This invention relates to an anchor device for supporting an element within the vagina of a mammalian female.
The present invention is particularly, but not exclusively concerned with the mounting in a suitable location on a mammalian female of a temperature monitoring device which can be used to detect temperature changes indicative of estrus of the female to enable accurate timing of artificial insemination.
However the anchor device with which the present invention is concerned may be used for other purposes such as other telemetry devices or for drug release.
It is known that temperature changes can be used to predict the occurance of estrus in mammalian females. In cows a rise in temperature of 0.3 to 0.8 degrees celcius is usually found at estrus. Estrus has a duration of eight to twelve hours and occurs at roughly twenty one day intervals. If the cow does not conceive at first insemination, it is necessary to inseminate again at successive estrus until the cow does conceive. For this reason it is often necessary to continuously monitor the vagina temperature of the cow (to predict the occurance of estrus) for prolonged periods of time. Because vagina temperature varies due to factors other than estrus, it is necessary to compare vagina temperature to the rolling average of temperature for some days previous in order to make a decision as to whether the rise in temperature is significant.
Other devices are available for detecting estrus and one example comprises a pedometer which detects increases in animal movement which are also indicative of estrus. Other techniques for detection in the past have involved visual observation of the cow behaviour or the use of marker bulls which result in colour marking of the cow upon mounting by the bull during estrus. In some cases the level of progesterone hormone in the milk can be indicative of estrus.. Also some milking machines measure milk temperature and some claims are made that milk temperature can be used to predict the time of estrus. No commercial use of this method has apparently occurred.
Attempts have been made to manufacture an anchor device which can be located within the vagina of the mammalian female such as a cow. One example is shown in U.S. Pat. No. 4,387,724 (Zartman) and in U.S. Pat. No. 4,377,157 also of Zartman. These devices cannot support a telemetry device of a type comprising a radio transmitter of sufficient dimension to provide a receivable signal over a sufficient distance to enable continual monitoring of the temperature. A further device is known as the Heigro device (Agrophysics, San Francisco, Calif.) which was designed for long term residence in the heifer's vagina. In addition to these devices being unable to receive and support an element of sufficient size for remote telemetry, there is a severe danger that these devices will be expelled and in some examples up to fourty percent were expelled within the first month. It will be appreciated that in order for these devices to be commercially viable, it is necessary that the device remain in place for significant periods of time and also be reusable without the loss or damage which can occur if the device is expelled.
Up till now, therefore, there has been no anchor device available which enables the relatively large transmitter necessary for continual monitoring to be mounted within the vagina of the mammalian female and which enables the device to remain in position for extended periods of time.
In some cases this problem has been overcome by surgical techniques in which the telemetry device is mounted within an incision in the animal. This is of course however disadvantageous in that the surgical invasion is expensive and time consuming and is open to infection.
Attempts have also been made to detect temperature changes by a measuring device attached to the ear skin of the animal. However it has not been proven that ear skin temperature can be used to effectively detect estrus.