I. Field of the Invention
This invention pertains to ultrasonic testing apparatus for determining pregnancy in animals.  More particularly, this invention pertains to housings for such apparatus. 
II.  Description of the Prior Art
In the prior art, methods have been developed in the field of animal husbandry in which ultrasonic pulsing and detection have been used for detecting pregnancies in sows and other farm animals.  For many reasons, it may be economically important for a livestock producer to know if an individual farm animal is pregnant.  Such knowledge may be required in order to make a decision as to whether to market the animal, whether to start it on a special feeding program, or whether to rebreed the animal during the same season. 
Ultrasonic pregnancy detectors of the prior art include detectors having ultrasonic transducers which are placed against the abdomen of the animal to be tested.  For proper ultrasonic pulse propagation, the end of the transducer which is placed against the animal's abdomen is first dipped in water, mineral oil or motor oil before placing it against the animal's body. 
The prior art detection apparatus includes circuits for pulsing the transducer and processing echoes detected by the transducer.  The processed signals include an output which may be displayed to an operator either visually or audibly and which indicate the pregnant condition of the animal being tested.  An example of such a prior art apparatus with circuitry for performing the above tasks includes commonly assigned U.S. Pat.  No.  4,112,927 to Carlson dated Sept. 12, 1978.  As shown in the patent, the apparatus includes an instrument housing 10 with a probe 11 comprising an ultrasonic transducer 12 connected by means of an electrical cable 13 to the housing 10.  The patent discloses two methods of indicating the output to an operator.  The first is a visual display which shows an oscilliscope trace.  The patent also teaches circuitry for generating an audible tone in which, in the embodiment shown, a signal tone indicates a strong return signal from the animal's uterus while the absence of a tone indicates that the animal is not pregnant. 
While the apparatus described has been of value to the animal husbandry industry, certain difficulties are encountered in the use of the apparatus.  Namely, the animal under observation is often uncooperative and may be attempting to squirm away from the operator during the period of observation.  Indeed, the animal may attempt to attack the probe or the operator.  In addition to the adverse circumstances generated by the violence of the animal under observation, the environment in which the apparatus is used presents certain difficulties.  For example, the apparatus must be subjected to contact with mineral oil or the like which is used in the testing procedure as well as the often dirty environment of the test site due to animal waste and dust.  Finally, the livestock producer needs an apparatus which can be wielded easily by the operator while the operator is attempting to control the animal under observation.  Therefore, while the circuitry of the prior art has proved generally satisfactory, there is a need for improvement of apparatus housing to permit its ease of use by an operator while providing for protection from the adverse environment in which it is used.