A 5-year-old male neutered Whippet. Initially seen with acute onset vomiting, diarrhoea, bloated abdomen, dyspnoea and grunting on expiration. Maropitant and buprenorphine was administered which resulted in the cessation of vomiting but no improvement in his breathing. There was no history of access to toxins or trauma. Repeat examination a few hours later showed heart rate 150 bpm, panting, temperature 38.8, dehydrated, mucous membrane colour pink, and CRT<2s. Severe subcutaneous emphysema was now present predominantly over the ventral and right thorax, extending to both flanks and inguinal areas.
Bloods were taken:
TP 44 (26-40)
Slightly elevated: ALT, ALP, glucose, albumin, cholesterol.
All others results were within normal limits.
Radiographs were taken under light sedation (scroll down to view)
There is a moderate amount of subcutaneous emphysema in the thorax, more evident on the right side.
On the VD there is gas in the left caudal aspect of the thorax causing retraction on the left caudal lung lobe from the thoracic wall. There is elevation of the heart from the sternum on the lateral view. These changes indicate a mild pneumothorax.
There is a moderate dilation of the dorsal mediastinum with decreased opacity (gas) highlighting the aorta, azygos vein, oesophagus, cranial vena cava and brachiocephalic artery. Part of this gas is extending cranially into the deep fascial planes of the neck and caudally into the retroperitoneum.
The cardiac silhouette is normal.
There is a diffuse interstitial pattern throughout the lung fields. Patchy increased opacity is also noted over the lungs but this might be due to the superimposed subcutaneous changes.
The retroperitoneal space is enlarged and has an overall decreased opacity, indicating the presence of gas.
A distended intestinal loop in the cranial abdomen might represent part of the colon.
The visible small intestinal loops have a normal size.
The visible portion of the liver and kidneys is normal.
1.Pneumomediastinum (green arrows) and small pneumothorax (red arrows).
2. Pneumoretroperitoneum (between green arrows)
1. Severe pneumomediastinum and pneumoretroperitoneum.
2. Mild pneumothorax. This might be secondary to the pneumomediastinum.
3. Moderate subcutaneous emphysema.
4. Emphysema in the deep fascial planes of the neck.
The possible causes of the pneumomediastinum are laceration of the pharynx/ larynx, rupture of the trachea or main stem bronchi, laceration of the oesophagus, deep lesion in the pulmonary parenchyma communicating or a penetrating injury in the neck. The severity of the findings indicates that there is a continuous leakage of gas, therefore a laceration of the upper airways might be considered more likely. Given the history a laceration caused by a foreign body could be considered. An oral examination is recommended. Endoscopy could be considered if clinically indicated.
The pneumomediastinum has already resulted in a small pneumothorax and if this progresses it may be potentially life threatening.
The dog was referred for CT and endoscopy. Conscious radiographs on arrival at the referral centre revealed a slight reduction in the amount of air in the mediastinum. A CT confirmed the findings of the pneumothorax, pneumomediastinum and pneumoretroperitoneum, but did not establish the primary cause. A tracheoscopy and oesphagoscopy also failed to identify any lesions. 300ml of air was drained from the right hemithorax, and 180mls of air from the left hemithorax. He recovered well from the anaesthetic and continued to improve over the next few days. He was discharged on amoxicillin / clavulanic acid and has since made a full recovery. The cause of the pathology remains a mystery.