outside the HSA’s control.

Signs of consciousness

Phase Duration Visible signs

Tonic 10 to 20 secs

• animal collapses

• body becomes rigid

• no rhythmic breathing

• head raised

• hind legs flexed into body

Clonic 15 to 45 secs • involuntary kicking or paddling

• relaxation

Recovery 30 to 60 secs

• resumption of normal rhythmic breathing

• responds to painful stimuli 

• becomes visually aware

• attempts to stand

Correct bleeding

Further reading

After stunning, it is essential that animals are bled without delay (within 15 seconds) so

there is no chance of consciousness returning before death occurs.