History
A 2-year-old 14-kg spayed female English Bulldog was referred to University of Wisconsin Veterinary Care because of a 2-day history of progressively labored breathing, lethargy, and pyrexia after an incident of vomiting. A week prior to referral, the dog was evaluated for productive coughing and gagging, which resolved with oral administration of azithromycin (15 mg/kg, PO, q 24 h). On physical examination, the dog was pyrexic (40.6 °C; reference range, 37.9 to 39.9 °C), tachypneic (60 breaths/min; reference range, 15 to 30 breaths/min), and dyspneic with increased respiratory effort. The dog had a heart rate of 130 beats/min (reference range, 70 to 120 beats/min) and pink mucous membranes. Tracheal sounds reflected to the right hemithorax, and increased lung sounds were auscultated over the left hemithorax.
A CBC revealed 7.5 × 103 WBCs/µL (reference range, 5.0 × 103 to 14.0 × 103 WBCs/µL), with a mildly high band neutrophil count (0.4 × 103 band neutrophils/µL; reference limit, ≤ 0.2 × 103 band neutrophils/µL), mild lymphopenia (0.4 × 103 lymphocytes/µL; reference range, 0.7 × 103 to 4.3 × 103 lymphocytes/µL), and mild thrombocytosis (520 × 103 platelets/µL; reference range, 175 × 103 to 500 × 103 platelets/µL). Results of serum biochemical analyses indicated mildly low total calcium concentration (8.9 mg/dL; reference range, 9.7 to 12.3 mg/dL) and mildly high alkaline phosphatase activity (169 U/L; reference range, 20 to 157 U/L). Results of venous blood gas analyses confirmed hypoxemia, with a partial pressure of oxygen of 40.8 mm Hg (reference range, 45 to 65 mm Hg).
The dog received butorphanol (0.2 mg/kg/h, IV constant rate infusion) for sedation and was placed in an oxygen cage (60% Fio2): however, the dog’s condition deteriorated, with continued tachypnea and dyspnea. Thus, the dog underwent general anesthesia, intubation, and mechanical ventilation. Orthogonal thoracic radiography was performed (Figure 1).
Left lateral (A), right lateral (B), and dorsoventral (C) thoracic radiographic images of an anesthetized 2-year-old spayed female French Bulldog evaluated because of a 2-day history of labored breathing, lethargy, and pyrexia after vomiting that progressed to dyspnea requiring mechanical ventilation.
Citation: Journal of the American Veterinary Medical Association 260, 1; 10.2460/javma.19.11.0590
Formulate differential diagnoses, then continue reading.
Diagnostic Imaging Interpretation and Findings
Thoracic radiography revealed a severe alveolar pattern with well-defined air bronchograms in the ventral aspects of all lung lobes (Figure 2). Within the caudodorsal aspect of the right hemithorax was a large, ovoid gas opaque structure with no pulmonary markings throughout. Many small, round gas foci were superimposed with the right caudal lung lobe adjacent to this gas-filled structure. In the region of the accessory lung lobe and diaphragmatic margin was a large, rounded soft tissue opacity with ill-defined margins. A moderate amount of soft tissue opaque material was in the pleural space ventrally and bilaterally, with pleural fissure lines and mild retraction of the pulmonary margins from the thoracic wall evident.
Same radiographic image as Figure 1. An alveolar pattern (white arrows) is evident in the ventral aspect of all lung lobes. An ovoid, gas opaque structure (asterisks) is in the region of the dorsal aspect of the right caudal lung lobe, and there are multiple small round gas foci ventrally. A large ill-defined soft tissue opacity (black arrowheads) is in the region of the accessory lung lobe and causes border effacement of the diaphragm.
