WO2007129100A1

WO2007129100A1 - Humane animal euthanasia method

Info

Publication number: WO2007129100A1
Application number: PCT/GB2007/001703
Authority: WO
Inventors: Colin Peter Smith
Original assignee: Rentokil Initial 1927 Plc
Priority date: 2006-05-09
Filing date: 2007-05-09
Publication date: 2007-11-15
Also published as: GB0609164D0

Abstract

The present invention is directed to an apparatus and method for killing animals in a humane manner. The method comprises generating a foam by mixing a liquid containing a foaming agent and a gas and delivering that foam into a container containing animals to be killed. The gas is received from a selected one of a plurality of balloons adapted to retain the said gas.

Description

Humane Animal Euthanasia Method

The present invention is directed to a humane animal euthanasia method. In particular, the present invention is directed to a humane method suitable for killing animals, such as poultry, in large numbers, for example, for disease control purposes .

In the event of a disease outbreak, for example avian influenza, in an animal population, it may be necessary to kill large numbers of animals in order to contain the disease. This typically involves the slaughter of an entire herd or flock of animals .

Killing animals in large numbers presents a number of problems. In particular, it is difficult to provide an effective, reliable method of killing large numbers of animals that is also humane.

The chosen animal euthanasia method must be effective to control the problem, such as a disease, that is being addressed. This typically requires the animals to be killed in a relatively short period of time, often with little prior notice.

The method must limit the risk to the humans involved with implementing the method. Some methods of killing animals are themselves potentially dangerous to humans. Another potential problem is exposure to the problem, such as a disease, that the process is intended to control. The use of a gas that is effective to kill the animals solves at least some of the problems identified above and a number of methods for using gases to kill animals are known in the art . Examples of gases that are known to be effective for killing animals include: carbon dioxide; a mixture of carbon dioxide and air; a mixture of carbon dioxide and nitrogen or some other inert gas; nitrogen; a mixture of nitrogen and one or more other inert gases; and carbon monoxide .

Many methods for killing animals using gases require animals to be introduced into a separate container that contains the gas that is to kill them. This is effective if animals are to be killed individually or in very small numbers, but presents a number of practical problems in the event of animals being killed in large numbers. For example, the method requires animals to be collected and placed in the separate container. This collection may present logistical difficulties, particularly if a large number of animals are to be killed, presents a potential health risk to the humans moving the animals to the container and may be distressing to the animals being killed.

There are a number of other problems with using gases to kill animals in large numbers.

In order for a method of killing animals to be humane, the method must be effective, in the sense that all of the animals are killed, and must be quick and not distressing to the animal. Many prior art methods of killing animals using gases are not able to meet these demands. The container in which the animals are killed should be effectively sealed to reduce the loss of gas from the container and to ensure that the level of the gas in the container is kept relatively constant. The quickest and easiest way of killing an entire flock of poultry, for example, is to introduce the gas into the poultry house. Most poultry houses do not provide an effective seal for the gas and so most poultry houses are not suitable for use with this method, without some prior modification, which may be expensive, both in terms of both time and money, may be impractical, and may not be possible within the timescales given to kill the animals .

The concentration of some gases required to kill is often relatively high. For example, for carbon dioxide, a concentration in excess of 50% may typically be required and for nitrogen, a concentration of more that 95% may be required. It is often difficult to obtain such concentrations, particularly if animals are to be killed in large numbers. This is particularly problematic if animals are to be killed in locations, such as poultry houses, which do not provide an effective seal to prevent gas from escaping or in locations that make it difficult to fill an entire volume with the required concentration of gas (for example, poultry sheds with very high ceilings) .

The use of many inert gases, such as xenon, krypton and argon, can be harmful to humans, especially with long exposure, which may occur if very large quantities of animals are being killed. The use of carbon monoxide can be highly effective, but it is highly toxic to humans .

Carbon dioxide is known to be very effective for killing animals. Carbon dioxide also has an anaesthetic effect. However, there are a number of practical problems with the use of carbon dioxide, especially in relation to the killing of animals in large numbers. Carbon dioxide gas is typically delivered using a liquid source, which may have a temperature as low as -78 degrees centigrade. This liquid must be vaporized prior to use. It can be difficult and expensive to carry out the vaporization process quickly enough to produce the quantities of carbon dioxide required to kill large numbers of animals . Similar problems are encountered with the storage and delivery of other gases that could be used for animal euthanasia.

