Pneumothorax is defined as abnormal accumulation of air in the pleural space and is a significant clinical problem (12,17). Within the veterinary literature, pneumothorax is well described in several animals (3,9,14,17). While not frequently reported in wild animals in Korea, particularly not in cervids, traumatic pneumothorax stands out as the most common form of pneumothorax. Closed traumatic pneumothorax often arises from blunt force (e.g., vehicular collision) (15).

A Korean water deer (Hydropotes inermis) is the most common wild animal species in Korea, and incidents of water deer roadkill are widespread across the country, occurring on national highways, regional highways, and small rural roads (5). Among 36,863 roadkill incidents that occurred on Korean highways between 2004 and 2019, Korean water deer constituted a significant majority, accounting for 28,045 (76.1%) (8). Trauma resulting from vehicular collision includes skin burns, limb fractures, articular luxation, spinal fractures, pelvic fractures, and traumatic brain injuries in water deer. In many previous studies, trauma has been described as a significant contributing cause of death in cervids (1,10,19).

This case report highlights the management of a female water deer that developed pneumothorax following a vehicular collision. Within the scope of this report, we discuss the unique challenges related to diagnosing and treating such trauma in wildlife, particularly pneumothorax.

A female water deer was rescued after being hit by a car in Heongseong-gun, Gangwon. The deer initially exhibited an inability to stand, necessitating immediate intervention. Clinical examination identified numerous injuries, including nasal bleeding, ocular congestion, and thermal neck injuries. Thoracic radiographs were obtained using the digital radiography system VXR-9M (DRGEM, Gwangmyeng 14322, Korea), which confirmed pneumothorax and fractures in the 8th-11th right ribs (Fig. 1A, B). In addition, computed tomography (CT) imaging was performed using a Somatom Emotion 6 (Siemens, Munich, Bayern, Germany), revealing a severe pneumothorax predominantly affecting the left lung (Fig. 1C). In conclusion, the water deer was found near a road with heavy traffic in a farmland area, and suffered from closed traumatic pneumothorax resulting from fractured ribs due to a vehicle collision (Fig. 2A).

Figure 1. Thoracic radiographic findings. (A) Right lateral view showing pneumothorax (white arrow) (B) Ventrodorsal view showing fracture of 8th-11th right ribs (arrowhead). (C) Computed tomographic findings: dorsal view showing pneumothorax in the water deer.

Figure 2. (A) Rescue site (farmland next to the road). (B) Water deer after recovering from pneumothorax. (C) Release of the water deer after treatment.

The water deer was stabilized through oxygen supplementation, and emergency thoracocentesis was performed following anesthesia induction with isoflurane (Ifran^®, Hana Pharm. Co. Ltd., Korea). The procedure involved a 22 G scalp vein set needle along with 20 and 50 cc syringes. Four thoracocentesis procedures were conducted over a span of 13 days, with 100 mL removed each time, resulting in the evacuation of approximately 400 mL of air. For pain management, Butorphanol tartrate (Butorphan Inj., Myungmoon Pharm Co. Ltd., Korea) at a dosage of 0.2 mg/kg was administered intravenously to the water deer for 10 days. Additionally, a solution of Dextrose 25 g/L and Sodium Chloride 4.5 g/L (Halfsol Inj., Dai Han Pharm Co. Ltd., Korea) was provided both subcutaneously and intravenously for hydration.

Serial CT scans were performed to monitor resolution of the pneumothorax. From the second scan, the water deer sedated with an intramuscular injection of 1 mg/kg xylazine HCL (Rompun^®, Bayer AG, Germany). For xylazine reversal, yohimbine HCL (Zyverse, KBNP., Korea) 0.2 mg/kg injected intravenously. The water deer’s pneumothorax showed gradual improvement until the 13th day and finally resolved completely (Fig. 3). Following thoracocentesis, spontaneous improvement in respiratory signs and voluntary enhancement of appetite were observed (Fig. 2B). Finally, the water deer was released healthy into the wild (Fig. 2C).

Figure 3. Computed tomographic dorsal (based on tracheal bifurcation) and transverse (based on 11th thoracic vertebrae) views of the thorax of the water deer. (A) Day 1: Most of the lungs except the right posterior lobe show atelectasis due to pneumothorax. (B) Day 2. (C) Day 8. (D) Day 9. (E) Day 13: Recovery of pneumothorax can be observed.

Specifically, CT has emerged as a valuable diagnostic imaging technique in animals, facilitating the identification of trauma such as fractures and thoracic pathologies (6,18). In this case, the use of CT proved instrumental in accurately identifying pneumothorax and lesion locations in water deer as well as in evaluating the efficiency of thoracic drainage after thoracocentesis. CT dorsal view in Fig. 1 was compared by referencing the tracheal bifurcation, as it was not possible to capture the image with the deer in the same posture and position each time. This approach was adopted to optimize the comparability of pneumothorax. In addition, through evaluation of pneumothorax recovery using three-dimensional surface reconstructions of CT scan, it was confirmed that the lung volume increased from 169.8 cm³ at the time of first diagnosis to 1152.0 cm³ after recovery (Fig. 4).

Figure 4. Three-dimensional surface reconstructions of the water deer’s lung in the sternal recumbent position. (A) Lung volume of day 1: 169.8 cm³. (B) Lung volume of day 13: 1152.0 cm³.

Cervids, including water deer, are susceptible to stress, and physical restraint can lead to fatal situations such as capture myopathy (2). Therefore, chemical restraint may be more effective (11). However, the use of anesthetics can result in complications such as muscle stiffness, respiratory depression, and cardiac arrest. To mitigate these risks, Xylazine hydrochloride (an alpha-2 agonist) was used during the follow-up process, except for the first CT scan in this case (7). It was administered intramuscularly at a low dose to sedate the water deer, allowing continuous monitoring of its condition and minimizing potential side effects (7,13). This approach was facilitated in part by the rapid CT scan speed, enabling the imaging of anatomical structures in just a few seconds (16).

In animals suffering from severe respiratory depression due to pneumothorax, effective thoracentesis usually results in almost immediate improvements in respiratory characteristics and oxygen saturation (18). Using ultrasound-guided procedures to treat pneumothorax can help determine the location and depth of the lesion, enabling improved visualization and guidance of the needle tip to the desired target during real-time ultrasound (4). However, given the extensive nature of the pneumothorax in this water deer case, we opted against performing ultrasound-guided procedures. Instead, we successfully treated the severe pneumothorax by accessing the affected area in the left posterior lobe through thoracocentesis.

This case report focuses on the management of closed traumatic pneumothorax resulting from rib fractures following vehicular trauma in a female water deer and the observation of gradual and spontaneous resolution through serial CT imaging. This case will help us understand and manage similar injuries in wildlife treatment and rehabilitation.

The authors have no conflicting interests.