Findings:
- Dorsal to the carina, proximally located within the body of a rib, a complete, well-defined and sharply marginated fracture with mild craniodorsal displacement is identified (highlighted in green). At the level of the fracture, multiple ill-defined and sharply margined fracture fragments are noted.
- The pleural space contains a large volume of gas resulting in rounding and retraction of the lung lobes from the thoracic body wall (pink arrows outlining the dorsal margin of the lungs). The lungs are subsequently hypoinflated and diffusely inhomogeneously increased soft tissue opacity.
- Superimposed over the caudoventral thorax and carnioventral abdomen, there is a heterogenous gas and soft tissue opacity.
- Seen on both lateral projections,superimposed over the region of the caudal vena cava, there is a well-defined and circular soft tissue opacity.
- Multiple open physes are present, consistent with the young age of the patient.
Conclusions:
- Acute rib fracture and pneumothorax. These findings are consistent with the clnical history of trauma.
- Severe subcutaneous emphysema.
- The heterogenous and circular opacities in the caudoventral thorax may be associated with external wounds and/or wound bandage material. Underlying pulmonary pathology is not ruled out.
Follow-up:
- A standing thoracostomy was performed to determine the extent of the chest trauma. A rib fragment was identified but not removed. The wound was flushed and packed with sterile sponges. A chest tube was placed, and a large amount of gas was removed from the pleural space, improving the patient’s comfort level.
- A small amount of pleural effusion was identified using ultrasound. Thoracocentesis confirmed hemorrhage.
A little bit more…
- Thoracic trauma in horses is most commonly secondary to impact with an external object (Laverty et al.). The pectoral and axillary regions are most commonly affected (Hassel et al.).
- From most to least prevalent, clinical findings may include (Laverty et al., Sprayberry et al.):
- subcutaneous emphysema
- pneumothorax
- hemothorax
- pneumomediastinum
- Comminuted fractures can result in injury to the lungs and pleural cavity, resulting in complications like pneumothorax, hemothorax, and pleuropneumonia (Hassel et al.).
- Horses have an incomplete mediastinum with small fenestrations; therefore, distribution of gas within the pleural is most often bilateral (Hassel et al.).
- Pneumomediastinum may be secondary to the presence of subcutaneous emphysema, such as secondary to an axillary wound (Hassel et al.).
- Thoracic radiographs may be considered to screen for the presence of rib fractures and pneumothorax. Additionally, radiographs may be used to quantify the severity of gas within the pleural space and assess the efficacy of centesis (Laverty et al.). In adult horses, rib fractures may be difficult to identified on thoracic radiographs due to the large body mass and radiographic exposure limits (Hassel et al.)
- A study by Partlow et al. identified two-dimensional (84%) and M-mode (80%) ultrasound to be more sensitive than radiography (48%) for pneumothorax detection.
- Ultrasound may also be a preferred modality to screen/quantify pleural effusion (Laverty et al., Sprayberry et al.). Ultrasound also has the advantage of being fast and portable, therefore most convenient for stall side exams (Sprayberry et al.).
- Nuclear scintigraphy is sensitive for the detection of rib fractures in horses (Hall et al., Dahlberg et al.). Ultrasound can identified a greater number fracture when compared to radiography following scintigraphy (Hall et al.).
- Approximately 75% of the horses have a positive outcome (Laverty et al.). Concurrent trauma to the abdomen may carry a poorer prognosis (Laverty et al., Sprayberry et al.).
References:
- Laverty, S., Lavoie, J. P., Pascoe, J. R., & Ducharme, N. (1996). Penetrating wounds of the thorax in 15 horses. Equine veterinary journal, 28(3), 220-224.
- Partlow, J., David, F., Hunt, L. M., Relave, F., Blond, L., Pinilla, M., & Lavoie, J. P. (2017). Comparison of thoracic ultrasonography and radiography for the detection of induced small volume pneumothorax in the horse. Veterinary Radiology & Ultrasound, 58(3), 354-360.
- Hassel, D. M. (2007). Thoracic trauma in horses. Veterinary Clinics of North America: Equine Practice, 23(1), 67-80.
- Sprayberry, K. A., & Barrett, E. J. (2015). Thoracic trauma in horses. Veterinary Clinics: Equine Practice, 31(1), 199-219.
- Dahlberg, J. A., Ross, M. W., Martin, B. B., Davidson, E. J., & Leitch, M. (2011). Clinical relevance of abnormal scintigraphic findings of adult equine ribs. Veterinary Radiology & Ultrasound, 52(5), 573-579.
- Hall, S., Smith, R., Ramzan, P. H., Head, M., Robinson, N., & Parker, R. (2023). Rib fractures in adult horses as a cause of poor performance; diagnosis, treatment and outcome in 73 horses. Equine Veterinary Journal, 55(1), 59-65.
