Case reveal » Veterinary Diagnostic Imaging » College of Veterinary Medicine

Radiographs:

Within the soft tissues in the caudoventral cervical region, a well-defined, smoothly marginated, rectangular, and radiolucent foreign body surrounded by gas is identified (yellow arrowheads). A moderate amount of gas is present within the soft tissues and deep fascial planes in this area, as well as surrounding the cervical trachea

Ventrally distributed within the thoracic cavity, a moderate homogeneous increase in soft tissue opacity (red asterisk) border effaces the lungs, diaphragm, and cardiac silhouette.
The trachea is mildly dorsally deviated.
Within the ventral periphery of the caudal ventral lung lobes there is an alveolar pulmonary pattern with associated air bronchograms (green arrowheads).

The included skeletal structures are within normal limits, and there is no evidence of pneumomediastinum or pneumothorax.

Caudoventral cervical perforating foreign body with associated moderate, regional subcutaneous and deep fascial emphysema, consistent with the reported penetrating trauma (hidden information: impaled with a piece of wood).
Esophageal or tracheal rupture is unlikely but cannot be completely ruled out.
Mediastinal and/or pleural effusion (e.g. hemorrhage)
Moderate ventrally distributed alveolar pattern, possibly representing atelectasis; however, pulmonary contusions are also possible.

Ultrasound exam confirmed the presence of fluid within the pleural space – from ICS 3-8. The fluid was echogenic and swirling, consistent with hemorrhage. Non-aerated, including partially collapsed, lung was also observed. No pericardial effusion was seen

The wood piece was manually removed from the body via a standing operation. Splinters that remained were removed; however, due to length limitations, it is possible that not all splinters could be removed. The patient was discharged and no additional follow-up information is available.

Penetrating injuries involving wooden foreign bodies are a frequent cause of chronic wounds, draining tracts, and lameness in horses. Wood is associated with the highest rate of complications, including persistent infection and delayed healing. Accurate diagnosis is essential because wood provides an ideal substrate for bacterial colonization and biofilm formation, making antimicrobial therapy alone ineffective until the foreign material is removed.

When the foreign body is not externally visible, imaging becomes critical for localization and surgical planning. Common modalities include radiography, ultrasonography, computed tomography (CT), and magnetic resonance imaging (MRI). Among these, radiography is often the first-line technique due to its availability and cost-effectiveness. However, its diagnostic performance for wooden foreign bodies is limited.

Wooden foreign bodies are typically radiolucent, which explains why plain radiographs may fail to detect them, especially if small in size. In a large equine series, radiography identified metallic foreign bodies reliably but detected none of the wooden fragments, even when contrast fistulography was employed in some cases (Farr et al., 2010). Occasionally, secondary changes such as soft tissue swelling, gas opacity, or subtle bone lysis may suggest penetration, but these findings are nonspecific. Contrast studies can reveal filling defects within draining tracts, improving suspicion but not guaranteeing visualization of wood.
Radiographic sensitivity is further reduced by foreign body location. Structures in the proximal limb or axial skeleton are difficult to image adequately, and superimposition of bone obscures soft-tissue detail. In the foot, the hoof capsule adds complexity; even advanced digital radiography struggles to differentiate wood from adjacent soft tissues. Experimental work confirms that dry and soaked wood have radiodensities similar to soft tissue, rendering them invisible on standard projections (Ogden et al., 2020).

Although radiographs are often unrewarding, other modalities provide clues. On CT, wood appears as a linear or cylindrical structure with attenuation values that vary over time: initially low (similar to air) when dry, then increasing as the wood absorbs fluid. MRI typically shows wood as a hypointense or signal void structure on all sequences, sometimes mimicking tendons. Ultrasonography, when feasible, is highly sensitive, revealing wood as a hyperechoic linear structure with marked acoustic shadowing. However, in the foot, sonographic access is limited by the hoof capsule.

The inability of radiography to detect wooden foreign bodies means that negative radiographs do not rule out their presence. Persistent draining tracts or unexplained lameness should prompt further imaging. CT is currently the most accurate modality for detecting wood within the hoof, outperforming MRI and radiography; however, radiography and ultrasonography remain the best option for soft tissue locations in the proximal limb or thorax/abdomen.

Farr, Amanda C., et al. “Wooden, metallic, hair, bone, and plant foreign bodies in horses: 37 cases (1990-2005).” Journal of the American Veterinary Medical Association 237.10 (2010): 1173-1179.
Ogden, Nadine KE, et al. “CT more accurately detects foreign bodies within the equine foot than MRI or digital radiography.” Veterinary Radiology & Ultrasound 62.2 (2021): 225-235.
Peterson, Jeffrey J., Laura W. Bancroft, and Mark J. Kransdorf. “Wooden foreign bodies: imaging appearance.” American Journal of Roentgenology 178.3 (2002): 557-562.
Trostle, Steven S., Marcos Antonio Poddis Dos Santos, and Paul R. Stephens. “Penetrating wood foreign bodies (stob) of the coronary band in horses: 15 cases.” Journal of the American Veterinary Medical Association 262.8 (2024): 1099-1103.