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From time to time, every producer is faced with the difficult task of having to destroy pigs that have become ill, injured, or are the weak runts of a litter. Euthanasia is defined as "a humane death occurring without pain or distress". Decisions about how to handle these pigs must be made with a frank and open discussion between employer and employee or between family members, with the advice of a veterinarian. While the most important factor is pig welfare, economics and public health must also be considered.
An ill or injured pig will fall into one of the following categories:
Appropriate individual medical or surgical treatment may be cost effective for some conditions. If the signs of distress are not alleviated within hours of treatment, option four should be applied.
In the case of an injury such as a broken leg, salvage for human consumption may be a viable option. However, such a pig may not be suitable to be transported to an appropriate facility. Authorization from a veterinarian should be obtained in these situations.
Separation to hospital pens with little or no competition may be all that is necessary for some of the unthrifty pigs such as those with residual lung damage from pneumonia or umbilical or inguinal hernias to go on to do much better.
When the above options are not viable, or if the pig is in any kind of distress, the farmer is left with the task of humanely killing the pig.
The following are considered appropriate methods of euthanasia in swine: carbon dioxide chamber, gunshot, captive bolt pistol and severing carotid artery, electrocution, anesthetic overdose, and blunt trauma.
Table 1 indicates how appropriate each method of euthanasia is for the various sizes of pigs.
APPROPRIATE METHODS OF EUTHANASIA DEPENDING ON SIZE*
|PIGLET Up to 12 lbs.||NURSERY PIG Up to 70 lbs.||GROWER PIG Up to 150 lbs.||FINISHER PIG Up to 150 lbs.||MATURE SOW OR BOAR|
|Carbon Dioxide||Yes||Yes||Not Practical|
*Acknowledgement - American Association of Swine Practitioners
Some of the considerations for each method are summarized as follows:
1. Carbon Dioxide:
A plastic garbage-type bucket with a lid could be used. Carbon dioxide is heavier than air so it should enter at the top with the air vented from the bottom to a non-occupied area. Because of the container size needed, it is not practical to do pigs over 70-80 lb. The area must be well ventilated. While carbon monoxide could also be used, it is not recommended because of the high risk to human health.
Proper, safe handling and storage is a must. Some skill is required to achieve correct aim. Rifles (.22 caliber) are often used, however some prefer shotguns to reduce the potential for ricochet of the bullet. Preferably gunshot would be done outside and a person assisting with restraint would always stand behind the shooter. If the pig is large and when the degree of penetration into the brain is questionable, the carotid artery should be severed as quickly as possible after the animal is stunned.
3. Captive Bolt Pistol:
This method is similar to gun shot. The charge size must be appropriate for the size of the pig. While the captive bolt pistol is held firmly against the skull, a gun would be held 2-10 inches away.
The pistol is directed at the midline of the forehead, one inch above the level of the eyes, and directed upwards at approximately 20o towards the brain. Severing the carotid artery is almost always necessary after stunning with a captive bolt pistol on a large animal, because of poor penetration to the brain.
This method should only be performed with a commercially available hog stunner which has built-in safety devices to minimize hazard to humans. It is a time-consuming procedure and the equipment may not be readily available. However, once the equipment is purchased, ongoing cost and maintenance is very low.
5. Anesthetic Overdose:
Concentrated barbiturate drugs are given IV (or intra-peritoneal to piglets) to cause a progressively deeper state of anesthesia until cardiac arrest occurs. Federal drug regulations limit the availability of these drugs and therefore the application of this method may be limited.
6. Blunt Trauma:
A firm, sharp blow to the top of the head is a very efficient way to euthanise piglets less than 2-3 weeks of age. The blow must be done with determination to render the piglet dead instantaneously.
The method of euthanasia must be appropriate for the size of the pig; be safe for the handler; render the pig dead quickly; be economical; and, be easily learned and repeatable by the operator.
Another important factor is that the method should not be objectionable to the person charged with that duty. Preferably, a person with duties other than farrowing and nurturing newborns should take on this responsibility.
Proper planning and dialogue can help to avoid the unpleasantness of a sometimes necessary task.
September 1st, 1998
Dr. Marvin McCallister Extension Veterinarian