The use of an ultrasound machine as a routine diagnostic test has become commonplace in veterinary medicine. Without getting into the weeds of medical physics, an ultrasound machine uses sound waves projected into a body cavity to generate an image. In veterinary medicine, an ultrasound is commonly performed on the abdomen to assess the various organs for possible disease.
Many veterinarians rely on an ultrasound when assessing a pet’s potential injury or illness. But, what does this really mean? In this article we hope to help you know what to expect when your dog needs an ultrasound.
How an Ultrasound is Performed
To perform an ultrasound, the pet is placed on a padded table on their back or side, and usually supported by two veterinary technicians. An ultrasound test is not innately painful, although we commonly apply some pressure to the area of interest, and some pets do not like this, so we typically give the pet a mild sedative to ease the pet’s anxiety. The area of interest typically needs to be shaved, although pets with very fine and short hair may be ok without a haircut. A combination of ultrasound gel and alcohol is generously applied to the area, and the ultrasound probe is then applied to the skin and moved around the pet to acquire images. While images are acquired for assessment later in the day, or at future visits for comparisons, we commonly think of ultrasound as a dynamic process, and we interpret our findings in the moment so the requesting veterinarian can immediately formulate next steps for the pet.
The process generally takes about 30 minutes, depending on the pet and complexity of the findings, and there is quite a bit of collaboration with other veterinarians as we work together to diagnose the pet’s medical condition, as well as determine the treatment options. Once the study is completed, the pet may be a bit sleepy from the mild sedative, but can usually go home soon afterwards, depending on if additional tests or treatments are needed. Occasionally, a pet’s skin can get red, and irritated from clipping the fur, and application of alcohol, but this is generally mild, and will go away quickly.
The Role of the Veterinary Radiologist in Helping Diagnose your Pet’s Injury or Illness
Specialist training in veterinary medicine has become more prevalent in the past few decades. As in human medicine, there is a group of veterinarians with specific training in radiology, sometimes called diagnostic imaging, to reflect the whole spectrum of modalities we are trained in. To become a Board-certified Veterinary Radiologist, one must complete initial training at a veterinary school, perform a general rotating internship to get a solid foundation in all facets of veterinary medicine, and complete a residency specifically in radiology, which typically require three or four years to complete.
In the residency training, the veterinarian is supervised by Board-certified Veterinary Radiologists, and taught about the various imaging modalities, such as ultrasound and MRI. This training is rigorous, and requires the study of topics including medical physics, radiation biology, pathophysiology, and diagnostic imaging acquisition and interpretation. This training culminates in a two-part board examination controlled by the American College of Veterinary Radiology (ACVR). Upon passing the board exam, the veterinarian becomes a diplomate within the college and is designated as Diplomate of the American College of Veterinary Radiology (DACVR).
What Does an Ultrasound Tell Us About Your Pet?
Ultrasound can be used to assess the thorax (chest). A heart-specific ultrasound test is called an echocardiogram, but we can also assess for possible lung disease or disease in the spaces around and between the lungs, neck, muscles and joints, eyes, and in some rare instances, the brain. An ultrasound is generally good at finding abnormalities, but unfortunately not great at diagnosing specific diseases. A common finding we see in dogs and cats are changes to the liver, such as being enlarged or abnormal in color. However, these findings are non-specific and can be seen with both benign (e.g. vacuolar hepatopathy) and neoplastic (e.g. lymphoma) disease processes. Assessing for gastrointestinal obstruction from foreign bodies ingested by pets is a common use of abdominal ultrasound, and is usually very good at finding these sites of obstruction.
When a puppy ate a box of screws, and a Golden Retriever ingested a rubber ducky, an Ultrasound helped the team at MedVet Cincinnati diagnose the problem.
The Benefits of Having a Study Interpreted by a Board-Certified Radiologist as a Member of your Pet’s Healthcare Team
A Board-certified Radiologist has had dedicated training in acquisition and interpretation of various imaging studies, including radiographs (i.e. “x-rays”), ultrasounds, and MRI studies. Our focus is solely on the imaging component of your pet’s care, which allows us to have a broad and deep knowledge base in the presentation of various diseases and provide this information to the primary veterinarian overseeing the case.