The present invention seeks to address at least some of the problems outlined above.

The present invention provides a method of killing animals, the method comprising the steps of: receiving a liquid (such as water) containing a foaming agent; receiving a gas,- generating a foam (for example, a high expansion foam) by mixing said liquid and said gas; and delivering said foam into a container containing animals to be killed, wherein said gas is received from a selected one of a plurality of balloons adapted to retain the said gas. The gas used is selected so that it is effective to kill the said animals . The method provides a method of animal euthanasia, whereby the level of pain and distress caused to the animals being killed is minimised. The present invention also provides an apparatus, for example an animal euthanasia apparatus, comprising: a first inlet for receiving a liquid (such as water) containing a foaming agent; a second inlet for receiving a gas; a fan for generating a foam (such as a high expansion foam) from said liquid and said gas; a first outlet for outputting said foam, for example, into a substantially enclosed space containing one or more animals; a plurality of balloons adapted to retain the said gas,- and a valve for selectively connecting said balloons to said second inlet of said chamber. The gas used is selected so that it is effective to kill the said animals.

The use of foam containing a gas selected to kill animals has a number of advantages over the use of gas alone . Foam can be used in many situations where gas would not be appropriate; for example, in enclosures, such as a poultry sheds, that would allow the gas to leak. The present invention provides a large amount of foam relatively quickly that can be used to kill the animals quickly, typically in a few seconds. This arrangement provides a quick, effective and humane method of killing animals in large numbers .

A further advantage to the use of foam is the wetting function of the foam. If the invention is used in a dusty environment (such as a poultry shed) , the foam acts to wet the dust which facilitates the subsequent cleaning of the environment. This is particular advantageous in circumstances where the dust may itself be dangerous, for example by containing disease-carrying animal droppings . In use, the foam generator may be placed at an open doorway of a poultry shed, or another location where animals are retained in a substantially enclosed space. The foam generator may be operated remotely, such that human operators need not be exposed to the animals to be killed. This has a number of practical advantages and also reduces the potential health risk to the operators of the equipment .

The provision of a plurality of balloons to store the gas and to supply the gas to the foam generator has a number of advantages. In particular, by using a plurality of balloons, the gas can be generated from a liquid store more slowly than the gas is required to be delivered to the foam generator.

The said gas may be carbon dioxide. Alternatives to carbon dioxide include, but are not limited to, a mixture of carbon dioxide and air, a mixture of carbon dioxide and nitrogen or some other inert gas, nitrogen, a mixture of nitrogen and one or more other inert gases, carbon monoxide and other toxic gases, such as sulphuryl fluoride.

The liquid supplied to said foam generator may include a disinfectant such that the foam generated has a disinfecting property.

In one embodiment of the invention, the fan has a diameter of the order of 1 metre. In other embodiments of the invention, the fan diameter may range between about 20 and 150 centimetres. In one embodiment of the invention, the balloons have a capacity of around 100 cubic metres. In other embodiments of the invention, the balloons may have a capacity of up to 10,000 cubic metres. The balloons may also be used as a means for mixing two or more gases to ensure even distribution of the gases .

In one form of the invention, each of the said balloons is filled with the said gas on a continuous basis. In an alternative arrangement, each of the said balloons is filled with the said gas with the exception of the balloon that is connected to the second inlet.

The gas may be stored in liquid form, with the gas being generated using a vaporizer. In a preferred form of the invention, each of said balloons is connected to a different one of a plurality of vaporizers . This enables gas to be supplied to each balloon more slowly than gas is required to be delivered to the foam generator.

A single container may be provided that contains the liquid used by the said vaporizers for generating the said gas. Alternatively, a plurality of such containers may be provided; for example, each of said vaporizers may be connected to one of said containers, wherein, in use, each vaporizer is arranged to generate the said gas from liquid stored in the container to which it is connected.

In one form of the invention, the balloon to which the second inlet is connected is selected on the basis of the quantity of gas contained within the said balloons . In one form of the invention, the second inlet is connected to each of said balloons in turn and remains connected to a particular balloon until the quantity of gas contained within that balloon falls below a predetermined threshold.

