the various exemplary embodiments of the present invention include a method of using an apparatus for humanely and substantially painlessly euthanizing one or more animals . the method is preferably utilized in a laboratory or veterinarian &# 39 ; s setting with personnel trained at euthanizing animals . these embodiments will become more apparent in the follow description and related fig1 and 2 . the various exemplary embodiments of the present invention include a method of euthanizing one or more animals . the method is comprised of the steps of placing the one or more animals into a holding cage , introducing a gas into the holding cage at a first flow rate until a narcotic set point for the one or more animals is achieved , ceasing introduction of the gas into the holding cage for a first wait period to ensure narcotic effects of the gas overtake the one or more animals , introducing the gas into the holding cage at a second flow rate until the gas accounts for approximately 100 % of an internal atmosphere inside the holding cage , ceasing introduction of the gas into the holding cage for a second wait period to ensure irreversible euthanasia of the one or more animals , and removing and disposing of carcasses of the one or more animal the exemplary embodiments of the present invention can be connected to cages of various sizes and constructions . in an exemplary embodiment described more in depth below , the cage in which the one or more animals is euthanized is comprised of plastic , however , the cage 60 can also be of wire or mesh construction and then covered or sealed to ensure that the co 2 introduced to the cage remains substantially in the cage . no matter the composition of the cage material , a typical cage comprises a floor and four upstanding walls to form a generally rectangular surrounding . the cage may also comprise a top lid or cover 65 for enclosing the cage . the present invention is designed to enable the laboratory personnel to efficiently and effectively attend to the destruction of the laboratory animals at the conclusion of the tests or experimental procedures . the method and apparatus of the present invention enables the animals to be destroyed painlessly and humanely without removing the animals from the cages in which the procedures were last performed . thus , the animals need not be handled by the laboratory technicians . to this end , the apparatus of the present invention incorporates covers which fit on the cages , and a means to supply a gaseous medium to the cages in an efficient and effective manner . in particular embodiment , the apparatus incorporates a control means 50 which enables the introduction of the proper quantity of gaseous medium into the cages without need for highly skilled supervision of this procedure . in the present invention , the covers 65 can be fit to various sizes of cages . the cover may include an inlet 62 through which one may introduce the gaseous medium . the cover may also comprise one or more exhaust outlets 64 . however , each of the inlet and the one or more exhaust outlets can be located on the upstanding walls of the holding cage . the various exemplary embodiments include at least one co 2 gas source 10 such as , for example , one or more research or medical grade co 2 pressurized containers 10 . it is preferred that the co 2 gas source have a pressure range of approximately 20 pounds per square inch ( psi ) to approximately 150 psi . the co 2 gas pressurized containers 10 are preferably connected to a regulator 12 . in a preferred embodiment , the regulator regulates the co 2 internal pressure at approximately 15 psi . connected to the regulator 12 is a manifold 20 further connected to at least a first solenoid 30 and a second solenoid 40 . the first solenoid 30 is then connected to a first flow meter 35 and the second solenoid 40 is connected to a second flow meter 45 . although fig1 is a graphic representation of an exemplary embodiment comprising a first flow meter and a second flow meter , it should be noted that a single flow meter may function in the role of both the represented first flow meter and second flow meter . in the embodiments comprising only a first flow meter , the first flow meter may be set to a first flow rate during a first predetermined flow period of time and to a second flow rate during a second predetermined flow period . setting the first flow meter to more than one flow rate at different times can be performed manually or automatically via a controlling means , such as , for example , a computer . each flow meter is then connected to a respective bulkhead outlet which then can be inserted into the inlet 62 in the cover 65 . in a preferred embodiment , the first flow meter and the second flow meter are connected to a single bulkhead outlet 61 and then fed into the inlet , here present in the cover . in the various exemplary embodiments , the first flow meter and the second flow meter may be set to different flow rates . further , the first flow meter and the second flow meter may be turned on and off independently from the other . the first flow meter and the second flow meter may be connected to a control means . the control means may be programmed to turn on the first flow meter and the second flow meter at one or more particular predetermined times , for a predetermined amount of time and at a predetermined flow rate of gas . when the at least one of the first flow meter or the second flow meter of the present apparatus is turned on , co 2 gas enters a cage via the inlet . the co 2 , being a gas heavier than oxygen ( o 2 ) and nitrogen ( n 2 ), the other two main chemicals in safe and breathable air , settles to the bottom part of the cage , that is , closer to the floor . as the co 2 fills the bottom part of the cage , the safe and breathable air is displaced up and out the one or more exhaust outlets . normally , co 2 is not a dangerous gas and typically comprises approximately 0 . 1 % of breathable air . however , in high concentrations , the co 2 can anaesthetize a mammal and eventually asphyxiate it . in the various exemplary embodiments of the present invention shown in fig2 , one or more animals are placed in a cage connected to the present apparatus , see step 100 , and the first flow meter is first turned on for a predetermined period of time at a first flow rate to cause narcosis to the one or more animals . see step 200 . after the first flow meter is turned on for a predetermined first flow period of time , the flow meter is turned off and a predetermined first wait period occurs to better ensure that the narcosis , a narcotic set point , of the one or more animals sets in . see step 300 . next , the second flow meter is turned on for a predetermined second flow period of time at a second flow rate until the co 2 level in the cage is substantially about 100 %. see step 400 . finally , after the second flow meter is turned off , a second wait period occurs to ensure that nonreversible euthanasia of the one or more animals occurs . see step 500 . once the one or more animals have been nonreversibly euthanized , the one or more animals &# 39 ; carcasses can be properly disposed of . see step 600 . by gradually overcoming the animals with co 2 to the narcotic set point first , the animals do not thrash about and experience stresses often involved and observed when the animals are introduced to a much higher concentration of co 2 all at once . thus , the animals humanely and unknowingly are overcome by the co 2 , and then co 2 concentration is greatly increased to ensure that the animals are not revived . in an exemplary embodiment wherein the one or more animals are small rodents , such as for example , rats or mice , the small rodents are placed in the cage . the cage is covered with the cover 65 and the apparatus is connected to the cage via the inlet . the first flow meter is turned on at approximately 2 liters per minute ( lpm ) for approximately 30 to approximately 35 seconds to achieve an approximately 20 % co 2 level in the cage . a first wait period of approximately 15 to approximately 20 seconds ensures that the small rodents are substantially overcome by co 2 - induced narcosis . the second flow meter is then turned on at approximately 8 lpm for approximately 60 seconds to ensure approximately 100 % co 2 in the cage . then a second wait period of approximately 2 minutes in the 100 % co 2 atmosphere ensures irreversible euthanasia of the small rodents , the carcasses of which can then be disposed of . of course , the actual flow rates and times for introducing the co 2 and wait periods can vary depending upon the size of the cage and the size , number and type of animal involved . while this invention has been described in conjunction with the specific embodiments outlined above , it is evident that many alternatives , modifications and variations will be apparent to those skilled in the art . accordingly , the preferred embodiments of the invention as set forth above are intended to be illustrative , not limiting . various changes may be made without departing from the spirit and scope of the invention .
the present invention is a method for euthanizing animals humanely and painlessly by introducing a gas at a first flow rate to cause the animals to reach narcosis . then , the gas is introduced at an elevated second flow rate to induce a death to the animal that substantially meets or exceeds national and international standards for euthanasia .