Glossary

Ultrasound

A real-time imaging test that uses sound waves to show a dog's organs, heart and pregnancy without radiation.

Also called: ultrasonography, abdominal ultrasound, echocardiogram, echo, sonogram

Ultrasound uses high-frequency sound waves that bounce back from tissue and are turned into a moving picture. It shows soft organs such as the liver, kidneys, spleen, bladder, uterus and intestines, the thickness of their walls and any fluid or masses, which X-rays do not show well. An ultrasound of the heart is called an echocardiogram and measures chambers and valves.

The test uses no radiation and is painless. The fur over the area is usually clipped and gel is applied, and most dogs lie quietly, though some need mild sedation. It is also used to check for pregnancy in about the fourth week.

An ultrasound can guide a needle to take cell samples. It often adds to rather than replaces X-rays and blood tests, and image quality depends on the operator, so complex cases may go to a specialist.

Last reviewed November 8, 2026

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Related terms

X-ray An imaging test that uses a small amount of radiation to show a dog's bones, chest and belly organs. Biopsy The removal of a small piece of tissue, or a sample of cells, for examination under a microscope to find out what a lump or abnormal tissue is. Pyometra A life-threatening bacterial infection of the uterus in unspayed female dogs, usually in the weeks after a heat cycle, and a surgical emergency. Mitral valve disease A slow wearing of the heart's mitral valve that lets blood leak backward, the most common heart disease in older small-breed dogs.