What is an ultrasound exam? — How are abdominal and cardiac conditions diagnosed?

ImmunityQ&AMeongsiljang Veterinary Advisory Board

This guide provides an easy-to-understand overview of the types of ultrasound exams for pets (abdominal and cardiac), the examination process, preparation steps, and the differences between ultrasound and X-ray imaging.

What is an ultrasound exam?

A dog and a cat on the examination table with an ultrasound probe

Ultrasound is a non-invasive imaging test that uses high-frequency sound waves, invisible to the human eye, to provide real-time views of your pet’s internal organs. One key advantage is that it requires no anesthesia and causes little to no pain, making it very comfortable for your pet. The two most commonly performed types are abdominal and cardiac ultrasounds, which can reveal internal organ structures and blood flow patterns that are difficult to assess with X-rays.

Abdominal ultrasound — What can be assessed?

Abdominal ultrasound is a diagnostic test that allows us to directly visualize the internal organs on a screen. The specific items we can assess vary by organ.

Liver and Gallbladder: We check for changes in liver size, gallstones, and gallbladder mucoceles.

Kidneys: We evaluate for stones, hydronephrosis (fluid accumulation in the kidney), and changes in kidney size.

Bladder: We check for stones, tumors, and changes in bladder wall thickness.

Gastrointestinal Tract: We look for foreign bodies, intestinal obstructions, and abnormalities in intestinal wall thickness.

Spleen: We check for tumors or splenic enlargement.

This detailed examination is actively used to identify the underlying cause when symptoms such as vomiting, diarrhea, loss of appetite, or abdominal pain are present. X-rays are often used first to get a general overview of the size and position of abdominal organs, while ultrasound is particularly useful for evaluating the internal structure of organs in greater detail. Therefore, these two tests are often used together in a complementary manner.

Echocardiography — The key test for heart disease

Echocardiography is a diagnostic test that evaluates the structure and function of the heart in real time. It is highlighted in veterinary cardiology textbooks as the most sensitive non-invasive test for diagnosing heart disease.

Ventricular wall thickness: Detects abnormalities in heart muscle, such as hypertrophic cardiomyopathy

Valve condition: Assesses valve diseases, including mitral valve insufficiency

Contractility: Determines reduced heart function, such as in dilated cardiomyopathy

Pericardial effusion: Identifies abnormal fluid accumulation around the heart

In particular, hypertrophic cardiomyopathy in cats often shows few early symptoms, so it is frequently detected only through echocardiography.

A cat's echocardiogram screen and a veterinarian

How is the exam performed?

We gently part the fur in the area being examined, apply a small amount of gel, and then place the probe (transducer) against the skin, moving it around to view the images.

Examination time: About 20–30 minutes for the abdomen, and 30–40 minutes for the heart.

Anesthesia: Usually not required. For particularly sensitive pets, a mild sedative may be used.

Pain: Minimal. It feels like gentle pressure from the probe on the skin.

Position: The exam is typically performed with the pet lying on its side or back.

Some clinics allow owners to stay by their pet’s side to help keep them calm, so it’s a good idea to ask about this when making your appointment.

A dog undergoing an abdominal ultrasound examination

Important points to check before the exam

Fasting before an abdominal ultrasound is essential for accurate results. If food remains in the stomach, it can obscure internal organs and hinder clear visualization. The exact fasting duration may vary depending on your pet’s condition and the purpose of the exam, so be sure to confirm the specific guidelines with your veterinarian when scheduling. Note that fasting instructions for cardiac ultrasounds may differ from those for abdominal ultrasounds, so it’s best to ask your vet in advance. Since the area being examined will need to be shaved, it’s advisable to schedule the ultrasound before, rather than after, a grooming session.

Ultrasound vs. X-ray comparison

Item	Ultrasound	X-ray
Areas that can be assessed	Internal organ structures, blood flow	Bones, organ size & position, lung condition
Real-time imaging	Possible (observe movement & blood flow)	Not possible (still image)
Anesthesia needed	Usually not required	Usually not required
Radiation exposure	None	Yes (very small amount)
Test duration	20–40 minutes	5–10 minutes
Suitable situations	Internal organ abnormalities, cardiac function assessment	Fractures, foreign bodies, lung & chest assessment

The two tests are complementary. Depending on the situation, they are often performed together.

