Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
108457~
This invention relates to a method of and means
for handling animals, and in particular to the handling
of ar.imals such as sheep, cattle and other animals for
handling or vetPrinary purposes.
5. In animal husbandry there is often the requirement
to restrain or immobilize an animal for veterinary
purposes, or in the case of a sheep, to allow shearing
to take place. Conventionally this has been by some
mechanical means for holding and restraining the animal,
10. or in the shearing of sheep to manually restrain the
animal by the shearer while the shearer himself carries
out the shearing operation. With animals such as wild
beasts, the animal is drugge~ and anaesthetised, but this
~ is a relatively slow process, for it takes time for the
; 15. drug to anaesthetise the animal, and also after the treatment
the animal takes a degree of time in order to recover.
The present invention relates to an improved method
and means of immobilizing and handling animals, and is
concerned with an electrical method and apparatus for
20. carrying out this manner of handling animals.
BACKGROUND OF THE INVENTION
In the field of electro-treatment of animals and
humans, there is disclosed in the United States Patent
No. 535,905 dated March l9, 1895; "A Method of and Apparatus
25. for Obtaining Nerves", granted to Horton W.P. and Jones A.B.
Also U.S. Patent No. 2,866,461, granted December 31st, 1958
to R. Suzuki, for "Apparatus for Producing Electric
Anaesthesia" relates to apparatus for the electro-anaesthesia
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2.
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where the patient is anaesthetised in the area of the
operation to be performed. Also U.S Patent No.
3,083,463, dated 2nd April, 1963, to Brooks B. and
Sylvane A.A., relates to "Dental Drilling and Apparatus
5. Therefore".
Also it is known that electro-anaesthesia on large
animals can be carried out, such as discussed in the
article by C.E. Short, D.V.M. in Journal of American
Veterinary Medical Association, Volume 145, No. 11,
10. entitled "The ApplicaLion of Electro-Anaesthesia on Large
Animals". This discusses the techniques of total
anaesthesia by passing an electric current through or
around the head of the animal and results in total
relaxation of the animal.
15. SUMMARY OF THF INVENTION
By research it has been discovered that animals
can be immobilized by using an electrical current flow
of low voltage and small currents, and of a particular
frequency to Eorm a pulse, with a relatively short pulse
20. width, with a relatively large duration between the pulses,
thus causing the muscles to be in a rigid state, or state
of tetany.
This has a definite advantage in ~he shearing of
sheep, where the sheep can be rigidly immobilized in a
25. desired position of the limbs, this a~lowing a purely
mechanical shearing of the sheep to take place~
Also with other animals, such as cattle, horses
and even wild animals, the animals can be immobilized
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while in a standing position, to allow veterinary and animal
husbandry work to be carried out.
According to one aspect of the present invention,
there is provided a method of producing temporary immobiliza-
tion of an animal undergoing animal husbandry without rendering
the animal unconscious, including the step of after first
- implanting electrodes subcutaneously and then clipping them to
the hindquarters and forwardly thereof along the spine of the
animal, the electrodes piercing the skin and the fatty tissue ;~;
beneath thereby to contact the ionized fluids beneath the skin
allowing a low voltage to be used, subjecting the electrodes
to a current flow of a potential of about 40 volts maximum to
produce immobilizing simultaneous muscular tetanic contraction
in the animal.
According to a further aspect of the present
invention, there is provided apparatus for immobilizing
j animals, the apparatus being characterised by an electric
! power source, electrodes connected to the power source, said
electrodes beiny characterised by (1) needles with sharp ends
to be implanted subcutaneously in the animal in combination
with (2) spring--biased clips for clamping to the hide of the
animal to retain the needles.
BRIEF DESCRIPTION OF THE DRAWINGS
. FIG. 1 is a diagrammatic illustration of the
immobilizer,
FIG. 2 is a circuit diagram of the immobilizer, and
FIG. 3 is a chart of the currents required for
various weights of cattle.
DESCRIPTION OF THE PREFERRED EMBODIMENT
It has been determined that the immobilization of
animals can be carried out by an electric current, having a
potential of 40 v. and a current in the vicinity of 50 milli-
amperes will immobilize a sheep, and that about 100 milliam-
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peres is required for immobilizing cattle, the current being
pulses of 50 Hertz, each pulse being of 1 millisecond and
spaced 20 milliseconds apart.
Research work to date has shown that a current
having a constant amplitude driven by a low voltage high
impedance source is safer for operators to use, and this can
be achieved if the electrodes which are attached to the animal
are so designed that they pierce the skin at the point of
application, so as to make contact with the ionized fluids
under the skin and/or in the muscular tissue of the animal.
Indeed the work has shown that it is the magnitude
of the current for a particular wave characteristic, frequency
and points of application that determines the immobilizing
effect, rather than the voltage required to
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drive this current.
The skin of most animals is comprised of horny
(dry cell) outer layers beneath which is found a layer
of fatty tissue, and under this fatty tissue layer exist
the ionized body fluids and muscular tissue.
