What Is Pet Imaging Used For? X-ray, ultrasound, and CT
Pet imaging is used to see inside a dog or cat without surgery: to find fractures, swallowed objects, tumours, fluid, organ changes and the cause of pain or vomiting that an examination alone cannot explain. Vets use X-ray for bone and chest, ultrasound for soft tissue, and CT for detailed 3D views of the head, spine, lungs and complex cases.
What is pet imaging used for? Answering the question of what is going on inside an animal that we cannot see or feel from the outside. A vet can palpate a belly, listen to a chest and check a limb for pain, but none of that shows a fractured pelvis, a tennis ball in the stomach or a mass on the spleen. Imaging does. In practice, that means three tools. X-rays for bone, chest and anything dense. Ultrasound for organs, fluid and the gut. CT when a flat picture is not enough, or when the problem is in the skull, spine or lungs.
One clarification, because Google mixes these up. This article is about diagnostic imaging for pets (dogs and cats), not PET scans, the nuclear medicine test used in human hospitals.
What is pet imaging used for most often?
In an emergency hospital, the most common reasons are trauma, vomiting that will not stop, breathing difficulty, a pet that cannot urinate, and the suspicion that something has been swallowed. In general practice, the list shifts toward lameness, unexplained weight loss, abnormal blood results and lumps that need staging before anyone decides on surgery.
Finding the cause of pain. A limping dog might have a fracture, a torn ligament, arthritis or a bone tumour. They can look identical on examination and completely different on film.
Locating swallowed objects. Bones, stones, toys, corn cobs and fabric. Some show on X-ray, some only on ultrasound.
Checking the chest. Heart size, fluid in or around the lungs, tumours, and the cause of a cough or laboured breathing.
Looking at organs. Liver, kidneys, spleen, bladder, adrenal glands and gut wall thickness, plus guiding a needle to take a sample.
Staging cancer. Where a tumour is, how big, and whether it has spread. This drives every treatment decision that follows.
Planning surgery. Surgeons want to know exactly what they will find before they open an abdomen or repair a complex fracture.
X-rays: bone, chest and anything dense
Digital radiography is the fastest and most widely available form of pet imaging. It works by passing a small dose of radiation through the body, while dense structures like bone and metal block it and appear white, air appears black, and soft tissue sits somewhere in between.
That makes X-ray the first choice for suspected fractures, dislocations, chest assessment and many foreign bodies. It is less useful for telling one soft tissue from another, which is why a vet who suspects a problem in the liver or gut wall will usually move to ultrasound. Most X-rays take a few minutes. Many pets have light sedation so they hold still and nobody has to wrestle an animal that is already in pain.
Ultrasound: soft tissue in real time
Ultrasound uses sound waves, not radiation, and shows moving pictures of the inside of the abdomen or chest as the probe is moved across a shaved patch of skin. Vets use it to examine each organ in turn, measure them, look for masses, spot free fluid, watch the gut moving, and check the heart's chambers and valves (an echocardiogram).
It is the workhorse for vomiting, diarrhoea, abdominal pain, abnormal bloods and unexplained weight loss. It is also how a vet guides a fine needle into exactly the right spot to collect cells or fluid for the laboratory, which often gets a diagnosis without surgery. Most dogs and cats tolerate it awake or with mild sedation.
CT scans: when a flat image is not enough
Computed tomography takes hundreds of thin X-ray slices and stitches them into a three-dimensional picture. Overlapping structures that hide each other on a normal X-ray, such as the nasal passages, the inner ear, the spine and the lungs, become clear. CT is the standard for chronic nasal disease, head trauma, complex fractures, some spinal problems, lung tumours and cancer staging before surgery or chemotherapy.
Because the animal must stay perfectly still, a CT scan for a dog or cat is done under sedation or a short general anaesthetic. At VECA, the scanner is at the Campbelltown hospital, and where the case calls for it, the images are sent to board-certified veterinary radiologists for a formal report. Not every hospital has one. In Sydney, many GP vets refer patients to a hospital with a scanner for a same-day outpatient CT.
What happens on the day, and will my pet be sedated?
On the day, you can expect an examination, an estimate and a conversation about sedation. Nothing is scanned until you have agreed to the estimate.
Sedation is common and not something to be alarmed by. A stressed animal that keeps moving produces blurry images and repeat films, which means more radiation and more time. Light sedation for X-rays and ultrasound wears off within a couple of hours. CT requires a general anaesthetic, so your pet will be fasted beforehand, monitored by a nurse throughout, and kept in the ward until fully awake. Plan for a day admission.
Results from X-ray and ultrasound are usually discussed with you at the same visit. Formal radiologist reports on CT take longer, though anything urgent is acted on immediately. A copy goes to your regular vet either way.
How much does pet imaging cost in Australia?
