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CASE REPORT
Unusual congenital pulmonary anomaly with presumed left lung hypoplasia in a young dog C. M. Lee*, J. H. Kim†, M. H. Kang*, K. D. Eom† and H. M. Park* *Department of Veterinary Internal Medicine, College of Veterinary Medicine, Konkuk University, Seoul 143-701, South Korea †Department of Veterinary Radiology and Diagnostic Imaging, College of Veterinary Medicine, Konkuk University, Seoul 143-701, South Korea
A seven-month-old, entire, male miniature schnauzer dog was referred with acute vomiting, inappetence and depression primarily as a result of a gastric foreign body (pine cones). During investigations, thoracic radiographs revealed increased volume of the right lung lobes, deviated cardiomediastinal structures and elevation of the heart from the sternum. Thoracic computed tomography revealed left cranial lung lobe hypoplasia and extension of the right cranial lung parenchyma across the midline to the left hemithorax. Branches of the right pulmonary vessels and bronchi also crossed the midline and extended to the left caudal lung lobe. These findings suggested that the right and left lungs were fused. In humans this finding is consistent with horseshoe lung, which is an uncommon congenital malformation. To the authors’ knowledge, this case represents the first report of such a pulmonary anomaly in a dog.
Journal of Small Animal Practice (2014) 55, 274–277 DOI: 10.1111/jsap.12192 Accepted: 23 December 2013; Published online: 17 March 2014
INTRODUCTION
CASE HISTORY
Horseshoe lung is a rare congenital pulmonary anomaly in which the pulmonary parenchyma extends from the lung base across the midline and fuses with the base of the contralateral lung (Frank et al. 1986). Approximately 40 cases have been reported in humans, mostly associated with hypoplasia of the right lung, dextrarotation of the apex of the heart and abnormal drainage of the right pulmonary veins into the right atrium (Frank et al. 1986, Ersöz et al. 1992). Pulmonary hypoplasia represents a broad range of malformations characterised by incomplete development of lung tissue, and includes a spectrum of concurrent problems (e.g. hypoplasia, aplasia and agenesis of selected lung segments or all lung segments) (Currarino & Williams 1985). Early clinical signs in neonates, infants and children primarily relate to respiratory problems. The most common findings are frequent respiratory distress, recurrent pneumonia and episodes of cyanosis (Frank et al. 1986). To the authors’ knowledge, this report is the first to describe a dog that presumably had horseshoe lung with left lung hypoplasia. 274
A seven-month-old, entire, male miniature schnauzer dog was presented with acute vomiting, inappetence and depression. Physical examination findings included dehydration, abdominal pain and muffled heart sounds on the right side of the heart. Blood biochemistry analysis revealed hyponatraemia (136 mmol/L; reference interval: 141 to 152 mmol/L), hypokalaemia (2·5 mmol/L; reference interval: 3·8 to 5·0 mmol/L) and hypochloraemia (95 mmol/L; reference interval: 102 to 117 mmol/L). Other serum chemistry values, blood gas analysis and complete blood count results were within their respective reference intervals. Thoracic radiography revealed hyperlucent right lung lobes with increased volume and left-sided mediastinal shift, rotation of the apex of the heart towards the left side, elevation of the heart from the sternebrae and an asymmetrical diaphragm (Fig 1A, B). Further cardiopulmonary examinations were performed because the lung pattern was suggestive of reduced pulmonary perfusion. An electrocardiogram demonstrated left shift of the mean electrical axis, but echocardiography showed no structural or functional
Journal of Small Animal Practice
•
Vol 55
•
May 2014
•
© 2014 British Small Animal Veterinary Association
Canine horseshoe lung
FIG 1. (A) Ventrodorsal and (B) left lateral thoracic radiographs. Leftsided displacement of cardiomediastinal structures, elevation of the heart from the sternum and cranially displaced diaphragm of the left side are present. (The dog’s right side is displayed on the left.) There is increased volume of the right lung lobe (white arrows). (C) The contrastenhanced dorsal reconstruction computed tomography (CT) image shows displacement of the mediastinum, including the oesophagus. (D) The postcontrast transverse CT image shows left-sided deviation of the cardiomediastinal structures. The mediastinum is displaced and lying adjacent to the thoracic wall
