How Ultrasound Works

Ultrasonography involves passing a probe over your pet’s skin after the hair has been shaved away, while it emits harmless ultrasound waves (which are like sound waves, but at a higher frequency that we cannot hear). As the sound waves bounce off tissues and structures inside your pet’s body, they are detected by the probe and a computer converts this information into an image. This creates a moving, 2 dimensional image in real-time that looks like a slice through your pet’s body. Doppler is a feature on our ultrasound machine that detects movement. This identifies the blood vessels within an organ or structure, based on the movement of blood through them.


Ultrasound as a Diagnostic Tool

Ultrasonography is ideal for investigating disease within your pet’s abdomen. For example: If your pet has blood in their urine, an ultrasound can easily diagnose a bladder or kidney stone. If your pet’s examination and laboratory tests have indicated a problem with the liver, kidneys, prostate or intestinal system, ultrasound can help to narrow down the list of diseases that could be affecting that organ. If your pet has an abdominal mass, ultrasound can confirm this and determine what organ it is coming from as well as whether it might be possible to remove surgically. It can also be useful to look at other specific areas such as thyroid glands in the neck or lumps on the outside of the body. Ultrasound can be used to guide a less-invasive needle biopsy of an internal organ such as the liver, or an abdominal mass, and therefore avoid the need for a surgical approach. (A biopsy involves collecting a small piece of tissue to diagnose different types of liver disease, differentiate benign versus cancerous growths etc.)

Additional training and scanning experience is required for a veterinarian to be able to use ultrasonography effectively. Sometimes we will refer you to a specialist to perform your pet’s ultrasound if it is a difficult or complicated case.


The Ultrasound Process

Your pet may need to be fasted, or to arrive with a full bladder, depending on the area of study. He or she will be laid on a comfortable mattress with a soft blanket. For an abdominal ultrasound, your pet’s belly and sides will be shaved. Other areas of study often require shaving as well. This is necessary because the ultrasound probe must slide easily over your pet’s skin and it cannot ‘see’ through pockets of air that will be caught between the skin and fur. We will only shave the area necessary and no more – we know your pet didn’t ask for a haircut!

For an abdominal ultrasound, your pet will need to lie, on his or her side, with the help of an assistant who will gently hold him or her still. Halfway through, your pet will need to turn to the other side. Rubbing alcohol and ultrasound gel will be used to ensure the probe slides easily and help to get a good image. It is usually a calm and quiet experience in a dark room. Multiple still images will be recorded from your pet’s ultrasound scan for the medical record. All organs will be evaluated with an abdominal ultrasound, even if there is one specific area of interest. An abdominal ultrasound will take 45 minutes to an hour, depending on your pet’s cooperativeness as well as what is being investigated. It may be easier for you to leave your pet with us for part of the day so that you can go on to work or errands, or alternatively you can return at a prearranged time when we expect to be finished. If your pet is having just their urinary system or bladder scanned, it will take much less time. The veterinarian may need to spend a few more minutes reviewing images and taking some measurements before going over the results with you.



The veterinarian may ask your permission to give your pet sedation, if he or she is painful, very nervous, or if an ultrasound-guided biopsy is to be performed. Sedation is usually a combination of a drug for pain relief and a drug that makes your pet relaxed and sleepy. We only use sedation when it is absolutely necessary for your pet’s comfort or to ensure we can get ultrasound images that are useful. Sedatives and sedative/pain relief combinations are specifically tailored to your pet for the utmost safety, based on their temperament, body weight, age, other medical conditions and how relaxed your pet needs to be. Some sedatives can be reversed right away so that your pet will no longer feel the effects, but most will gradually wear off over 4-8 hours. The veterinarian will advise you if your pet needs to be monitored in the hospital after sedation or if he or she can go home right away.