Dog Ultrasound: How the Procedure Works and What It Shows

Name: Dog Ultrasound: How the Procedure Works and What It Shows
Creator: Dr. Zubair Khalid

By Dr. Zubair Khalid, DVM, MS, PhD · 2026-10-02

A dog ultrasound procedure uses high-frequency sound waves to build a live picture of the inside of your dog's body. It is painless, non-invasive, and usually does not require sedation. The images help your veterinarian look at organs, find the cause of symptoms, or check on a pregnancy.

This article is educational and is not a substitute for veterinary diagnosis or treatment.

Quick Answer

An ultrasound is a painless imaging test that uses sound waves, not radiation, to show soft tissues and organs in real time [1].
Most dogs do not need sedation, but some need a light sedative if they are anxious or painful.
Food is often withheld for about 12 hours before an abdominal scan so the stomach and intestines are easier to see. Water is usually allowed.
The fur over the area is usually clipped and gel is applied so the probe makes good contact with the skin.
A typical scan takes 20 to 45 minutes, and most dogs go home the same day.

What a Dog Ultrasound Procedure Is and Why It Is Done

An ultrasound machine sends short pulses of sound into the body. When those pulses hit tissue, some of the sound bounces back. The greater the change in speed between two tissues, the stronger the echo that returns [1]. The machine records how strong each echo is, how long it took to come back, and which direction the sound beam was aimed [1]. It then builds a picture that looks like a slice through your dog's body.

The sound beam sweeps through the body many times each second. That produces a moving, real-time image that changes as the veterinarian moves the probe across the skin [1]. This is why ultrasound is so useful for watching organs move, checking blood flow, and guiding a needle into a specific spot. The veterinarian can freeze any image and save it digitally, and short clips of the scan can be recorded too [1].

Ultrasound is best at showing soft tissue. That includes the liver, gallbladder, spleen, kidneys, bladder, pancreas, adrenal glands, lymph nodes, intestines, uterus, and heart. It can also examine muscles, tendons, and joints. A recent study of 48 carpi (wrist joints) in 41 dogs found that ultrasound could pinpoint which compartment was swollen and describe the soft tissue changes in detail [2]. Musculotendinous problems were the most common finding, seen in 30 of 48 joints (63%) [2].

Your veterinarian may recommend an ultrasound for many reasons:

Vomiting, diarrhea, or loss of appetite that does not improve
Blood work that shows liver, kidney, or pancreatic problems
A mass felt during a physical exam
Suspected bladder stones or urinary issues
Pregnancy checks
Cancer staging or monitoring a known condition
Checking that a catheter or tube is in the right place

One study of dogs having elective knee surgery found that abdominal ultrasound was more likely than chest X-rays to turn up a new health problem the owner did not know about [3]. That does not mean every dog needs a scan, but it shows how much information ultrasound can add.

If your dog is being checked for a possible pregnancy, the timing and what to expect are covered in Canine Pregnancy Diagnosis: Ultrasound and Hormonal Assays.

How to Prepare Your Dog for an Ultrasound

Preparation is simple, but it matters. A full stomach and gas-filled intestines block sound waves and make the image harder to read.

Food fasting. Your veterinarian will usually ask you to withhold food for about 12 hours before an abdominal ultrasound. This is standard practice, not a strict rule from a study. Water is normally fine to leave out. If your dog has diabetes or another condition that affects feeding schedules, call the clinic first so they can give you specific instructions.

Medication. Give regular medications unless your veterinarian tells you otherwise. Do not skip heart or seizure medication without asking.

Bathroom habits. A full bladder actually helps. The bladder is a fluid-filled structure that gives a clear window into the pelvis. Do not worry if your dog urinates before the visit, but try not to encourage a long walk right before the appointment.

Fur and skin. The probe needs direct contact with skin. For most abdominal scans, a patch of fur on the belly is clipped. If your dog has a thick or matted coat, the clipped area may be larger. Do not shave your dog at home. The veterinary team will do it safely and can show you how to care for the skin afterward.

Anxiety and sedation. Many dogs lie comfortably for an ultrasound with no medication at all. If your dog is very anxious, painful, or wiggly, a mild sedative may be used. The veterinarian calculates the dose from your dog's weight and health status. Tell the team about any previous reactions to sedation.

Timing. Plan for the visit to take longer than the scan itself. Check-in, clipping, the scan, and waking up from sedation (if used) all add time.

What Happens During the Procedure

Most scans happen in a quiet, dim room. Low light helps the veterinarian see the screen clearly.