The electrical resistivity of the horny outer layers
in the adjacent fatty tissues is high, relative to the
electrical resistivity of the ionized body fluids and
muscular tissue.
If electrodes were simply placed or clipped on the
outer skin, most of the voltage would be consumed in
driving the required current through the horny outer
layers and adjacent fatty tissues, while only a small
part of this voltage would be consumed in driving the
required current through the ionized body fluids and
muscular tissue within the animal.
On the other hand, if the electrodes pierce the skin
first and make contact with the ionized body fluids and
muscular tissue, relatively low voltages, safe for the
human operators to handle, would be required to drive
the immobilizing currents through the animals.
It was also found that the resistance between the
electrodes to some extent, depended upon the area of
contact that the electrodes made with the ionized body
fluids and muscular tissue, so that as this area
increased the resistance between the electrodes decreased.
In particular application on cattle and sheep
using a pulsed current source of 50 Hertz frequency,
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and a pulse width of 1 millisecond whose amplitudes
could be controlled accurately between 0 and 1 amp.
and whose voltage did not exceed 40 volts, the largest
animals were easily immobilized without detrimental
effect to the animals or electrical hazard to the human
operators on application of the electrodes.
In a particular design of the electrodes, a
spring-actuated plunger incorporated in an insulating
housing and operated by a trigger mechanism which can
be reset, contains on one end of the plunger either
barbed, straight or current needles, depending on the
requirement, connected to a conducting strip or rod
which makes contact with the current source on operation
of the plunger. The barbed or curved needles ensure
that the electrodes remain attached to the animals even
though they may make a violent movement on insertion of
the electrodes.
It is not intended that the electrodes be limited
to the above design, but they may have various shapes or
sizes and be applied in any manner provided that they
preferably contact the ionized body fluids and/or
muscular tissue under the skin of the animals.
The invention is designed to immobilize cattle and
other animals in a quick, safe manner so that operations
such as shearing, dehorning, castration, etc., and other
forms of surgery may be carried out in the field or
elsewhere in an efficient manner, with the minimum of
physical effort required to restrain the animal. The
~ 108457B
animal is immobilized by the passage of the small
electric current through the nerve and the muscle tissue
thus causing tetany, that is the contraction of the
muscles, thus immobilizing the animal and effecting its
nervous system in such a way that the animal is not
conscious of any pain when the correct current is applied.
No ill effects have been observed to date on the
many experiments carried out on animals, but care must be
taken to ensure that the current applied is not so great
that it prevents the animal breathing for a period long
enough to produce asphyxia. It is felt that the
immobilization can have a therapeutic value on the animals.
The electronic unit is equipped with a warning
device which makes a buzzing sound when the electrodes
are not connected, or when the electrodes are making a
poor connection on the animal. This is considered
necessary as the animal will recover from its immobilized
state within a few seconds of removing the required
immobilizing current.
Turning now to FIG. 1, this shows the electronic
unit 1 having an outward lead 2 connected by a plug 3
to a pair of electrode leads 4. Each lead 4 is connected
in this example, to two electrodes, a dart electrode 5
and a clip electrode 6. For large animals such as cattle,
the dart 5 is used first to immobilize the animal, and
then the clip electrode 5 can be inserted in the desired
location.
For the immobilization of sheep, it is not required
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to use the dart electrodes, but the clip electrodes can
be applied directly to the sheep.
FIG. 2 shows a schematic circuit of the immobilizer,
where the output current Io is equal to Ein divided by
the reference resistance (R reference). The error
amplifier and the series transistor T maintain the outward
current Io at a level such that the voltage drop across the
reference resistance (R reference) is equal to Ein. The
voltage from the reference voltage supply is passed to an
adjustable potentiometer P, which provides adjustment
of E in such a way that Io can be adjusted from O up to
; 0.3 amperes. To pulse the outward current the series
transistor T is turned on and off by an oscillator and
transistor switch.
The oscillator is adjusted to such that the output
pulse width is 1 millisecond and the pulses occur at
50 Hertz, and the output current is continuously adjustable
with a resolution of better than 1 milliamp. The voltage
compliance of the output is 40 volts, and this can be
readily changed.
FIG. 3 shows a chart of tests which have been carried
out on cattle, plotting animal weight against peak
current applied to the animals. Experiments have shown
that while it is initially assumed that a variation in
current required would correlate to the animal weight,
that this is not so, for it is shown in the graph that
the general level of immobilization is between 80 and 300
milVamperes. Smaller animals often require greater
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current flow than larger animals, but generally it has
been noticed that younger animals require an increased
current flow for immobilization.
While no direct correlation is yet available, it
may well be that there is a correlation between the
vitality or energy of the animal and current flow.
It has been found that with certain breeds of
cattle, for example BOS TAURUS which is essentially an
English breed, that current values as shown in FIG. 3
are obtained. However with other breeds such as the
tropical breed BOS INDICUS, that higher currents up to
300 milliamperes are required to immobilize the animals.