abnormalities. Abdominal radiography and ultrasonography revealed a gastrointestinal foreign body. The foreign body and the course of the oesophagus in relation to the mediastinal shift were evaluated by barium contrast study. This revealed a modified oesophageal course owing to the increased volume of the right lung lobes. From the diagnostic imaging findings (increased volume of the right hemithorax and mediastinal shift), the differential diagnoses were unilateral lung collapse, pneumothorax and unilateral pulmonary emphysema with compensatory hyperinflation. To further investigate the pulmonary abnormalities, a multidetector computed tomography (CT) examination was performed under general anaesthesia. The CT parameters were 120 kVp, 200 mAs and 1·250-mm slice thickness without gantry tilting. The CT images revealed deviation of the heart with a hypoplastic left cranial lung lobe. The right lung lobes and accessory lung lobe were significantly enlarged. Because of the asymmetric lungs, the mediastinal structures (including the oesophagus and heart) were deviated to the left side. The oesophagus had an anomalous course (Fig 1C, D). Gastric foreign bodies were present. Transverse CT images with a lung window setting revealed an anomalous branch from the right bronchi and pulmonary vessels in the cranial lobe that crossed the midline to the left hemithorax (Fig 2A to D). The bronchus and pulmonary vessels in the right
FIG 2. (A to D) Contiguous transverse computed tomography (CT) images in the lung window show that the bronchi in the right cranial lung lobe cross the midline to the left hemithorax. (The dog’s right side is displayed on the left.) The white arrowhead indicates the course of the bronchi in serial CT images. (E to I) Contiguous transverse CT images in the lung window show that the bronchi cross the right caudal lobe through the accessory lobe to left hemithorax. The lobar bronchi of the accessory lobe from the right main bronchus extend to the left caudal lobe (white arrow). A, accessory lobe; Lc, left caudal lobe; Rc, right caudal lobe Journal of Small Animal Practice
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Vol 55
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May 2014
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© 2014 British Small Animal Veterinary Association
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C. M. Lee et al.
FIG 3. Contrast-enhanced computed tomography (CT) angiography of (A) the right cranial lung lobe and (B) caudal lung lobes. (The dog’s right side is displayed on the left.) On the transverse images, the right cranial and caudal pulmonary vessels pass from the right side through midline to the left side. The accessory pulmonary vessels extend to the left caudal lung lobe (white arrowhead). A, accessory lobe; Lc, left caudal lobe; Rc, right caudal lobe
caudal lung lobe crossed the midline. The lobar bronchi of the accessory lobe connected directly to the left caudal lobar bronchi (Fig 2E to I). Contrast-enhanced CT images (lung window setting) revealed that right pulmonary vessels arose from the right side and extended to the left side (Fig 3). The pulmonary artery in the accessory lung lobe extended to the left caudal lung lobe. Three-dimensional volume-rendered CT images revealed that the increased right lung volume and the right bronchi extended from the right bronchus to the left lung lobe parenchyma. Despite the radiological findings of pulmonary deformation, the chief complaint was acute vomiting associated with a gastric foreign body. The gastric foreign body required removal before the relationship between the clinical signs and the anomalous course of the oesophagus could be evaluated. The gastric foreign body was removed by gastroscopy. Endoscopic findings revealed a distorted oesophageal lumen; hyperaemic mucous membranes of the oesophagus, stomach and duodenum; and the gastric foreign body. After retrieving the foreign body (a pine cone), the dog was treated with 44 mg/kg/day ampicillin (Amcillin; Chong Kun Dang Pharmaceutical Corp.) and 10 mg/kg/day cimetidine (Cimetidine; Nelson Pharm Korea) twice a day orally to control postoperative complications such as oesophagitis and gastritis. One week after the operation, the dog had no clinical signs, but the oesophageal course remained modified. The dog was discharged without additional treatment and in good physical condition.
