Note: Descriptions are shown in the official language in which they were submitted.
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"TELEI~ETERING ~AGINAL TEMPERATURE OF
FARM ANIMALS"
The present invention relates to ~he temperature
measurement of female 7i~estock.
Livestock breeder3, especially cattlemen, find that
one of their major concerns i5 that of being able to
maximize the conception rate of their females.
Dairymen have known for years that cow's body
temperature is capable of foretelling the onset of estrus
as well a~ conditions of poor health, like7 for example,
mastitis and other fever-inducing ailments. They also
knew that a cow's temperature varied greatly with ambient
conditions and were by no rneans the same from one animal
to the next even under identical condltions~ ~t has
therefore been recognized that a long term temperature
history of a particular cow related to the change in
ambient conditions would be very helpful in detecting the
small abnormalities in the temperature profile for a given
animal that are needed for a reliable prediction of estrus
or a febrile illness. Hitherto, there has not been an
effective way of obtaining this information.
Implantations of temperature probes in the ear canal
or rectum have not proved effective in Gbtaining
sufficiently accurate temperature readings necessary for
the rellable prediction of estrus or ill health. It has
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been determined that only temperature measurements taken
deep inside the body are sufficiently free of ambient
climatic factors and other external influences to a point
where the necessary de8ree of accuracy is attainable under
herd management conditions. Also, as a practical matter,
relatively long term implants are necessary since the herd
owner cannot afford the labour cost of having to take the
deep body temperature of each individual animal separately
at least once a day and preferably at the same time.
The best possibility for a true deep body temperature
reading essentially unaffected by external conditions
appears to be the vaginal canal, despite tests in human
subjects which have shown to the contrary. The difficulty
with probes implanted into the vaginal canal is that
muscular action tends to expel the probe relatively
quickly~
According to the invention, there is provided a
--fe ~
method of monitoring deep body temperature in -ffl~ffl~i~
'~h~ S t~ck
t~ ' ~m~ using a battery powered radio telemetric
temperature measuring device of a size adapted for
insertion into the uterine canal carried by an expandable
anchor of approximately the same size in collapsed
condition as said telemetric device~ said method
comprising collapsing the anchor and inserting it while
thu~ collapsed along with the telemetric device attached
thereto into the vagina to a depth where the assembly thus
formed li~s adjacent the cervixj expanding the anchor in
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sltu, and monitoring the temperature daily from a remote
external locatlon.
Further according to the invention, there is provided
a method for effecting long term intravaginal implantation
~c ~ a /~ v e s 7L o~
of a telemetric probe in m~ffl~ which comprises the
steps of: attaching a self-contained battery powered
probe adapted for insertion into the vaginal canal to an
expandable anchoring device of a size capable of being
introduced into the vagina in collapsed condition,
inserting the assembly thus formed into the vagina while
maintaining said anchoring device in collapsed condition,
and releasi.ng the anchoring device into its expanded
condition while thus implanted.
Still further according to the invention, there is
provided a device for intravaginal implantation in
-Fc ~7~a /c /, ve S 7~0C. /~
~m~i~r~e~, comprising an axially-extending hub
encircled by at least two rings of radially-extending
springable spine-like fingers co~operating with said hub
to define a multi-pointed star, a respective said star
being at each of the opposed extremities of the hub, the
hub being devoid of any projecting portion accessible to
the vaginal wall musculature to the extent that
contortions thereof would be effective to expel the
device.
The invention will now be described~ by way of
example only~ with reference to the accompanying
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diagrammatlc drawings9 in which:-
Figure 1 is a diagram showing placement of a probe
and an anchor therefor in the vaginal of the animal;
Figure 2 is a perspective view of the probe and
anchor;
Figure 3 shows a modified form of anchor; and
Figures 4 - 9 are charts detailing the long term
intravaginal temperature response of various species of
e ~ 7Lo ~
~'~' female ff~mm~.