A boarded radiologist can help your family veterinary see more subtle lesions, and help diagnose your pet’s condition, and get them the help they need.
Ultrasounds are not the only Diagnostic Test; Others Include CT Scans, MRIs, and More.
The most commonly used imaging modalities in veterinary medicine are radiography (x-rays) and ultrasound, but we also have access to more advanced imaging modalities, such as computed tomography (CT or “CAT scan”), magnetic resonance imaging (MRI), and fluoroscopy (real-time radiography, which allows for dynamic studies, such as a swallowing study). We break down various diagnostic tests below.
- Orthopedic / Spinal X-Rays
An x-ray is commonly used to assess for a range of orthopedic disease ranging from planning for ACL surgery, diagnosing arthritis or potentially a bone tumor. Spinal x-rays can be performed to assess for possible trauma, infection, or tumors.
An MRI study is commonly utilized for patients with a neurologic issue, such as seizures, or being paralyzed. An MRI employs a powerful magnetic field to provide the best images to diagnose the brain and certain spinal cord disorders. Also useful in diagnosing certain musculoskeletal disease and less commonly abdominal imaging. This procedure requires anesthesia but is non-invasive.
CT studies have more broad utility, and may be recommended in patients with various diseases, such as a nose tumor or breathing problem. 3D images can be generated from the CT images, and a 3D model can be made in some cases to allow for surgical planning of complex cases.
The machines utilized for CT and MRI are typically human-level machines (multi-slice CT scanner or 1.5 Tesla MRI) and, at MedVet Cincinnati, we have dedicated team members trained to run these studies
- FNA (Fine Needle Aspirate)
One method of gathering further information about an abnormal finding from an ultrasound is to perform a fine-needle aspirate (FNA). A fine-needle aspirate involves using a small needle, similar to the size used for a flu shot in people, to pierce through the skin, and into the abnormal area within the abdomen, or other body with guidance from the ultrasound machine. This means we are watching in real-time as the needle enters the body cavity, and into the abnormal area. The goal of this procedure is to collect cells from the area of concern, which can then be placed on a slide, and reviewed by a pathologist. Veterinary Pathologists are Doctors of Veterinary Medicine who diagnose diseases by examining animal tissue and body fluids. This process is referred to as a cytology sample. Ultimately, we hope that this procedure allows the abnormal finding to be classified. For example, as cancer versus inflammation; however, sometimes, the sample we collect does not have enough information for the pathologist to make a determination as the cells may have been destroyed during the collection process, or we don’t get a representative sample from the abnormal area. If the cytology results are inconclusive, the veterinarian overseeing the case may recommend a biopsy of this abnormal area or may recommend additional testing.
In general, performing an ultrasound guided FNA is a safe procedure, and pets tolerate it well. However, there is a small risk of internal bleeding. In some cases, while we find abnormalities, sampling may not be required, or may not be possible, and a recheck ultrasound may be recommended. This will allow us to monitor these findings and potentially refine our thoughts on what is causing the abnormalities.
MedVet is Here to Help
If you have any other questions about ultrasound and veterinary digital imaging, ask your family veterinarian for more information We’re also happy to talk with you about your dog or cat’s health care needs should they be unavailable.
Chase E. Constant, VMD, Diplomate, ACVR is a board-certified Veterinary Radiologist at MedVet Cincinnati and MedVet Dayton. He has been a member of the radiology team since 2016. Dr. Constant earned a Bachelor of Science in Animal Science from the University of Wisconsin followed by a Doctor of Veterinary Medicine degree from the University of Pennsylvania School of Veterinary Medicine He completed a yearlong rotating internship in small animal medicine and surgery at Oradell Animal Hospital in New Jersey and a radiology internship at Oklahoma State University. Dr. Constant completed his radiology residency at the University of Tennessee College of Veterinary Medicine.
Dr. Constant was the recipient of the American College of Veterinary Radiology (ACVR) Resident Research grant to fund his project “Gadoxetate disodium (Eovist®) enhanced magnetic resonance imaging characteristics of hepatocellular carcinoma in dogs”. Dr. Constant became a Diplomate of the American College of Veterinary Radiology in 2016.