From the Editor

Care of individual pigs is a measure of farm welfare

Swine health veterinarians are population specialists. We look at the way the whole herd functions and set goals for the group, not for the individual pig. However, care and attention given to the individual pig distinguishes a herd with good welfare from one with poor welfare. Veterinarians and producers must pick out the one pig in the group that needs to be treated differently from the rest. Typically, sick pigs that are identified, moved to a sick pen, and treated individually will recover quickly. When sufficient numbers of pigs from the sick pen have recovered, they can be moved as a group back into the regular stream.

Some pigs do not respond to treatment. Timely euthanasia of injured pigs, sick pigs that are suffering, and sick pigs that do not respond to treatment is a critical component of good welfare on a farm. Veterinarians are fortunate in that they can use drugs specifically designed for rapid and humane euthanasia. Producers do not have the same options. One important part of a herd health program is to develop a euthanasia action plan for the farm.¹

Options for on-farm euthanasia conducted by farm workers must take into consideration human safety, welfare of the pig, suitability for the size of the pig, and practicality.¹ Gunshot and penetrating bolt are recommended for pigs bigger than 5.5 kg. Skill, training, and adherence to firearms regulations are necessary for these methods. Although blunt trauma is recommended as a rapid and humane method for nursing pigs, many people find this method emotionally unacceptable. An alternative for nursing and small nursery pigs that are unconscious or semiconscious is an intra-cardiac injection of a hypertonic solution of magnesium sulfate (MgSO₄). Epsom salts, which is sold in pharmacies, is a readily available form of magnesium sulfate. To make a hypertonic solution, mix equal parts of Epsom salts and boiling water. For example, mix one cup of Epsom salts into one cup of boiling water. Stir well. There may be some crystals left in the bottom of the cup. When the solution has cooled, it may be used for intracardiac injection at a dose of 3 mL per kilogram of body weight. A 4-kg pig requires 12 mL. Veterinarians may train farm personnel to administer an intracardiac injection in unconscious pigs. A pig that is semiconscious may be sedated with azaperone prior to the intracardiac injection.

Carbon dioxide (CO₂) is also considered an acceptable method for euthanizing small pigs.¹ Producers must build an appropriate box in which to confine pigs for administration of CO_2. Research by Dr Anne Deckert indicates that pigs euthanised by CO₂ demonstrate marked escape behavior.² Producers using this method should be warned about this behavior. In Dr Deckert's study, argon (Ar) was used as an alternative to CO₂. Although the Ar did not induce escape behavior, the time to unconsciousness was longer (1.5 to 3 minutes)with Ar than with CO₂ (22 to 27 seconds). In this study, two pigs regained respiration and pulse 1 hour after removal from the gas. Therefore, these researchers recommend an intracardiac injection of MgS0₄ once the pig is rendered unconscious due to the gas. Three pigs in their trial, all with pericardial infections, required 30 mL of MgS0₄ solution for complete cardiac arrest. They recommend the routine use of 30 mL of hypertonic MgS0₄ solution as the dose for unconscious pigs with a body weight of 1 to 20 kg.

References

*1. On-farm euthanasia of swine - Options for the producer. Available at www.porkboard.org. Accessed November 18, 2003.

*2. Gunn H, Deckert AE, Friendship RM, Dewey CE. Development and evaluation of an alternative euthanasia technique in swine. Proc AASV. 2002:39-41.

*Non-refereed reference.

-- Cate Dewey