The said gas may be a mixture of two or more gases . In such an arrangement, one or more of the said two or more gases may be stored in liquid form, with one or more vaporizers being provided to generate the required gases. Each of said balloons may be used to store the mixture of the two or more gases .

The present invention will now be described, by way of example only, with reference to the accompanying schematic drawings in which:

Figure 1 shows a plan view of an arrangement in accordance with an embodiment of the invention;

Figure 2 shows a section, viewed from above, of a foam generator suitable for use in the arrangement of Figure 1; and

Figure 3 is a schematic diagram of an exemplary gas container 8 suitable for use with the foam generator of Figure 2.

Figure 1 shows a poultry shed 2, a foam generator 4, a water/foaming agent container 6 and a gas container 8. The foam generator 4 is placed at a doorway 3 of the shed 2 and is used to generate a foam that is used to fill the shed 2. The bubbles of the foam are generated from liquid stored in the water/ foaming agent container 6 and gas stored in the gas container 8. Figure 2 shows an exemplary foam generator 4. The foam generator 4 comprises a chamber 10 having a first inlet 12 for receiving liquid from the water/foaming agent container 6, a second inlet 14 for receiving gas from the gas container 8, a first outlet 16 for outputting foam into the poultry shed 2, and a fan 18.

As is well known in the art, foam can be generated by mixing a suitable foaming agent with water in the correct concentrations and forcing large volumes of a gas (typically air) into the water/foam concentrate mixture using a fan. This method is well established and used in many applications, including as a fire extinguisher. By way of example, the foaming agent may be a derivative of sodium lauryl sulphate. In one embodiment, 25 to 200 litres of foaming agent may be provided, mixed with 1 part foaming agent to 500 parts water.

Foams are typically classified on the basis of the amount of expansion that occurs when the water/foaming agent solution is aerated. Generally, expansion rates up to 20 are termed "low expansion", expansion rates of between 20 and 200 are termed "medium expansion" and expansion rates of 200 or above are termed "high expansion" . Low expansion foams have a high water content, therefore producing relatively wet, heavy foam. High expansion foams have a low water content, therefore producing relatively dry and light foams.

In the present invention, the use of high expansion foam is preferred. High expansion foams are able to fill the poultry shed 2 relatively quickly. Further, the foam has a high gas content, and it is the gas that is used to kill the animals within the shed 2. Yet another advantage is the lower use of water. Reducing the water consumption means that the amount of water required to be delivered to the site is reduced and also simplifies the clear-up operation after the animals have been killed. Further, high expansion foams can typically be delivered for longer periods of time than low or medium expansion foams . For example, foam durations of around 20 minutes are readily achievable using high expansion foams.

Figure 3 is a schematic diagram of an exemplary gas container 8 suitable for providing the foam generator 4 with large quantities of a gas, such as carbon dioxide.

Carbon dioxide is typically stored, under pressure, in liquid form as this enables carbon dioxide to be stored and transported in an economical manner. The container 8 of Figure 3 comprises first 20, second 22, and third 24 liquid carbon dioxide stores. The first, second and third liquid carbon dioxide stores 20, 22 and 24 are connected to first, second and third vaporizers 26, 28 and 30 respectively. The vaporizers convert the liquid carbon dioxide into a carbon dioxide gas in a manner well known in the art . The carbon dioxide gas generated by the first, second and third vaporizers 26, 28 and 30 is used to fill first, second and third balloons 32, 34 and 36 respectively.

The first, second and third balloons 32, 34 and 36 are connected to a valve 38 by pipes 40, 42 and 44 respectively. The valve 38 connects one of the pipes 40, 42 and 44 to an outlet 46. The outlet 46 provides carbon dioxide gas to the second inlet 14 of the foam generator 4.

The foam generator 4 requires a large volume of carbon dioxide gas to be provided at the inlet 14 in a short period of time. However, it is relatively difficult and expensive to vaporize liquid carbon dioxide sufficiently quickly to meet this need. By providing a plurality of balloons 32, 34 and 36, each of which provides carbon dioxide gas for a fraction of the time, the rate at which each balloon need be filled by the vaporized carbon dioxide is significantly reduced.

