Euthanasia

Government Decree on the Protection of Animals Used for Scientific or Educational Purposes (564/2013),

Annex 2: Methods of killing animals

 

Death must always be confirmed after euthanasia.

 

Euthanasia by cervical dislocation

In cervical dislocation, the first neck vertebra is pulled apart from the skull causing severe damage to the brainstem and the spinal cord, which leads to immediate loss of consciousness and a quick death. Cervical dislocation is used mainly for mice. According to the legislation, it may be used for rodents under 1 kg of body weight, but those over 150 g must be first anethetized.

The mouse is set on a work surface where it gets a good hold with its front legs, e.g. a strong metal net or lid of a cage. You should hold on to the base of the tail by pulling back lightly so that the animal grabs onto the surface with its front feet. For example, tweezers or another similar object should be pressed on top of the neck directly behind the base of the skull so that the mouse is pinned tightly onto the surface and cannot pull its head out. Then, pull sharply and strongly at the base of the tail with the other hand, which causes the neck vertebrae to dislocate. The head must be tightly in place before pulling the tail in order to prevent it from slipping free when pulling the tail. An alternative, somewhat more difficult technique, is pressing the back of the skull with the thumb and index finger of one hand and pulling the tail with the other hand. It is important to act quickly and decisively, but without haste.

 

Euthanasia with carbon dioxide

The mouse or rat is placed in the euthanasia chamber before filling the chamber with carbon dioxide. Putting an animal into a prefilled chamber is forbidden by law. Using the home cage as a euthanasia chamber is recommendable because it minimizes the need for handling the animal and reduces stress. The general recommendation is that carbon dioxide be led into the chamber gradually, approx. 15 - 20 % of the chamber volume per minute. The speed of filling the chamber should be such that the animal will be rendered unconscious as quickly as possible without the high CO2 level inflicting visible irritation or pain on the animal. The animals must be observed during the filling process and precaution should be taken to prevent possible malfunctions. The animal should not be taken out of the chamber before it is almost certainly dead. Some rodents may stop breathing at a certain CO2 level, in which case it is easy to mistake them for being dead. The gas flow should continue at least for one minute after apparent death. After removing the animal from the chamber, it should be observed for a while. Death may also be secured through other means after the gassing, e.g. cervical dislocation or decapitation. Carbon dioxide must not be used for euthanising newborn or very young  rodent pups, under the age of ten days, as they are very tolerant of hypoxia which delays unconsciousness and death considerably.

Last updated: 5.1.2017