Citation: Journal of the American Veterinary Medical Association 260, 1; 10.2460/javma.19.11.0590
The diagnostic interpretation was severe multifocal pneumonia, moderate pleural effusion, and cavitated right caudal lung lobe mass with pulmonary emphysema, pneumothorax, or both. Differential diagnoses included ruptured pulmonary abscess or granuloma secondary to infectious bronchopneumonia or inhaled foreign body, congenital lobar emphysema, or, less likely, lung lobe torsion with abscess formation and rupture. A mass effect in the caudal aspect of the thorax was thought to have been caused by accessory lung lobe consolidation secondary to bronchopneumonia, abscess formation, or diaphragmatic hernia.
Thoracocentesis was performed, and results of cytologic examination of thoracic fluid indicated an exudate with mixed bacterial infection and marked neutrophilic and macrophagic inflammation, consistent with pyothorax. A thoracostomy tube and nasogastric tube were placed, and thoracic CT was performed. On CT, a large, ovoid gas-attenuating structure with a moderate amount of fluid ventrally and a well-defined gas-fluid interface was identified in the right caudodorsal pleural space, consistent with an abscess (Figure 3). Within the pleural space ventrally and bilaterally was a large amount of fluid and many small, round gas foci, indicative of pleural effusion and pneumothorax. Protruding through the esophageal hiatus into the caudal thoracic cavity was a large, encapsulated hernial sac that contained displaced spleen, mesentery, and mesenteric lymph nodes. The spleen was folded on itself and contained a sharply demarcated, non–contrast-enhancing region. The right caudal lung lobe had an alveolar pattern and was not decreased in volume, whereas the right middle and accessory lung lobes were collapsed.
Postcontrast transverse (A), sagittal (B), and dorsal (C) plane thoracic CT images of the dog described in Figure 1 imaged in ventral recumbency. A large, encapsulated hernial sac (white arrows) is in the caudodorsal region of the thoracic cavity and surrounds the caudal portion of the esophagus (Eo). This hernial sac contains displaced mesentery, enlarged and rounded mesenteric lymph nodes (LN), and spleen (Sp). The spleen is folded on itself and contains a large and sharply demarcated non–contrast-enhancing region. There is ventral deviation of the caudal vena cava (CVC) and cranial displacement of the heart (black asterisk). In the caudodorsal pleural space of the right hemithorax, a thick-walled structure (white asterisks) contains a linear gas-fluid interface and small, round, gas-attenuating foci within the fluid-filled portion ventral to this interface, consistent with a pleural abscess. A large amount of non–contrast-enhancing fluid (Eff) is in the ventral aspect of the pleural space adjacent to the hernial sac and pleural abscess, and a small amount of gas (black arrow) is in the pleural space adjacent to the abscess, consistent with pneumothorax. The mineral-attenuating nasogastric tube (white arrowhead) and thoracostomy tube (black arrowheads) are in the esophagus and right pleural space, respectively. Dashed lines in the inset images represent the plane of the respective multiplanar reconstructed images (B and C). T11 = Eleventh thoracic vertebra.
Citation: Journal of the American Veterinary Medical Association 260, 1; 10.2460/javma.19.11.0590
Findings on CT confirmed right pleural abscess, pleural effusion, pneumothorax, and hiatal herniation of abdominal organs. Herniation of spleen, mesentery, and mesenteric lymph nodes was suspected to have been into the cavum mediastini serosum, the potential space between 2 mediastinal pleural leaves also known as Sussdorf space.1 Altered splenic blood flow was thought to have been secondary to ischemia or thrombosis from hernial entrapment. The pulmonary changes were likely secondary to severe pulmonary atelectasis, with an alternative differential diagnosis of pneumonia.
Treatment and Outcome
The dog underwent ventral midline laparotomy and median sternotomy. A discrete abscess was identified in the pleural space of the right hemithorax and adhered to the adjacent lung lobes. Hiatal herniation of the spleen, mesentery, and mesenteric lymph nodes through the esophageal hiatus was confirmed. The spleen was folded on itself and congested secondary to compromised vascular supply. Abdominal contents were reduced into the abdominal cavity, and a splenectomy, hiatal herniorrhaphy, esophagopexy, and gastropexy were performed. A portion of the pleural abscess wall was removed, and the incompletely excised remnant was lavaged. The thoracostomy tube was replaced. The dog recovered uneventfully from anesthesia and was weaned off of supplemental oxygen within 12 hours after surgery.