Positioning

For an abdominal scan, your dog usually lies on their side or back on a padded table. A nurse or technician often holds a front leg or gently supports the body. For a chest or heart scan, your dog may stand or lie in several positions so the heart can be viewed from different angles.

Clipping and gel

The team clips the fur over the area to be scanned. They apply a water-based gel to the skin. The gel removes the air layer between the probe and the skin, because air blocks sound waves. The gel is warm and wipes off easily.

The scan itself

The veterinarian presses a handheld probe (also called a transducer) against the skin and moves it slowly. You may hear a whooshing sound from the machine. That is normal. The probe sends sound pulses and listens for echoes, and the computer turns those echoes into the image on the screen [1].

The veterinarian will often ask you to stay quiet so they can concentrate. Some clinics let you watch the screen and ask questions as they go. Others prefer to review findings with you after the scan.

Special techniques

Doppler shows blood flow through vessels and organs.
Elastography measures how stiff or soft tissue is. A study of 49 female dogs used a form of this technique to compare uterine and liver stiffness in healthy dogs and dogs with a uterine infection called cystic endometrial hyperplasia-pyometra [4]. Both uterine and liver elasticity values were significantly different between the groups [4]. This is still a specialized tool, not a routine part of every scan.
Contrast or guided procedures. Sometimes ultrasound is used to guide a needle for a fine-needle aspirate or a tissue biopsy.
Point-of-care scans. A quick bedside scan can confirm that a central venous catheter is in the right place. In a study of 15 animals (8 dogs and 7 cats), ultrasound agreed with X-rays 94% of the time for this purpose [5].

What the images can show

Ultrasound can reveal:

Fluid in the abdomen or around the heart
Enlarged organs, masses, or cysts
Stones in the bladder, gallbladder, or kidneys
Changes in organ texture that suggest inflammation or disease
Twisting of an organ. A 7-month-old Labrador with vomiting and lethargy had a "whirl sign" on ultrasound, which pointed to a twisted pancreas. Surgery confirmed pancreatic torsion, a rare problem in young dogs [6].
Adrenal gland size. A study comparing ultrasound and CT in 30 dogs found that CT consistently gave slightly larger measurements than ultrasound for all adrenal dimensions [7]. This matters when your veterinarian compares results over time. The same method should be used each time.

Ultrasound has limits. It cannot see through bone or air, so the lungs and bones are hard to evaluate. It also cannot replace X-rays or CT for every problem. Your veterinarian may combine tests to get the full picture. For a deeper look at how veterinarians read abdominal scans, see Ultrasonographic Evaluation of the Canine and Feline Abdomen: A Systematic Approach. For liver-specific findings, see Ultrasound of the Canine and Feline Liver and Biliary System: Normal and Abnormal Findings.

Recovery Timeline and Home Care

Ultrasound is not surgery. There is no incision and no general anesthesia in most cases. Recovery is quick.

Time after the scan	What to expect	What to do
Right away	Dog is awake and alert, or sleepy if sedated	Let them rest in a quiet spot
First 1 to 2 hours	Mild sleepiness from sedation may linger	Offer a small amount of water, then a small meal if fully awake
First 24 hours	Normal behavior returns	Watch the clipped skin for redness or irritation
1 to 3 days	Clipped fur starts to grow back	Keep the area clean and dry
1 to 2 weeks	Fur is noticeably regrowing	No special care needed
3 to 6 weeks	Coat looks close to normal	Nothing further required

If sedation was used, your dog may be unsteady for a few hours. Keep them away from stairs and furniture they could fall from. Do not let them swim or get bathed until they are fully steady.

The clipped patch may look pink or feel slightly stubbly. That is normal. Do not apply human creams or ointments unless your veterinarian approves them. If the skin looks red, raised, or weepy, call the clinic.

Most dogs eat and drink normally the same day. If your dog had a biopsy or a needle sample during the scan, there may be extra instructions. Follow those closely.

Possible Complications and Warning Signs

Serious complications from an ultrasound are rare. The procedure itself does not use radiation and does not hurt. The main risks come from sedation or from any needle procedure done during the scan.

Call your veterinarian if you see:

Trouble waking up from sedation, or extreme sleepiness that lasts more than a few hours
Vomiting that will not stop
A swollen, hot, or bleeding area where a needle was placed
Pain when you touch the belly
Trouble breathing
A fever (your dog feels warm and acts dull)

If your dog had a biopsy, some mild bruising or a small amount of drainage can be normal. Heavy bleeding, a growing lump, or a dog that will not eat the next day needs a call.