DISCUSSION In human medicine, horseshoe lung is a rare congenital malformation in which pulmonary tissue extends from one side of the lung and fuses with the contralateral lung (Frank et al. 1986, Ersöz et al. 1992). The airway and arterial supplies to the isthmic portion of a horseshoe lung branch from the hypoplastic lung (Goo et al. 2002, Oguz et al. 2009). 276
One study reported that normal canine thoracic radiological findings are similar to human horseshoe lung anomalies because the classic anatomical description of the dog lung includes an accessory lobe in the midline (Hawass et al. 1990). However, the description only focuses on anatomical differences between species, not on the fusion between any lung lobes. From the human perspective, an accessory lobe in the midline is not normally present because humans have a completely separated hemithorax. By contrast dogs have an accessory lobe in the midline and incomplete thoracic separation by the thin pleura. Because of these anatomical differences, the features of a canine lung anomaly suspicious for horseshoe lung may be different from that described in humans. The canine lung has no isthmic portion, which reportedly is an important feature of horseshoe lung in humans. Anatomical differences in lung arrangement in humans and dogs may explain the dissimilarity of the fused form. In the authors’ opinion, because of these features, fusion of both sides of the lungs could be formed more commonly in dogs than in humans. The most common concurrent findings in humans are hypoplasia of the right lung, dextrarotation of the apex of the heart and abnormal drainage of the right pulmonary veins into the right atrium (Ersöz et al. 1992). Most reported human cases show unilateral hypoplasia, which occurs more frequently on the right side. However, the dog in this report had left lung hypoplasia with shifted cardiomediastinal structures. There was no abnormal drainage of the pulmonary veins into the right atrium. Frequent respiratory distress, recurrent pneumonia and episodes of cyanosis are the most common findings of horseshoe lung in humans (Freedom et al. 1986). Most clinical signs are associated with concurrent cardiovascular anomalies (e.g. atrial septal defects, ventricular septal defects, tetralogy of Fallot and hypoplastic left ventricle) (Ersöz et al. 1992, Salerno et al. 2010). Clinical signs and prognosis are strongly associated with cardiovascular anomalies, rather than the horseshoe lung itself. In one report, the patient had no concurrent cardiovascular anomalies and respiratory distress (Takeda et al. 1990). The dog in this report had no complex anomalies associated with the cardiovascular system, and thus no respiratory distress; the pulmonary anomaly was the only incidental finding. Hypoplastic lung was until recently considered a rare congenital anomaly; its exact cause is unknown. Horseshoe lung is usually associated with other anomalies such as cardiac lesions, bronchogenic cysts and diaphragmatic hernia (Albay et al. 2008). Several reports suggest that pulmonary hypoplasia remains asymptomatic even in people of advanced age (Kurkcuoglu et al. 2005). Compensatory hypertrophy of the contralateral lung and filling of the ipsilateral hemithorax may explain this finding. The cardiomediastinal structures of the dog were deviated to the left side with a hypoplastic left lung and hypertrophic right lung. These abnormalities presumptively were derived from the foregut during the embryological stage. The trachea and oesophagus are embryologically closely related and are separated by the tracheo-oesophageal septum. In humans, horseshoe lung is associated with bronchopulmonary foregut malformations coinciding with bilateral intralobar pulmonary sequestration, oesophageal atresia and oesophagobronchial fistula (Wales et al.