Although carbon dioxide is used in the exemplary embodiment of the invention described above, this is not essential. Other gases, such as nitrogen, argon, or carbon monoxide could be used. Furthermore, the skilled person would be aware of other gases, and combinations of gases, that would be suitable for use with the present invention.

In embodiments of the invention in which combinations of gases are used, the balloons may be used as a means for mixing the gases to ensure an even distribution of the gases .

In the exemplary embodiment described above, three gas storage balloon are used. Of course, more or fewer balloons could be used in any particular embodiment of the invention. Similarly each of the vaporizers 26, 28 and 30 may be connected to a single liquid carbon dioxide store, rather than the separate carbon dioxide stores shown in Figure 3. A disinfectant could be added at the foam generation stage, for example by adding a suitable disinfectant to the water/foaming agent mixture, or by adding providing an additional input to the foam generator providing a supply of disinfectant. The inclusion of a disinfectant in the'-⁷ foam that is used would have the advantage of at least partially disinfecting the area to which the foam is applied. The use of a disinfectant would make the task of cleaning up the treated area safer.

As discussed above, the present invention is applicable to the killing of poultry in large numbers. However, the invention is not limited to such a use. For example, the present invention can be used for killing moles, rabbits in burrows and rats in sewers . The present invention is also applicable to the culling of larger animals, such as pigs.

Claims

CLAIMS :

1. A method of killing animals, the method comprising the steps of: receiving a liquid containing a foaming agent; receiving a gas; generating a foam by mixing said liquid and said gas; and delivering said foam into a container containing animals to be killed, wherein said gas is received from a selected one of a plurality of balloons adapted to retain the said gas.

2. A method as claimed in claim 1, further comprising the step of filling each of said balloons with the said gas.

3. A method as claimed in claim 1, further comprising the step of filling each of the said balloons that is not connected to the second inlet with the said gas .

4. A method as claimed in any preceding claim, further comprising the step of generating said gas from a liquid stored in a liquid store.

5. A method as claimed in claim 4, wherein the step of generating said gas comprises the use of a vaporizer.

6. A method as claimed in any preceding claim, further comprising the step of selecting the balloon to which the second inlet is connected on the basis of the quantity of gas contained with the said balloons.

7. A method as claimed in any one of claims 1 to 5, further comprising the step of connecting the second inlet to each of said balloons in turn and retaining the connections until the quantity of gas contained within the balloon to which the second inlet is connected falls below a predetermined level.

8. A method as claimed in any preceding claim, further comprising the step of receiving a disinfectant, wherein said step of generating said foam comprises mixing said liquid, said gas and said disinfectant.

9. A method as claimed in any preceding claim, wherein said gas is carbon dioxide.

10. An apparatus comprising: a first inlet for receiving a liquid containing a foaming agent; a second inlet for receiving a gas; a fan for generating a foam from said liquid and said gas; a first outlet for outputting said foam; a plurality of balloons adapted to retain the said gas ; and a valve for selectively connecting said balloons to said second inlet of said chamber.

11. An apparatus as claimed in claim 10, further comprising a plurality of vaporizers arranged to generate said gas from a liquid stored in a liquid store, wherein each of said balloons is connected to, and receives gas from, one of said vaporizers .

12. An apparatus as claimed in claim 10 or claim 11, wherein, in use, each of said balloons is filled with gas on a continuous basis.

13. An apparatus as claimed in claim 10 or claim 11, wherein, in use, each balloon other than the balloon to which the second inlet is connected by said valve is filled with gas.

14. An apparatus as claimed in any one of claims 10 to 13, wherein said valve is arranged to connect said second inlet to a selected one of said balloons in dependence on the quantity of gas contained within the said balloons .

15. An apparatus as claimed in any one of claims 10 to 13, wherein said valve is arranged to connect said second inlet to each of said balloons in turn, wherein, in use, the connections are maintained until the quantity of gas contained within the balloon to which the second inlet is connected falls below a predetermined level.

16. An apparatus as claimed in any one of claims 10 to 15, wherein said foam is a high expansion foam.

17. An apparatus as claimed in any one of claims 10 to 16, wherein said gas is carbon dioxide.

18. An apparatus as claimed in any one of claims 10 to 17, wherein said liquid contains a disinfectant.