Referring initially to Figure 1, the temperature
sensing probe used in the method is conventional and it
consists of a battery powered transmitter containing a
temperature-sensing thermistor which sends out a pulsed
signal, the rapidity of which corresponds to the
temperature of the transmitter and also the deep body
temperature of the animal when implanted in her vaginal
canal 12. The transmitter has been shown without detail
but approximately its actual size in relation to a grown
cow's vagina 12. The resulting signal is sensed at a
remote location outside the animal's body. The location
of the receiver is optional depending upon its sensitivity
and the strength of the signal generated, some receivers
being responsive to signals originating miles away from
the transmltter. The selection of slgnal strength and
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receiver sensitivity is a matter of choice well within the
skill of the art and will depend to a considerable degree
upon several extraneous factors such as the size of the
herd, the ability of the equipment to differentiate among
the several animals; the degree of confinement of the
herd, if any~ and other similar parameters.
The signal that is received is recorded and analyzed
during a preselected time period, say five minutes, at the
same or approximately the same time each day. In bovine
animals, for instance, it is a well-known fact that the
lowest body temperatures of the day occur early in the
morning between approximately 5:00 and 7:OO a.m~ The
baseline against which the spikes are most evident is
likely to be established d~ring such a time period;
therefore, for cattle at least, the measurements are
preferably made during this minimum baseline temperature
interval.
For small confined herds, tunable receivers are
unnecessary pro~ided the transmitted signal is relatively
weak. In such a circumstance, the receiver is placed in
reasonably close proximity to the particular transmitter
whose temperature signal is to be decoded so as to screen
out other extraneous signalsO On the other hand, care
should be taken to not excite the animal thus inducing a
false spike.
The battery powered radio transmitter containing the
temperature-sensitive thermistor is implanted at the mouth
of the cervix 14, where, for purposes of making dependable
and accurate prediction~, it must stay for at least one
complete e3trus cycle and preferably fifty days or
longer Because of the stress-induced fluctuations in
temperature, handling of the animal should be minimized;
however, a 50 day test performed at the proper time will
allow the animal to settle down while at the same time
provide good baseline temperature data against which the
spikes become easy to detect as will be apparent
presently. Notwithstanding the long term implantation of
the radio transmitter, it remains readily accessible to
service, repair and change batteries, all without having
to resort to surgical invasion of the animal or require
the services of a veterinary surgeon.
The act of implantation is a simple one capable of
being carried out by unskilled personnel using standard
techniques and instruments like, for instance, a trochar
tube and pushrod or plunger inside the lakter The
problems do not arise in connection with placement of the
probe but rather with how to keep it in place The muscle
contractions and relaxations of the vaginal w211s are such
that they quickly eject any foreign object like the probe.
The problem ~s solved by an expandable anchoring device
2~ which is introduced into the vagina and which yields under
the influence of the contracting vaginal muscles thus
preventing them from getting a sufficient hold to eject
either the anchor or the transmitter attached there~o back
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out through the vulva. One spider-like form of anchor
whlch has been used with good results is shown in Figure 1
and identified by reference numeral 10.
The anchor 10 is implantable using well~known
techniques within the vagina 1Z of a mammalian female at
the mouth of the cervix 149 the particular anatomy
illustrated being that of a cow or heifer, although the
animal could equally be a sow, a rnare7 or a ewe. The
method of implantation is simply one of collapsing the
radially~extending spider-like legs 16 emanating from the
hub l8 of each star 20 preparatory to placing same in a
speculum tube ~not shown) Upon insertion of such a tube
through the vulva opening 22 and ejecting the anchor from
such a tube by means of a pushrod or the like (not shown)
the placement of the unit is complete. Suitable
precautions are, of course, taken to insure that no injury
of the delicate tissue in the vaginal area takes place and
that the entire procedure is carried out under antiseptic
conditions.