Journal of Small Animal Practice
•
Vol 55
•
May 2014
•
© 2014 British Small Animal Veterinary Association
Canine horseshoe lung
2002, Goldberg et al. 2006). The oesophageal abnormalities may be associated with deformation of the lung. The dog in this report fortunately showed only a modified course of the oesophagus without oesophageal atresia and oesophagobronchial fistula. Several imaging diagnostics indicated pulmonary and cardiomediastinal anomalies, but a definitive diagnosis would have required biopsy or post-mortem examination. Histopathological results would have distinguished between left lung hypoplasia and lung collapse. This canine case report represents a pulmonary anomaly (i.e. unilateral pulmonary hypoplasia with concurrent cardiomediastinal structural deviation) that appears similar to horseshoe lung in human medicine. Conflict of interest None of the authors of this article has a financial or personal relationship with other people or organisations. References Albay, S., Cankal, F., Tunali, S., et al. (2008) Unilateral pulmonary hypoplasia. International Journal of Anatomical Variations 1, 23-25
Journal of Small Animal Practice
•
Vol 55
•
May 2014
•
Currarino, G. & Williams, B. (1985) Causes of congenital unilateral pulmonary hypoplasia: a study of 33 cases. Pediatric Radiology 15, 15-24 Ersöz, A., Soncul, H., Gökgöz, L., et al. (1992) Horseshoe lung with left lung hypoplasia. Thorax 47, 205-206 Frank, J. L., Poole, C. A. & Rosas, G. (1986) Horseshoe lung: clinical, pathologic, and radiologic features and a new plain film finding. American Journal of Roentgenology 146, 217-226 Freedom, R. M., Burrows, P. E. & Moes, C. A. (1986) “Horseshoe” lung: report of five new cases. American Journal of Roentgenology 146, 211-215 Goldberg, S., Ringertz, H. & Barth, R. A. (2006) Prenatal diagnosis of horseshoe lung and esophageal atresia. Pediatric Radiology 36, 983-986 Goo, H. W., Kim, Y. H., Ko, J. K., et al. (2002) Horseshoe lung: useful angiographic and bronchographic images using multidetector-row spiral CT in two infants. Pediatric Radiology 32, 529-532 Hawass, N. D., Badawi, M. G., Al-Muzrakchi, A. M., et al. (1990) Horseshoe lung: differential diagnosis Pediatric Radiology 20, 580-584 Kurkcuoglu, I. C., Eroglu, A., Karaoglanoglu, N., et al. (2005) Pulmonary hypoplasia in a 52-year-old woman. The Annals of Thoracic Surgery 79, 689-691 Oguz, B., Alan, S., Ozcelik, U., et al. (2009) Horseshoe lung associated with leftlung hypoplasia, left pulmonary artery sling and bilateral agenesis of upper lobe bronchi. Pediatric Radiology 39, 1002-1005 Salerno, T., Guccione, P., Malena, S., et al. (2010) Horseshoe lung associated with unique left pulmonary vein: an unreported association. Pediatric Cardiology 31, 905-907 Takeda, K., Kato, N., Nakagawa, T., et al. (1990) Horseshoe lung without respiratory distress. Pediatric Radiology 20, 604 Wales, P. W., Drab, S. A., Connolly, B., et al. (2002) Horseshoe lung in association with other foregut anomalies: what is the significance? Journal of Pediatric Surgery 37, 1205-1207
© 2014 British Small Animal Veterinary Association
277
CASE REPORT
Unusual congenital pulmonary anomaly with presumed left lung hypoplasia in a young dog C. M. Lee*, J. H. Kim†, M. H. Kang*, K. D. Eom† and H. M. Park* *Department of Veterinary Internal Medicine, College of Veterinary Medicine, Konkuk University, Seoul 143-701, South Korea †Department of Veterinary Radiology and Diagnostic Imaging, College of Veterinary Medicine, Konkuk University, Seoul 143-701, South Korea
A seven-month-old, entire, male miniature schnauzer dog was referred with acute vomiting, inappetence and depression primarily as a result of a gastric foreign body (pine cones). During investigations, thoracic radiographs revealed increased volume of the right lung lobes, deviated cardiomediastinal structures and elevation of the heart from the sternum. Thoracic computed tomography revealed left cranial lung lobe hypoplasia and extension of the right cranial lung parenchyma across the midline to the left hemithorax. Branches of the right pulmonary vessels and bronchi also crossed the midline and extended to the left caudal lung lobe. These findings suggested that the right and left lungs were fused. In humans this finding is consistent with horseshoe lung, which is an uncommon congenital malformation. To the authors’ knowledge, this case represents the first report of such a pulmonary anomaly in a dog.
