Abdominal Ultrasound

An abdominal ultrasound lets us look inside the organs of the abdomen. A blood test tells us whether an organ is working; ultrasound shows what that organ looks like. Used together, the picture becomes clear.

The study is painless, needs no anaesthesia, and is done with the animal held calmly on its back or side.

What is assessed

• Liver and gall bladder: size, tissue texture, masses, biliary sludge and stones
• Kidneys: size, structure of cortex and medulla, cysts, stones, dilation
• Bladder: wall thickness, stones, sediment, masses, clots
• Spleen: size, texture, masses
• Stomach and intestines: wall thickness, motility, obstruction, foreign bodies, one loop telescoping into another
• Pancreas: signs of inflammation
• Adrenal glands
• Uterus and ovaries: pyometra, pregnancy, masses
• Prostate: enlargement, cysts, abscess
• Lymph nodes and free fluid in the abdomen

Doppler adds blood flow within the vessels.

When it is asked for

Ultrasound is not a screening tool; it is a study that answers a question. It is most often requested for:

• Repeated vomiting or diarrhoea that will not settle
• Suspected foreign body and signs of obstruction
• Raised kidney or liver values on a blood test
• Urinary problems, blood in the urine, suspected stones
• Unexplained weight loss or loss of appetite
• Abdominal swelling, fluid, or a mass that can be felt
• Searching for a source of fever
• Suspected pyometra in an unspayed female
• Monitoring a pregnancy
• As part of regular checks in an older animal

Preparation

Fasting matters most: six to eight hours without food gives a markedly better image, because gas in the stomach and intestine stops the beam passing. Water is not withheld.

If the bladder is to be assessed, a full bladder is easier to see, so not walking the dog immediately beforehand helps.

The abdomen is clipped. This is not an optional detail: air trapped between hairs degrades the image, and a result from an unclipped study is not reliable.

What ultrasound cannot see

It is worth being straightforward about this.

Anything behind gas-filled bowel is hidden. The inside of the lungs cannot be assessed by ultrasound, because air stops the beam; the chest needs radiography. Bone structure is not what ultrasound is for. Whether a mass is benign or malignant cannot be told from the image alone; that needs a needle sample or a biopsy.

So ultrasound is usually used alongside blood tests and, where needed, radiography. Which test is asked for and why is described on the internal medicine page.