As soon as the anchor 10 leaves the trochar tube; its
arms 16 spring open and assume the unfolded or expanded
operative condition shown in all three figures of the
drawings. As shown in Figures 1 and 2 in full lines and
in phantom lines in Figure 3, the anchor 10 is part of an
assembly 24 that includes, as discussed earlierJ a
conventional battery-powered radio transmitter 26
contalning a temperature sensing thermistor which sends
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out a pulsed signal and some means 28 for fastening the
latter to the hubs 18 intermediate the stars 20 on
opposite ends thereof~ The speculum tube must be sized to
accommodate the entire assembly while, at the same time,
remaining small enough to pass easily through the vulva
opening.
Fi~ures 1 and 2 to which detailed reference will next
be made both show the 2-star version of the anchor in
which identical stars 20 are spaced apart axially about
1.9 cms. with an axially-extending stem member 30 being
used to interconnect the hollow hubs 18 of the two stars.
As illustrated in Figure 29 the fastening means 28
comprises a short length of sterile cord or suture
material tying the transmitter to the exposed medial
portion of the stem. The 2-star version of the anchor 10
has proven quite satisfactory for use in heifers and small
cows .
The 4-star version of the anchor shown in Figure 3
comprises two additional stars 20C and 20D are interposed
between stars 20A and 20B found in both the 2-star and 4-
star versions. For the majority of heifers and cows the
4-star version is entirely adequate and should result in
essentially 100~ retention over extended period of time~
say 50 days and longer. In extreme cases such as an old
heavy cow~ the preferred anchor would be a 6-star version
(not shown). A 2-star unit has proven quite adequate as
an achoring device for holding small objects in the vagina
_ g
of cows, heifers and mares of reproductive age although,
to be on the safe side, the 4-star version ls preferable
for use ln the more mature females.
The anchor used is sim~lar to a vaginal device known
as the "Hei-Gro"*gwhich is u3ed to stimulate growth and is
described in U.SO Patent Specification 4,091,807. This
device comprlses a plurality of stars or spider~ and a
projecting cone and stem portion which extend rearwardly
from the rearmost star~ The device in this form does tend
to be expelled after a period of time which, although
sufficient for promoting growth, is insufficient to enable
long term temperature readings to be taken. It has been
found, surprisingly/ that if the projecting stem and cone
portion is removed, leaving only the stars and the
connecting portion of the stem therebetween9 then
virtually 100~ retention over extended periods of time (50
days or more) can be achieved.
The length of the arms 16 in the "Hei-Gro" unit
measured between opposite ends thereof seems to average
somewhere slightly in excess of 6 cm. The Applicant has
found that for smaller mammalian females like, for
exa~ple9 sows and ewes, a further modified unit having
stars with a radius of only about 3.5 cm. proved quite
adequate although it i5 preferred that the radius should
be at least 3.5 cm, the overall axial length of the
device being about 4 cm~ As a matter of fact, the full
size 2-star modified unit apparently was too large to be
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lnserted all the way to the entrance of the cervix ~ince
it remained clearly visible at the vulva opening.
Accordingly, the Applicant has modified the
commercially available "Hei~Grol' growth promotion device
so as to convert the latter to anchoring device capable of
holding small obJects in situ within the vagina of
mammalian females of various species and ~izes for
prolonged period of time while, at the same tlme leaving
their normal reproductive functions unimpaired.
Once the temperature sensing probe is in place as
shown, the herd manager or other investigator can begin
gathering data for the purpose of ascertaining when the
animal is in condition to conceive or7 alternatively, is
not ovulating and cannot be impregnated. This same data
will be effective to indicate the onset of a febrile
illness well before any overt clinical signs becomes
apparent. The results of actual deep body temperature
measurements in three species of female livestock mammals
form the subject matter of the graphs appearing herein as
20 Figures 4 - 9, inclusive, to which detailed reference will
soon be made; however9 before doing so, it is appropriate
to explain more about when the probe should be implanted
and why it should be kept in place for an extended period
of time.
