Pork FACS: Euthanasia in Pigs

Judicious use of euthanasia is essential to achieving appropriate animal welfare on pig farms. Humanely killing an animal on farm is a means of immediately ending unacceptable levels of pain and suffering due to an injury or disease. In less severe cases, euthanasia should be employed if an animal is no longer productive and is either unsuitable for salvage slaughter, or cannot be transported to slaughter without risking additional suffering. In choosing a procedure for euthanasia, producers must not only consider the welfare of the animal, but also the safety of their workers and the sustainability of the method to their individual operations. Producers should be aware of the options and develop an action plan to determine if euthanasia is appropriate and what method should be used for each age and size category of pig on their farm. Each farm should have the necessary equipment on hand to carry out its euthanasia protocol.

Blunt Trauma

A firm, sharp blow with a blunt object to the top of the head can be used to euthanise piglets less than 2 to 3 weeks of age. The blow must be delivered with sufficient force so as to prevent just stunning the animal. This method is unacceptable for larger animals. Stockpersons may find this procedure objectionable, in which case carbon dioxide may be an effective alternative.

Carbon Dioxide

The use of carbon dioxide is a recommended method for euthanasia of piglets and nursery pigs up to 32 kilograms (70 pounds). An alternative form of euthanasia is recommended for larger animals simply because of space limitations in euthanasia containers. A container with both an inlet and outlet valve is needed so that carbon dioxide can be pumped in while air can escape. This purpose is often served by a garbage can with valves located in the lid. Carbon dioxide is an effective euthanasia anaesthetic that causes an abrupt loss of consciousness and subsequent death due to respiratory arrest. This risk to humans is very low. Use of carbon monoxide (eg. exhaust gases) is not recommended due to the high risk it poses to humans.

Gunshot

While impractical in piglets due to their small size, this is often the only alternative for large boars and sows in the field. This method requires a high degree of accuracy to ensure correct placement and entry into the skull. The shot should be directed at the midline of the forehead, 2 cm (3/4 inch) above eye level and discharged 5 to 22 centimetres (2 to 10 inches) away from the skull. Penetration into the skull is necessary to kill the animal and in larger animals this method may only stun. In such a case, the procedure should be followed by exsanguination (bleeding). The risk to humans is high and this method should be considered a last resort in special circumstances. Firearm safety, including proper training and secure storage, must be of the utmost concern.

Captive Bolt Pistol

Like a gunshot, this method is dependent on concussive force and brain penetration. Normally the captive bolt pistol will only stun large animals due to limited brain penetration. In such a case, the procedure should be followed by exsanguination. Placement is the same as for a gunshot although the pistol is held firmly against the skull in this method. Proper restraint is of the utmost importance in the success of this method. Appropriate training in the safe use of the captive bolt is important.

Exsanguination or Bleeding

Bleeding an animal out by puncture of the vena cava or cutting of the brachial or carotid arteries is only acceptable if the animal has been rendered unconscious by one of the above methods. It should not be used as the sole method of killing an animal. However, it is a particularly effective way of ensuring death following any form of stunning.

Electrocution and Anaesthetic Overdose

Electrocution and anaesthetic overdose are also acceptable methods of euthanasia. However, an anaesthetic overdose can only be administered by your veterinarian. Electrocution is generally not recommended as it requires considerable knowledge and expertise to determine the appropriate voltage and duration for various sized animals. The risk of error is considerable and results in an inhumane situation.

It is essential with any method of euthanasia that death be confirmed. Animals should be monitored for several minutes after the procedure. A short period of muscle contraction (no longer than 20 seconds) prior to a relaxation period consisting of uncoordinated kicking or paddling movements is normal. Death is confirmed in part by the absence of breathing and a heartbeat. The pupils should be fixed and dilated and there should be no blinking response when the cornea is touched. If any signs of life remain, the euthanasia procedure should be repeated. If the animal is alive but unconscious, exsanguination is an effective means of ensuring death.

By their nature, all methods of euthanasia involve risks to human safety. Proper equipment, training and safety precautions are important.

Each farm should develop a protocol and training program for deciding when and how to euthanise animals. Adherence to such a protocol will ensure that animal suffering will be alleviated in a safe and timely manner.