What is Veterinary Diagnostic Imaging?

Veterinary diagnostic imaging includes radiographs (x-rays), ultrasound, MRIs, and CT scans, all of which are used as diagnostic tools to collect information on your dog's health. The vast majority of imaging is non-invasive and completely painless. However, some imaging may require sedation or even anesthesia because the dog must be kept still to allow for adequate images to be produced. Veterinarians use these images to collect information on your dog to help them to make a medical and sometimes surgical plan.

When Is Veterinary Diagnostic Imaging Necessary?

After your veterinarian has examined your dog, he or she may want to begin to collect more information that will lead to a diagnosis and then, a treatment plan. X-rays are usually the first line of imaging. The x-ray may lead to a diagnosis which allows them to move forward with a plan. However, sometimes the next step may be ultrasound to get a more thorough or specific look at a particular area of the body.

For instance, if your dog is vomiting and feeling ill, your veterinarian may take an x-ray to look for possible causes such as obstruction of the intestines or an obvious foreign body. The x-ray may show some signs of an intestinal obstruction, however, before proceeding to surgery, it would be prudent in some cases to follow with an abdominal ultrasound. The ultrasound will give more detail of the questionable area and therefore allow more confidence of the treatment plan to move forward with surgery. Occasionally, x-rays and ultrasound allow for a definitive diagnosis but other times they will simply add more information to help put the puzzle together for the best treatment plan for your dog.

The four types of Veterinary Diagnostic Imaging our veterinarians may utilize to assist in the diagnosis of your dog's condition are:

  • X-Rays
  • MRIs
  • Ultrasounds
  • CT Scans

More information on each of these types of radiographs is provided below.

X-Rays

Dog x-rays have been in use throughout the medical community for many decades. Dog x-rays are by far the most regularly used form of diagnostic imaging in the veterinary industry because they are cost-effective (comparatively speaking), and they can accurately diagnose the state of skeletal structure and composition, large body cavities, and the presence of many foreign objects. Dog x-rays are totally painless, but some dogs can benefit from sedation to reduce anxiety and stress.

Dog x-rays usually proceed as follows:

  • The dog is placed on the x-ray table
  • A technician positions the x-ray machine so that the x-ray beam targets only the area of interest
  • Modern x-ray equipment allow for low levels of radiation and when used only occasionally are perfectly safe for your dog
  • Because dog x-rays are static images, the procedure usually requires less time than a procedure like an MRI

Dog x-rays have traditionally been captured on actual film, and still can be when necessary. However, our x-ray images are now digital which allows us to capture the images on a secure server that our veterinarians can access at any time, and can also share with specialists, if necessary.

Ultrasounds

A dog ultrasound is the second most common type of diagnostic imaging tool veterinarians use to diagnose a dog's medical condition. Ultrasounds use soundwaves to examine and photograph internal tissues in real-time. An ultrasound allows a veterinarian to see into a dog's body allowing for easy viewing of organs from different angles that are not easily achieved through x-rays. The functioning of various organs and blood flow can be observed to determine if they are malfunctioning.

A dog ultrasound procedure usually proceeds as follows:

  • A dog ultrasound technician gently presses a small probe against the dog's body that emits digital sound waves
  • The sound waves are directed to various parts of the dog's abdominal area by manually shifting the probe's position
  • The sound beam changes velocity while passing through varying body tissue density, which causes echoes
  • Our ultrasound equipment converts these echoes into electrical impulses that are then further transformed into a digital image that represents the appearance of the tissues
  • These images can be viewed in real-time by a veterinarian, as well as stored for further review at any time

In modern scanning systems like the ones Carson Animal Hospital has on-site and uses on our canine patients, the sound beam sweeps through the body many times per second. This produces a dynamic, real-time image that changes as the dog ultrasound device moves across a dog's body. We can use the results of an ultrasound to determine what is ailing your dog, and to devise the most effective treatment protocol.

Common symptoms that may cause a veterinary to use ultrasound include: vomiting, weight loss, kidney impairment or blockage and heart disease.

MRI (Referred out)

Magnetic resonance imaging, or MRI, is the newest form of diagnostic imaging being used for both human and veterinary medicine. Dog MRI equipment generates a very powerful magnetic field, resulting in detailed anatomic images of whatever part of a dog's body is being scanned. No x-rays are involved, and a dog MRI is considered extremely safe.

A dog MRI procedure usually proceeds as follows:

  • Dogs must be sedated for this procedure because they cannot be restrained by humans and must remain still during the procedure
  • For the procedure, a dog is placed in a tubular electromagnetic chamber
  • The dog's body is continuously pulsed with radio waves for a period of time, usually 10-20 minutes
  • The pulsing causes the dog's body tissues to emit radio frequency waves that can be detected by the MRI equipment. Many repetitions of these pulses and subsequent emissions are required in order to generate adequate digital feedback for the equipment to interpret
  • The feedback is then converted into images that can be displayed on a screen, and can also be saved for future study

A dog MRI is not used as regularly as an x-ray or ultrasound because the equipment is very expensive, very large, and requires specially trained technicians to operate. At Carson Animal Hospital we do not currently offer comprehensive dog MRI services, we do however refer our patients to LSU for MRIs. 

CT Scans (Referred Out)

CT scans for dogs, also known as 'cat scans', are computer-enhanced dog x-ray procedures most often used to evaluate complex parts of the body, such as the head, chest, some joints and various internal organs. CT scans show different levels of tissue density, and produce more detailed images than x-rays. Unlike MRI's, CT scans for dogs do not use magnetic field waves so they cannot compare changes in fluid levels due to inflammation or bleeding. Therefore, CT scans for dogs are used in situations where an MRI is considered unnecessary but a traditional x-ray is inconclusive or insufficient.

CT scans for dogs usually proceed as follows:

  • Dogs must be sedated for this procedure because they cannot be restrained by humans and must remain still during the procedure
  • The dog is placed on a motorized bed inside of a CT scanner, a machine that takes a series of x-rays from various angles*
  • When one series, or scan, is completed, the bed moves forward, and another scan is taken
  • A computer uses these scans to create cross-sectional images of the body part under investigation, and then display the images on a monitor (An x-ray dye may be injected intravenously to make it easier to see abnormalities)
  • By sequentially scanning an entire body area, an organ or other structure can be imaged without invasively penetrating the body, or disrupting neighboring structures

CT scans for dogs are most often used by our veterinarians to detect structural changes deep within a dog's body, including:

  • Tumors
  • Deep abscesses or foreign body presence
  • Fractures

Just like MRI equipment, CT scan equipment is very expensive, large and requires trained technicians to operate, we do not currently offer CT scans at Carson Animal Hospital and will instead refer your dog to LSU.

How Canine Radiographs Influence Veterinary Recommendations

The goal of canine radiographs is to ascertain a diagnosis, or obtain a final answer without having to perform further, more invasive tests or procedures. For example, an x-ray might show some soft tissue swelling in the knee but the addition of an MRI would reveal the specific tendon or ligament tear that is causing a dog to limp and allow for a more specific treatment plan, diagnosis and prognosis.

Veterinary diagnostic imaging offers an array of incredibly useful tools within a veterinarian's toolkit. Sometimes a diagnostic imaging session can lead to the need for further diagnostics. This is why it is important to understand that diagnostic imaging may lead to a progressive fact-finding mission that must occur in order to diagnose your dog's ailment.

If you are concerned that your dog might be injured or experiencing internal problems, or to discuss how canine radiographs can benefit him or her, please contact us to schedule an appointment with one of our veterinarians today.