How Is An X-Ray Performed On A Dog?

Introduction

X-rays are a type of imaging technique that utilizes electromagnetic radiation to create images of internal structures. In veterinary medicine, x-rays are an important diagnostic tool to examine a dog’s skeletal structure and internal organs, helping veterinarians detect signs of injury, disease, or abnormality.[1]

Some of the common reasons a veterinarian may recommend an x-ray for a dog include: diagnosing fractures and joint issues; evaluating the chest for signs of pneumonia or cancer; detecting heart problems; identifying tumors or foreign objects in the abdominal area; or monitoring arthritis and joint disease progression. The images produced from the x-ray allow the vet to have a visible picture of what is occurring inside the dog’s body.

[1] https://petkeen.com/how-much-does-dog-x-ray-cost/

Preparing for the X-Ray

There are some requirements to prepare a dog for an x-ray exam. The main requirement is fasting, where food is withheld starting the night before the x-ray. This ensures the digestive tract is empty and provides clearer images. Sedation may also be required, especially for anxious or energetic dogs who can’t hold still during the exam. This will keep the dog calm and prevent motion blur on the images. According to Veterinary Specialists of North Texas, sedation allows for better positioning and higher quality radiographs.

a vet technician preparing a dog for an x-ray exam.

In terms of preparation, the fur around the area being x-rayed may need to be shaved. This prevents obstruction or fuzziness on the images. Owners should inform the veterinarian of any medications or health conditions prior to sedation or the procedure. It’s also recommended owners bring prior x-rays for comparison if available (South Wilton Vet).

Positioning the Dog

Proper positioning is crucial for obtaining high-quality diagnostic x-ray images. The positioning will vary depending on the area being imaged. Here are some key tips for positioning dogs for common x-ray views:

For chest x-rays, the dog should be placed in sternal recumbency with the front legs pulled forward and hindlegs extended backward. This allows for better visualization of the thoracic cavity. Some vets use Velcro straps gently wrapped around the dog’s front and back legs to keep them in position (Radiography Positioning Guide).

For abdominal x-rays, the dog is placed in dorsal recumbency (on their back). The rear legs are pulled caudally and the front legs are extended cranially. Mild rotation of up to 20 degrees left or right may allow better visualization of organs. Gentle restraint helps keep dogs still (Radiographic Positioning for Dogs).

To x-ray the cervical or neck region, the neck is gently extended and head lifted. For the lumbar spine, the dog is placed in lateral recumbency with rear legs pulled forward and neck extended. Legs should be parallel but not overlapping. The beam is angled perpendicular to the spine.

For the skull, chin-lift positioning is used. The dog’s mouth is held closed and head gently lifted upward. Oblique views may require tilting the head left or right. Restraint devices help stabilize the head.

Regardless of the view, proper positioning is key for reducing motion blur and superimposition of bones/organs. This results in higher quality diagnostic images.

positioning a dog on its back for an abdominal x-ray.

Safety Precautions

When performing x-rays on dogs, it’s important to take safety precautions to protect the dog and staff from unnecessary radiation exposure. According to the American Veterinary Medical Association, the radiation dosage using modern radiology equipment is very low and does not pose significant risks.

However, best practices dictate taking reasonable precautions such as:

  • Using lead aprons and thyroid shields to cover parts of the dog’s body not being imaged.
  • Having staff wear lead aprons and stay behind protective barriers during the x-ray.
  • Using the lowest radiation dose needed for diagnostically acceptable images.
  • Taking the minimum number of exposures needed.
  • Using digital radiology systems that require lower doses than film.
  • Having pregnant staff avoid the x-ray room or wear a fetal monitoring dosimeter.

With proper safety measures, the risk of harmful radiation exposure during canine x-rays is very low. However, it’s still important for vets to follow best practices and not take unnecessary risks with radiation.

Taking the Images

The actual x-ray imaging process involves using an x-ray machine to generate x-rays that pass through the dog’s body and strike an image receptor or detector. This results in the formation of the radiograph or x-ray image.

There are two main types of image receptors used – traditional x-ray film that requires chemical processing, or advanced digital detectors that generate the image digitally. Many modern veterinary clinics use digital x-ray machines as they provide instant viewing of images without film development. The digital images can also be enhanced, duplicated easily, and stored electronically in the patient’s records.

To take the x-ray, the vet or technician operates the x-ray device while the dog remains still in position. They set the required exposure factors and activate the x-ray beam using a switch or remote control. The positioning of the image receptor depends on the area being examined. The beam is collimated or restricted to only expose the body part of interest.

The x-ray technician may wear a lead apron and thyroid shield for protection from scattered radiation. There are also radiation safety protocols in place to protect staff and ensure proper and safe operation of the x-ray equipment (James et al. 2019).

Special Views

taking an oblique view x-ray of a dog's abdomen.