Cows and other female animals are known to have
cyclic variations in basal body temperature which cycle
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bears a relationship to the estrous cycleO This cycle was
discovered to differ a great deal from that of the human
female. One major difference is the fact that women
experience a near constant temperature pattern from
period-to-period, whereas, cattle and other animals do
not. The fact of the matter is that farm animals exhibit
a changing temperature pattern which seems to depend to
some degree at least upon the climate and the season. For
instance, it can be demonstrated that the normal body
temperature baseline takes on an ascending pattern during
prolonged periods of cold weather and a descending one
when it is warm. It is essential, thereforel that a
fairly long term history of not less than a complete
estrous cycle and preferably even longer, say 50 days, be
kept and used as the basis for detecting any significant
changes such as those that signal ovulation or the onset
of febrile illness.
In the human female, despite the constant temperature
pattern between periods, ovulation based upon deviations
from this pattern cannot be reliably detectedO
Nonetheless, and con~rary to what one might expect,
readily detectable temperature spikes signalling ovulation
do occur in farm animals. Even though the baseline
temperature varies seasonably and with environment
conditions, it has been discovered that ovulation can be
reliably ascertained provided a sufficient temperature
history leading up to the anornaly or spike is available.
The proof is, of course, that animals bred on such a spike
get pregnant while those bred at other times do not~
More specifically, the estrus cycle is s~ch that a
pronounced spike in the order of 0.8C is noted on the day
of estrus in a COW9 for example, while an equally
prominant dip in temperature takes place on the preceding
day and again on the following day when ovulation occursO
This cyclic pattern happens in cows with so-called "silent
heats" as well as those with normal heat periods. This
o.8 spike lasts for one day only and it is detected by
measuring it against her average body temperature over the
preceding ten day period or thereabouts.
In a dairy herd, for example, a cow's greatest milk
is produced provided she is inseminated wikhin 90 days
after ~arturition; yet, statistics show that about one-
third of all dairy cows miss this target for the reasonthat over 40% of these cows never haYe a heat period
recorded within the first sixty days after they have
calved and an additional 12~ or so go over ninety days.
Even after the first heat period following parturition is
recorded9 about one in every six thereafter is missed.
For these reasons alone, it i5 of the utmost importance if
cost-effective dairy herd management is to be achieved,
that each of these heat periods~ and preferably the first,
is reliably detected~
Turning the attention next to the graph of Figure 4,
whereln Mare I showed four spikes (A, B, C and D~ that
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surpassed a threshold line (spike indicates about 3/4C
above mean). These spikes are spaced at regular intervals
that coincide with the expected time between ovulations~
Also9 spikes A, B and D were associated with estrus. The
mare was not teased during the period of spike C, so that
estrus status is now known. Each data point (dot)
represents a once-daily reading taken at approximately
7:30 a.m. between May 9 and August 12, 1979~ The ordinate
scale is in radio counts per 5 minute period.
Mare II charted in Figure 5 showed four substantial
temperature spikes (magnitude about 3/4C above mean)
which extend above the threshold line. Spikes B and D
occurred at the last day of the estrus period. The mare
was not teased during the period of spike A, so her
receptivity is not known. The spike C occurred during
mid-estrus and, curiously, no spike appeared during the
subsequent estrus period. Each data point (dot)
represents a once-daily reading taken at approximately
7:30 a.mO between June 1st and August 10, l979. The left
side scale is in radio counts per 5 minute period.
The intravaginal temperature graph of Figure 6 was
taken of a sow instead of a mare. The sow exhibited two
heat periods of 2 days duration which is characteristic of
sows. There were temperature spikes (A and C) towards the
end of each heat period. The sow was accidentally bred on
the second day after spike C and became pregnant. Spikes
A and C were nineteen days apart which matches exactly the
3 ~
normal ovulation interval for sows~ Spike B was quite
high and lndicates a fever of short duration which might
well have been due to a mold infection such as a virus
might cause.