For the immobilization of cattle, the initial
setting, it is estimated, should be 100 milliamperes,
and the cllrrent then increased or decreased accordino
to the state of immobility induced in the particular
animal. The initial effect is for the animal to stiffen
up to such an extent that breathing is temporarily
arrested. Between 1 arld 2 minutes however, the animal
commences to breath again, which is indicated by the
heaving of the chest wall and flanks.
If signs of breathing are not evi~3ent after this
time, the current setting should be reduced quickly to
allow the animal to breathe, but not so far as to
entirely reduce the stiff condition of the animal.
Animals have been kept immobilized up to twenty
minutes in experiments performed so far, without any
apparent ill effects. It will be noticed however, that
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after several minutes an animal tends to accommodate
itself to the current levels being used, and a further
one or two fine increments of the current may be necessary
to maintain the immobile state.
Where dehorning, castration or some other operation
: is to be performed on the animal, it is preferable to
Y apply a heavier current than the threshold level for
immobility, and to perform the operation without waste of
time, rather than applying a current just over the
threshold level and having to increase the current to
maintain their immobility.
The animals recover immediately, and sheep have
begun grazing within minutes of being removed from the
immobilizing current, and all animals show no signs of
distress after the immobilization.
While the invention is particularly adapted for
completely immobilizing an animal by applying the current
from head to tail of the animal, the animal may be
positioned as desired, and by slightly reducing the
current, repositioning the animal in the desired position,
and then raising the current to cause the animal to
again stiffen. The animal can be held in any position.
Also various portions can be held as desired so that
by applying the current to portions of the body such as a
leg, the leg muscles can then be held in any desired
position. For example, by applying the current to a rear
leg of a horse, that leg is immediately held up by the
passage of the current through the muscles, the leg being
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held in a position whereby shoeing or other treatment
can be carried out on that leg or hoof. Thus by applying
the electrodes to the desired muscles, the leg can be held
as positioned.
Thus it has been found that various parts of the
animal may be in a state of tetany while other parts may
be relaxed. Thus it is possible to stiffen the major
muscles, while the organs are relaxed, for example, the
internal organs, testes and mammary glands.
Cows while being immobilized have been milked
substantiating the fact that various organs can be
relaxed.
It has also been found on investigation, that
while the optimum current to be applied is a pulse
of a short time interval such as 1 millisecond with a
large period, say 20 milliseconds, between each pulse,
it has been found that restraint and immobilization can
be obtained by the application of pulses and wave
forms other than those described.
Thus it has been found that by the application
of an alternating current of even sinusoidal wave
form is satisfactory to restrain an immobilized animal.
Also other wave forms such as a square wave, a triangular
wave, and the application of both unipolar and bi-polar
forms can be utilized to restrain the animal. Thus
it is to be realised that the invention is not limited
to the specific pulse formation as described as being
the optimum form, where it has been found that other
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. wave forms can produce satisfactory results without
~; detrimental affects to the animal.
In this respect also it has been found that a
pulse or alternative wave form is not essential but
- 5 that restraint can be applied by the application of a
; direct current to the animal, although it has been found
that the pulsating form is preferred.
In a further application of the invention micro
switches may be included in the line of the clip, so
that this forms an additional safety feature. Thus it is
possible now to apply the clips without any electrical
supply being provided to the clips themselves, and the
controls can be adjusted to give a minimum voltage of the
like, so that on switching on the micro switches at the
clips, the animal can be immediately restrained, and then
the control can be adjusted to give the required degree
of immobilization.
This is of advantage, for otherwise the animal
can sometimes be affected by a small electrical current
flow which would be annoying or aggravating to the animal,
which may struggle before the control is adjusted to
achieve the desired degree of immobilization, and hence,
with the use of the micro switches the animal can be
j immediately and instantaneously immobilized or restrained
without feeling any affects or build-up to this
- immobilizing degree.
The invention is of particular importance also for
immobilizing sheep to allow fully automated shearing
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; operations to take place.
Thus the immobilizing current may itself, be
utilized in assisting the positioning of a cutter by
sensing means. For example, this current through the
animal produces a field which can be sensed by a sensing
coil, and also an additional high frequency can be super-
imposed on the immobilizing current, and this high frequency
field can be sensed.
Furthermore a tuned coil can be used to sense the
proximity of the contour, the tuned coil being insulated,
so that the proximity of asurface causes the coil to be
detuned.
Also other proximity sensors can be used, such as
capacitance sensing, force, sensing or even force sensing.
Thus the invention can be applied to the immobilization
of animals in general, and while it is particularly adapted
to the use of animals of a domestic or agricultural
nature, it is to be readily seen that the invention is
also applicable to beasts and animals of any kind, and
for example, by utilising a device with a portable power
source, and some form of portable race or crush that
animals in the field or even in the wild state can be
driven into such a race or crush and then immobilized
for treatment, shearing or any other desired purpose.