When is an ultrasound exam needed?

Not every pet needs regular ultrasounds, but please consult your veterinarian if any of the following apply:

Chronic vomiting or diarrhea: If symptoms persist for more than two weeks, an abdominal ultrasound can help identify the underlying cause.

Detected heart murmur: If a heart murmur is heard during auscultation, an echocardiogram is necessary for a detailed assessment.

Seniors aged 7 and older: Including an abdominal ultrasound in your annual wellness exam can aid in early detection of potential issues.

Abnormal blood test results: Ultrasound imaging is useful for determining the cause when liver or kidney values are elevated.

Abdominal distension: An ultrasound allows for rapid evaluation if your pet has unexplained bloating.

A senior dog at the veterinary clinic with its owner

Breed-specific recommendations for regular echocardiography

Certain cat breeds, such as Maine Coons, Ragdolls, Sphynx, Norwegian Forest Cats, Siberians, British Shorthairs, and Devon Rexes, are known to have a predisposition to hypertrophic cardiomyopathy. According to veterinary cardiology textbooks, echocardiography is the most sensitive and specific test for detecting structural heart disease during breed screening, while screening based solely on auscultation has limited diagnostic value. Therefore, regular cardiac echocardiographic screening is recommended for predisposed breeds or kittens intended for breeding, and the timing and frequency of these exams should be determined in consultation with your veterinarian. For dogs, if a breed is suspected of having structural abnormalities such as mitral valve insufficiency, discuss the need for regular cardiac echocardiograms starting in middle age with your veterinarian. If you are planning to breed, pre-breeding cardiac echocardiography is especially important to check for phenotypic abnormalities in advance.

Reviewed by a veterinarian

Dr. Tony — Punnawat Phongkittirak

Veterinarian

A veterinarian who majored in veterinary medicine at Khon Kaen University, Thailand, and completed the IVSA program at North Carolina State University in the United States. Drawing on clinical experience at animal hospitals, he works in the pet healthcare field and is dedicated to building a digital care environment that connects pet parents with veterinarians.

Frequently asked questions

How can I find out the cost of an ultrasound examination?

Since costs vary significantly from clinic to clinic, it’s best to contact the clinic you plan to visit directly for the most accurate information. The price may also depend on the scope of the abdominal and cardiac examinations.

Does my pet feel pain during an ultrasound?

There’s hardly any pain involved. The shaving process might be a little uncomfortable, but the exam itself is just a matter of gently gliding the probe over the skin, so most pets tolerate it very well.

Is fasting absolutely necessary before an ultrasound?

Abdominal ultrasounds require fasting because residual food in the stomach can obscure internal organs, making accurate assessment difficult. The required fasting period varies depending on your pet’s condition and the purpose of the examination, so please confirm the specific guidelines with your veterinarian when scheduling the appointment. It is also advisable to ask your veterinarian in advance whether fasting is necessary for a cardiac ultrasound.

Can an ultrasound alone provide an accurate diagnosis?

Ultrasound is a powerful diagnostic tool that allows us to see the structure and function of organs in real time. However, for a definitive diagnosis, it is often used in combination with other tests such as blood work, X-rays, and biopsies.

Can cats undergo ultrasound examinations?

Yes, cats can receive the same examination. In particular, since hypertrophic cardiomyopathy is a common heart disease in cats, an echocardiogram is important. However, sensitive cats may require mild sedation.

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References

[1] Virginia Luis Fuentes et al., Textbook of Cardiovascular Medicine in Dogs and Cats, Ch. 11 – Echocardiography

[2] Silverstein & Hopper, Small Animal Critical Care Medicine, 3rd Ed, Ch. 43 – Echocardiography Indications

[3] Schaer & Gaschen, Clinical Medicine of the Dog and Cat, 4th Ed, Ch. 23 – Point-of-Care Ultrasound

[4] Burkitt Creedon & Davis, Feline Emergency and Critical Care Medicine, 2nd Ed, Ch. 14 – Cardiac Ultrasound in Dyspneic Cats