Bacterial culture performed on swab samples obtained from the pleural abscess yielded heavy growths of β-hemolytic Staphylococcus spp and Staphylococcus pseudintermedius. Histologic examination of the pleural abscess revealed an intralesional foreign body suggestive of plant foreign material. The dog was treated with chloramphenicol (53 mg/kg, PO, q 8 h, for 14 days), enrofloxacin (10 mg/kg, PO, q 24 h, for 7 days), and fluconazole (5 mg/kg, PO, q 12 h, for 30 days) for broad-spectrum antibacterial and antifungal coverage. Two weeks after admission, the dog was discharged.
Comments
Pyothorax is an uncommon condition in dogs, and a specific etiology is often not identified. Foreign body migration, penetrating or blunt thoracic trauma, esophageal perforation, parapneumonic spread, previous thoracocentesis, neoplasia, and ruptured lung abscesses have been reported as causes in dogs and cats.2 In a clinical review of pyothorax in dogs and cats, a cause was identified in up to 22% (10/46) of cases, with migrating plant material reported as the most commonly documented etiology.2
Hiatal hernias (HHs) are common in chondrodystrophic dogs, and bulldogs are overrepresented.3 Hiatal hernia is defined as the protrusion of abdominal contents into the thoracic cavity through the esophageal hiatus that may be congenital or acquired.4 Further, HHs are hypothesized to be secondary to long-term negative intrathoracic pressure observed in brachycephalic dogs and have been shown to occur secondary to respiratory disease.4,5 We surmised that the dog of the present report had inhaled a plant foreign body that migrated and resulted in a pleural abscess and that a congenital HH was exacerbated by the patient’s respiratory distress and increased intrathoracic pressure. Concomitant brachycephalic airway syndrome contributed to the dog’s dyspnea and predisposed it to type IV4 HH.
Thoracic radiography alone did not allow for definitive diagnoses of pleural abscess and HH in the dog of the present report because of superimposition of soft tissue structures. In humans, contrast‐enhanced CT is used to differentiate pyothorax from lung abscess with nearly 100% accuracy.2 In our case, findings on contrast-enhanced CT were used to determine the site of the abscess, revealed the extent of pleural and pulmonary disease, and identified HH with herniation of abdominal contents. It also provided information on splenic perfusion and allowed for accurate surgical planning in this complex case.
Acknowledgments
The authors declare that there were no financial or other conflicts of interest.
References
- 1. ↑
Baines E. The mediastinum. In: Schwarz T, Johnson V, eds. BSAVA Manual of Canine and Feline Thoracic Imaging. British Small Animal Veterinary Association; 2008:177–199.
- 2. ↑
Stillion JR, Letendre JA. A clinical review of the pathophysiology, diagnosis, and treatment of pyothorax in dogs and cats. J Vet Emerg Crit Care (San Antonio). 2015;25(1):113–129.
- 3. ↑
Reeve EJ, Sutton D, Friend EJ, Warren-Smith CMR. Documenting the prevalence of hiatal hernia and oesophageal abnormalities in brachycephalic dogs using fluoroscopy. J Small Anim Pract. 2017;58(12):703–708.
- 4. ↑
Sivacolundhu RK, Read RA, Marchevsky AM. Hiatal hernia controversies—a review of pathophysiology and treatment options. Aust Vet J. 2002;80(1–2):48–53.
- 5. ↑
Poncet CM, Dupre GP, Freiche VG, Estrada MM, Poubanne YA, Bouvy BM. Prevalence of gastrointestinal tract lesions in 73 brachycephalic dogs with upper respiratory syndrome. J Small Anim Pract. 2005;46(6):273–279.