Sometimes vets need to take x-rays from unique angles or positions to get a clear view of specific injuries or issues in a dog. Common special views include:

Oblique view: This is taken at an angle, usually 45 degrees between a lateral and ventrodorsal/dorsal projection. It provides more detail of organs like the spleen, liver, kidneys and urinary bladder than a standard lateral or VD/DV view (Source).

Skyline view: The dog is positioned upright with the underside and limbs facing the plate to highlight the patella and thigh region. This helps evaluate knee and patellar problems (Source).

Stress views: Specific joint manipulation prior to exposure highlights instability or laxity. For example, a craniocaudal elbow projection while flexing and extending the joint.

Contrast studies: Barium sulfate suspension given orally or rectally outlines organs like the esophagus, stomach and intestines.

Contrast Studies

Contrast media may be used during x-rays to enhance the visibility of organs, blood vessels, or tissues of interest. Contrast media contains a substance that is more radiopaque (absorbs more x-rays) than the surrounding tissue, causing those areas to appear whiter on the radiograph.

There are two main types of contrast media:

  • Positive contrast media contains barium or iodine compounds that show up white on x-rays. Barium is commonly used in GI studies.
  • Negative contrast media contains air or carbon dioxide that shows up black on x-rays. This can outline structures more clearly.

Contrast media can be given orally, injected into a body cavity, or injected intravenously. The type, amount, and method of administration depends on the area being studied. For example, barium sulfate suspension may be given orally for imaging the esophagus, while iodinated contrast agents are injected intravenously for enhanced views of the kidneys.

Potential side effects include constipation, vomiting, diarrhea, and allergic reactions. The veterinarian determines if the benefits outweigh the risks for each patient.

Contrast radiography provides important diagnostic information about the function and patency of many organ systems. When combined with standard radiography, contrast media enhances the visualization of internal structures that are otherwise difficult to evaluate.

Source: https://www.vin.com/proceedings/Proceedings.plx?CID=WSAVA2002&PID=2606

Fluoroscopy

Fluoroscopy is a type of x-ray imaging that allows real-time visualization of internal structures. This technique uses a fluoroscope, which is an x-ray emitter and fluorescent screen viewer connected to a closed-circuit TV system. The dog is positioned on the table and the x-ray beam is passed through the body part being examined. The fluoroscope converts the x-rays into a visible light image that shows on the screen. This allows the veterinarian to see motion within the body in real-time.

Fluoroscopy is useful for evaluating dynamic processes like swallowing, joint motion, or cardiac function. It can also guide minimally invasive procedures like stent placement or Contrast fluoroscopy enhances the visibility of blood vessels, the gastrointestinal tract, or the urinary system by using a contrast agent that shows up brightly on x-rays. For example, barium sulfate can outline the esophagus and stomach.

Fluoroscopy provides valuable real-time visualization but requires longer radiation exposure than standard radiography. The veterinarian takes precautions to limit the radiation dose and only uses fluoroscopy when clinically warranted (source).

CT Scans

Computed tomography (CT) scans use a series of X-ray views taken from different angles to generate cross-sectional images (“slices”) of the bones and soft tissues inside the dog’s body. It provides more detailed images than conventional X-rays.

CT scans are useful for obtaining high-resolution 3D images of complex body structures like the skull, spine, joints, chest, and abdomen. They allow veterinarians to clearly see abnormalities that may not show up well on regular X-rays, such as tumors, fractures, foreign bodies, organ disease, and fluid accumulations.

a vet reviewing ct scan images of a dog on a computer.

The CT scanner is a large doughnut-shaped machine. The dog lies on a motorized table that moves through the scanner, while an X-ray tube rotates around the body. Multiple X-ray detectors on the opposite side of the ring detect the radiation and convert it into digital data that a computer uses to construct cross-sectional images.

CT scans require the dog to lie still, often with the assistance of sedation or anesthesia. Contrast agents may be administered intravenously or swallowed to enhance visualization of the digestive tract. Radiologists analyze the series of CT images on a computer to diagnose and characterize any abnormalities.

CT technology has advanced considerably in veterinary medicine, allowing for faster scan times and more detailed 3D reconstructions. It is an important diagnostic imaging tool, but the relatively high costs and need for anesthesia limit its routine use compared to basic X-rays.

After the X-Ray

After the x-rays have been taken, the veterinarian will need to interpret the images to make a diagnosis. This requires training and experience in radiology to identify abnormalities and understand their significance. The vet will look for issues like bone fractures, arthritis, foreign bodies, masses or tumors, pneumonia, and more. They may also compare the images to previous x-rays of the dog to determine if there are any changes.

Once the radiologist has analyzed the x-rays, they will provide a report of their findings and recommended next steps to the referring veterinarian. This may include further diagnostic testing, initiating or altering treatment plans, or recommendations for specialist referrals or surgery. The original vet will then discuss the results and recommendations with the dog’s owner to determine the best course of action for care of their pet.

It’s important for vets to carefully analyze, interpret and report on x-rays. Their expert analysis guides treatment decisions and helps provide the best possible care for the animal patient. After the imaging process, clear communication with the owner and follow-up action is key.

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