Radiograph (X-ray)
A diagnostic imaging technique using X-rays to create two-dimensional images of internal structures. Used to evaluate bones, chest, abdomen, and joints in dogs.
A radiograph (commonly called an X-ray) is a two-dimensional diagnostic image created by passing X-ray beams through the body. Different tissues absorb radiation at different rates — bone appears white, air appears black, and soft tissues appear in shades of gray. Radiography is the most widely used and accessible diagnostic imaging modality in veterinary medicine.
What Radiographs Show Well
Radiographs excel at evaluating structures with high contrast differences:
- Bone: fractures, bone tumors (osteosarcoma), degenerative changes, growth plate abnormalities
- Joints: hip dysplasia scoring (OFA evaluation), elbow dysplasia, arthritis severity grading
- Chest: heart size and shape, lung patterns (pneumonia, metastatic disease, edema), tracheal collapse
- Abdomen: organ size and shape, foreign body detection, bloat/GDV diagnosis, bladder stones
- Teeth: dental radiographs reveal root disease invisible on oral exam — approximately 60% of dental pathology is below the gumline
Limitations
Radiographs have notable blind spots:
- Soft tissue detail: limited ability to distinguish between soft tissue organs of similar density. Ultrasound is superior for evaluating internal organ architecture.
- Two-dimensional: structures overlap. Most studies require at least two views (typically lateral and ventrodorsal) to localize lesions in three-dimensional space.
- Early disease: radiographic changes in conditions like arthritis lag behind clinical signs. A dog may be painful before bony changes appear on film.
- Spinal cord: radiographs show vertebral bone but cannot directly visualize the spinal cord or disc material. MRI is required for IVDD diagnosis.
Common Clinical Applications
Hip and Joint Screening
OFA hip and elbow evaluations use standardized radiographic positioning to grade joint conformation. The PennHIP method uses distraction radiographs to measure joint laxity. These screenings are critical for breed-specific joint screening protocols.
Thoracic (Chest) Radiographs
Three-view thoracic radiographs are standard for:
- Cardiac silhouette evaluation (before echocardiogram)
- Staging cancer (detecting lung metastasis)
- Evaluating cough, labored breathing, or exercise intolerance
- Pre-anesthetic screening in senior dogs
Abdominal Radiographs
Used to evaluate organ size, detect foreign bodies, identify bladder stones, and diagnose gastric dilatation-volvulus (GDV) — the classic “double bubble” sign on radiograph is diagnostic.
Sedation Requirements
Most diagnostic radiographs require the dog to remain still in a specific position. Mild sedation may be needed for painful dogs or precise positioning (hip screening). The radiation exposure from veterinary radiographs is very low and poses no meaningful health risk to the patient.
Cost and Accessibility
Radiography is available at virtually all veterinary clinics, with most studies costing $150-400 depending on the number of views and body region. This accessibility makes it the first-line imaging choice for most clinical questions.