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Equine Health Resource

Ultrasound, Trans-Abdominal for Colic, Generally



Ultrasound is extremely useful for imaging the horse’s abdomen in cases of abdominal pain or suspected abdominal disease.

Ultrasound produces sound waves that pass through the tissues and bounce back to the transducer at different speeds, depending on the density of the tissues it passes through. This pattern is converted into an image by a computer.

The hair is wet well with alcohol to allow the ultrasound beam to penetrate the hair coat. The ultrasound probe is placed in particular locations and through a particular exam sequence to visualize the accessible structures. Horses with heavy coats may need to be clipped. The size, location and tissue appearance all are evaluated.

The left and right kidneys, liver, spleen, stomach, small intestine, large intestine, bladder, body wall, peritoneal space can all be evaluated to some degree.


This is a fast and noninvasive test that allows a detailed view of soft tissue structures.

Easily differentiates fluid from different tissues and shows intestinal movement in real time.


Even the most powerful, penetrating ultrasound machines and probes can only penetrate about 40cm into the abdomen - about 15". Most give good resolution at only about half that. Because of this, much of the abdomen cannot be visualized.

Lower power machines with high frequency probes may only penetrate a few inches and provide limited information.

Ultrasound cannot penetrate gas (air) or bone. If the intestine has large amounts of gas in it, it may block the ultrasound beam from deeper structures.

Helpful Terms & Topics in HSVGWritten, Reviewed or Shared by Experts in Equine Health

Author: Doug Thal DVM Dipl. ABVP


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