Ultrasound for Breeding

In the modern equine veterinary practice, ultrasonography is used to determine the ovarian structures present on a mare, the readiness of the uterus for breeding, presence of fluid in the uterus, uterine infections and pregnancy.

It is necessary to use ultrasound to determine the proper time for breeding:

• Mares that don't show estrus
• When there is no access to a stallion to determine estrus
• Mares with young foals
• Mares being bred with frozen semen
• To determine multiple ovulation

The ultrasound works by emitting high frequency sound waves. As the sound waves move through the tissue, some are reflected back to the transducer, converted to electrical current and displayed on the screen. The number of waves reflected is proportional to the density of the tissue. As sound waves pass through fluid, few waves are reflected and the screen appears black. As the sound waves pass through tissue, waves are reflected back and the screen appears gray.

The frequency of the sound waves generated by the transducer determines how far the sound waves will penetrate into the tissue. Lower frequency transducers (3 and 3.5 MHz) are used to image structures like the lungs, heart or kidney. High frequency transducers (5 to 7.5 MHz) are used to examine the reproductive tract.

The animation further explains how the ultrasound works.