In order to obtain high-quality images, the end of the probe needs to be coated with coupling gel or lubricant. This allows ultrasound to penetrate animals, as these waves cannot pass well through the air space between the transducer and animal skin. The coupling gel shall have sufficient fluidity to remain on the probe and animal skin when contacted without repeated use. The thicker gel provides less air interference and results in better transmission of ultrasound to the skin. The best coupling substances can usually be found through repeated experiments. However, although some substances may appear to have the desired properties, some of them can reduce image quality, damage transducers, or cause premature degradation of RTU components.

The use of animal B-ultrasound machine to detect pregnancy in sows needs to be conducted in a pen. The surface of the probe is lubricated and used to contact the abdomen located outside the nipple line and in front of the hind legs. In standing sows, the uterus of early pregnancy is located directly in front and below the pelvis. The probe should be aimed at the other side of the spine at a 45 degree angle, slightly tilted towards the sow's head at 10 to 20 degrees, and then slowly rotated in a small 45 degree arc. This scanning program can quickly observe multiple fluid bags in the uterus, and each animal usually only needs 5-10 seconds to confirm the presence of the fluid bags. Both 3.5 and 5.0 MHz transducers can easily penetrate this distance to achieve good imaging. If the animal is in a loose house and then leaves,