Cost depends on the modality, how many body regions are imaged, whether sedation or anaesthesia is needed, and whether a specialist radiologist reads the study. As a rough public benchmark, Sydney and Melbourne hospitals that publish their prices list CT for dogs and cats from around $1,400 for the scan alone, up to $2,500 for one body region including anaesthetic and radiologist report, with complex studies reaching $4,000. X-rays and ultrasound are considerably less.
At VECA, emergency patients pay a $199 consultation first, with no after-hours or public holiday surcharge, and imaging is quoted on top before it happens.
Australians spent an estimated $1.9 billion on veterinary services in 2025, and around one in six cat and dog owners admitted to deferring vet care to save money. With imaging, delay tends to cost more: a foreign body found at hour two is a simpler procedure than the same object found at day three with a perforated gut. If money is tight, say so at the front desk. Staged diagnostics, payment plans such as VetPay and Afterpay, and on-the-spot GapOnly insurance claims exist for exactly that reason.
When is pet imaging urgent?
Same-day, and often same-hour, if your pet has been hit by a car or had a serious fall, is straining to urinate without producing anything (especially male cats), has a swollen or hard abdomen with retching (possible bloat), is struggling to breathe, or has swallowed something and is vomiting. These are the cases where imaging changes what happens in the next hour, not the next week.
Imaging can wait for a booked appointment when the problem is chronic, and your pet is otherwise well: a long-standing limp, gradual weight loss, a lump that has not changed, or a follow-up scan for a known condition. Your regular vet is the right person to decide which bucket your pet falls into. If it is after hours and you are unsure, an emergency hospital would rather take the call than have you guess.
Frequently Asked Questions
Is pet imaging safe for my dog or cat?
Yes, with sensible precautions, the radiation dose from a diagnostic X-ray or CT is low and one-off, and ultrasound uses no radiation at all. The main risk with imaging is the sedation or anaesthetic, which is why hospitals run pre-anaesthetic bloods, monitor throughout and tailor the drugs to your pet's age and condition. Your vet will discuss risks for your animal specifically.
Why did the vet do an X-ray and then want an ultrasound as well?
Because they show different things. X-ray is good at showing bone, air and dense objects but poor at telling one soft tissue from another. If the X-ray suggests a problem in the abdomen without pinpointing it, ultrasound is the natural next step to look at each organ in detail. Using both is normal practice, not a sign the first one was wasted.
Can my regular vet send my pet somewhere just for a CT scan?
Yes. Many GP vets in Sydney refer patients for an outpatient CT at a hospital with a scanner, such as VECA Campbelltown. Your pet goes in for the day, is scanned under anaesthetic, recovers and goes home, and the images and radiologist report go back to your own vet, who keeps managing the case. You do not need to change vets to get the scan.
What does it mean if the imaging comes back normal?
It means the structures looked at appear normal, which rules out a lot and is useful information. It does not mean nothing is wrong. Some conditions affect function rather than structure, so bloods, a biopsy or a repeat scan later may still be needed. A good vet will explain what a normal result has excluded and what the next step is, rather than leaving you with a shrug.
If your pet needs imaging urgently, VECA's hospitals at Campbelltown and Rouse Hill are open 24/7. Call Us Now on (02) 9129 5888.
About the Author
Dr Phil Hayton, Emergency & Critical Care Veterinarian at VECA
Article Reviewed & Approved by Dr Phil Hayton, Emergency & Critical Care Veterinarian at VECA. Dr Phil Hayton is an Emergency and Critical Care Veterinarian, working in Client Relations at Veterinary Emergency Care Australia (VECA). He has experience across emergency medicine, critical care and veterinary diagnostics, including a professional background in veterinary virology. He is passionate about clear communication, client advocacy and helping pet owners navigate difficult decisions about their animals' care.
Sources
References for statistics and claims cited in this article.
Animal Medicines Australia, Pets in Australia: A national survey of pets and people 2025 (media release, 18 September 2025): $1.9 billion annual spend on veterinary services. 14% of dog owners and 18% of cat owners deferred or reduced veterinary care | https://animalmedicinesaustralia.org.au/news-and-media/australias-most-comprehensive-pet-survey-shows-nearly-three-quarters-of-australian-homes-now-have-a-pet/
North Richmond Veterinary Hospital, CT imaging costs: dogs and cats from $1,400 | https://northrichmondvet.com.au/ct
Advanced Vet Care Lane Cove, CT scans for dogs and cats (July 2026): anaesthetic and CT of one body area $2,500 including radiologist report | https://advancedvetcarelanecove.com.au/x-rays-ultrasound-and-ct-scans-for-dogs-and-cats-7-days-a-week/
Tooronga Veterinary Clinic, CT scans for pets in Melbourne: typically $2,000 to $4,000 including day stay and general anaesthesia | https://www.toorongaveterinary.au/ct-scans
VECA, Diagnostic Imaging and Emergency pages (services, sedation, radiologist review, $199 emergency consultation) | https://www.veca.com.au/imaging
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