Directing the attentlon next to Figure 7, heifer 1474
initially experienced three normal heat periods and there
were temperature spikes (A and B) recorded as shown. The
transmitter was not implanted in the heifer during the
period marked xxx. Spike C was not accompanied by
standing heat, however~ the interval was normal to the
previous spike and the heifer was bred. It is believed
that she became pregnant and then miscarried because she
came in heat 28 days later with a spike occurring the
subsequent morning. The 29 day interval was too long for
15- normalcy. Eventually, the heifer was bred again during a
heat and spike episode and she became pregnantO
Figure 8 to which reference will next be made details
the temperature pattern of yet another heifer. Heifer
1494 presented spikes A, B and C during her test period~
She was just reaching puberty when brought into the
experiment. She only expressed heat once and that was
accompanied by spike B; nevertheless, she did have normal
intervals between the three significant spikes. Following
spike C she did not show any mating behaYious or spikes
during a perivd of very hot weatherO Eventually1 she did
come in heat and had a smaller spike~ She was bred and
became pregnant.
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Finally7 with reference to Figure 9, a cow 590 was
selected because of her lnfertility as a subject for
examination of spike condltions during known reproductive
insufficiency. There were two very high spikes without
associated heat. She had a quentionable heat once and a
definite standing heat towards the end of the observation
period. The cow was bred and spike B and did not become
pregnant. Apparently~ the cow is physiologically out of
phase and there was no normal periodicity in her record at
all. This example clearly illustrates the value of the
remotely-sensed temperature method of the present
invention in detecting acyclicity and probably ovulation
f`ailure.
On the whole, the foregoing charts clearly reflect
the day-to-day physiological conditions of the subjects.
When her temperature reading is noticeably greater than
her previous ten day average and exceeds all previous
highs during that time interval, the probability is that
she is preparing to ovulate and she should be bred on
either the day of the estrus spike or early the next day.
In the specific case of COW5; if the foregoing temperature
spike falls on a 21 +/- 5 day interval from the preceding
spike, the cow is very probably ovulating; however~ if
the spike is out of phase with the normal estrus cycle as
above noted and has a magnitude somewhere around three
times ~he magnitude of previous spikes, the animals is
very probably feverish and such a spike signals the onset
of some febrlle illness rather than estus and at a time
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well in advance of when any clinically recognizable
symptons appear. The random occurrence of such spikes,
their magnitude and duration (more than one day), allow
the observer to readily differentiate between the fever
spike and the estrus spike. It is also significant to
note that the failure to record a spike is equally
informative because it signals the absence of ovulation
which is every bit as important to know as when the animal
is experiencing normal ovulation tsee Figure 9)
The foregoing examples clearly demonstrates that,
while the temperature cycle of various species of female
farm animals have- long been recognized as effective
indicators of estrus, until now there has never been a
reliable9 practical and effective method for determining
the animal1s temperature, deep body or otherwise, on a
daily basis under herd management conditions~ The method
permits the long term monitoring of the deep body
temperature of a female mammal without having to handle
her over and over again. The subject is natural at all
times and need not be agitated as is the case with present
deep body temperature measurement methods where the
thermometer or other type of temperature measurement probe
is repeatedly inserted and removed from her rectum or
vulva every single day. The animal is not harmed in any
~ay or otherwise traumatized yet she is constantly
providing the observer with much needed information on her
physical condition which is otherwise essentially
unattainable under field conditions
3 ~
Summarlzing~ the method and device described above
solves three heretofore unsolved problems, namely: 1) it
provides for remote interrogation and possibly even
automated monitoring of an animal's deep body temperature
by means of an indwelling probe implanted without surgery
2) it provides information on ovulation on all animals~
both those experiencing active estrus and those who are
not; and 3) it detects feverish conditions in advance of
clinical illness~
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