Questions to Ask Your Veterinarian

Before the scan, ask:

What are we looking for, and how will the results change my dog's treatment?
Does my dog need to fast, and for how long?
Will my dog be sedated?
Who will perform the scan, and who will read it?
How long will the appointment take?
Will the fur be clipped, and how much?
When will I get the results, and will I get a written report?
Is there a chance we will need a follow-up scan or another test?

After the scan, ask:

What did you find, and what does it mean?
Do we need a biopsy, blood work, or another imaging test?
What are the next steps if the scan looks normal but my dog still has symptoms?
Should we recheck this in a few weeks or months?

Write your questions down before the visit. It is easy to forget them in the exam room.

Limitations and When to Contact a Veterinarian

Ultrasound is a powerful tool, but it has real limits. It cannot see through bone or gas-filled bowel. It depends on the skill of the person holding the probe. A normal scan does not always rule out disease, and an abnormal scan does not always mean cancer. Your veterinarian puts the images together with your dog's history, exam findings, and lab work.

Contact your veterinarian the same day if:

Your dog vomits repeatedly or cannot keep water down
Your dog refuses food for more than 24 hours
You notice a new lump or swelling
Your dog seems painful when you touch the belly
Your dog is drinking or urinating much more than usual

Go to an emergency clinic now if:

Your dog's belly looks bloated and hard
Your dog is retching without bringing anything up
Your dog collapses, breathes fast, or has pale gums
There is heavy bleeding from a biopsy site
Your dog cannot stand or seems disoriented after sedation

Bring it up at a routine visit if:

Your dog has mild, on-and-off vomiting or diarrhea
Your dog is losing weight slowly
You want to discuss screening for a breed-related condition

Every dog is different. Your veterinarian is the only person who can examine your dog, review the images, and decide what is best for your pet.

Frequently Asked Questions

Does my dog need to be sedated for an ultrasound?

Most dogs do not need sedation. The scan is painless and many dogs lie still with a technician's help. Sedation may be used if your dog is very anxious, painful, or cannot stay still long enough for clear images.

Is an ultrasound painful for dogs?

No. The probe is pressed gently against the skin, and the gel is warm. Some dogs dislike lying on their back or having their belly clipped, but the scan itself does not cause pain.

How long does a dog ultrasound take?

Most scans take 20 to 45 minutes. A quick point-of-care scan can take just a few minutes, while a full abdominal study with Doppler may take longer. Plan for the whole visit to take about an hour.

Can I stay in the room during the scan?

Many clinics allow it. Ask when you schedule the appointment. Some veterinarians prefer a quiet room so they can focus, and they will review the findings with you afterward.

Will my dog's fur grow back after the ultrasound?

Yes. The clipped patch grows back over a few weeks. Most dogs look normal again within three to six weeks, though the rate depends on the breed and coat type.

Can an ultrasound tell if my dog has cancer?

Sometimes it can suggest cancer, but it cannot confirm it. A mass with certain features may raise concern, but a biopsy or needle sample is usually needed to make a diagnosis. Ultrasound helps your veterinarian decide where to sample.

Does an ultrasound use radiation?

No. Ultrasound uses sound waves, not X-rays or radiation [1]. That makes it safe to repeat as often as needed, including during pregnancy.

References

Ultrasonography in Animals - Clinical Pathology and Procedures. Merck Veterinary Manual.
Ultrasonography in Canine Carpal Disorders. Veterinary radiology & ultrasound : the official journal of the American College of Veterinary Radiology and the International Veterinary Radiology Association, 2026.
Abdominal ultrasound more commonly leads to the diagnosis of underlying comorbidities when compared to thoracic radiographs in dogs undergoing tibial plateau leveling osteotomy. American journal of veterinary research, 2026.
The effectiveness of uterine wall and liver elasticity and liver enzyme ratios in understanding the etiopathology of cystic endometrial hyperplasia-pyometra complex in dogs. Veterinary journal (London, England : 1997), 2026.
Point-of-care ultrasonography for verification of central venous catheter placement in cats and dogs. Frontiers in veterinary science, 2026.
Ultrasound Features of Pancreatic Torsion in a Young Dog. Veterinary radiology & ultrasound : the official journal of the American College of Veterinary Radiology and the International Veterinary Radiology Association, 2026.
Comparison of canine adrenal gland size assessment using ultrasonography and computed tomography. BMC veterinary research, 2026.