Journal of Small Animal Practice (2014) 55, 274–277 DOI: 10.1111/jsap.12192 Accepted: 23 December 2013; Published online: 17 March 2014
INTRODUCTION
CASE HISTORY
Horseshoe lung is a rare congenital pulmonary anomaly in which the pulmonary parenchyma extends from the lung base across the midline and fuses with the base of the contralateral lung (Frank et al. 1986). Approximately 40 cases have been reported in humans, mostly associated with hypoplasia of the right lung, dextrarotation of the apex of the heart and abnormal drainage of the right pulmonary veins into the right atrium (Frank et al. 1986, Ersöz et al. 1992). Pulmonary hypoplasia represents a broad range of malformations characterised by incomplete development of lung tissue, and includes a spectrum of concurrent problems (e.g. hypoplasia, aplasia and agenesis of selected lung segments or all lung segments) (Currarino & Williams 1985). Early clinical signs in neonates, infants and children primarily relate to respiratory problems. The most common findings are frequent respiratory distress, recurrent pneumonia and episodes of cyanosis (Frank et al. 1986). To the authors’ knowledge, this report is the first to describe a dog that presumably had horseshoe lung with left lung hypoplasia. 274
A seven-month-old, entire, male miniature schnauzer dog was presented with acute vomiting, inappetence and depression. Physical examination findings included dehydration, abdominal pain and muffled heart sounds on the right side of the heart. Blood biochemistry analysis revealed hyponatraemia (136 mmol/L; reference interval: 141 to 152 mmol/L), hypokalaemia (2·5 mmol/L; reference interval: 3·8 to 5·0 mmol/L) and hypochloraemia (95 mmol/L; reference interval: 102 to 117 mmol/L). Other serum chemistry values, blood gas analysis and complete blood count results were within their respective reference intervals. Thoracic radiography revealed hyperlucent right lung lobes with increased volume and left-sided mediastinal shift, rotation of the apex of the heart towards the left side, elevation of the heart from the sternebrae and an asymmetrical diaphragm (Fig 1A, B). Further cardiopulmonary examinations were performed because the lung pattern was suggestive of reduced pulmonary perfusion. An electrocardiogram demonstrated left shift of the mean electrical axis, but echocardiography showed no structural or functional
Journal of Small Animal Practice
•
Vol 55
•
May 2014
•
© 2014 British Small Animal Veterinary Association
Canine horseshoe lung
FIG 1. (A) Ventrodorsal and (B) left lateral thoracic radiographs. Leftsided displacement of cardiomediastinal structures, elevation of the heart from the sternum and cranially displaced diaphragm of the left side are present. (The dog’s right side is displayed on the left.) There is increased volume of the right lung lobe (white arrows). (C) The contrastenhanced dorsal reconstruction computed tomography (CT) image shows displacement of the mediastinum, including the oesophagus. (D) The postcontrast transverse CT image shows left-sided deviation of the cardiomediastinal structures. The mediastinum is displaced and lying adjacent to the thoracic wall
abnormalities. Abdominal radiography and ultrasonography revealed a gastrointestinal foreign body. The foreign body and the course of the oesophagus in relation to the mediastinal shift were evaluated by barium contrast study. This revealed a modified oesophageal course owing to the increased volume of the right lung lobes. From the diagnostic imaging findings (increased volume of the right hemithorax and mediastinal shift), the differential diagnoses were unilateral lung collapse, pneumothorax and unilateral pulmonary emphysema with compensatory hyperinflation. To further investigate the pulmonary abnormalities, a multidetector computed tomography (CT) examination was performed under general anaesthesia. The CT parameters were 120 kVp, 200 mAs and 1·250-mm slice thickness without gantry tilting. The CT images revealed deviation of the heart with a hypoplastic left cranial lung lobe. The right lung lobes and accessory lung lobe were significantly enlarged. Because of the asymmetric lungs, the mediastinal structures (including the oesophagus and heart) were deviated to the left side. The oesophagus had an anomalous course (Fig 1C, D). Gastric foreign bodies were present. Transverse CT images with a lung window setting revealed an anomalous branch from the right bronchi and pulmonary vessels in the cranial lobe that crossed the midline to the left hemithorax (Fig 2A to D). The bronchus and pulmonary vessels in the right
FIG 2. (A to D) Contiguous transverse computed tomography (CT) images in the lung window show that the bronchi in the right cranial lung lobe cross the midline to the left hemithorax. (The dog’s right side is displayed on the left.) The white arrowhead indicates the course of the bronchi in serial CT images. (E to I) Contiguous transverse CT images in the lung window show that the bronchi cross the right caudal lobe through the accessory lobe to left hemithorax. The lobar bronchi of the accessory lobe from the right main bronchus extend to the left caudal lobe (white arrow). A, accessory lobe; Lc, left caudal lobe; Rc, right caudal lobe Journal of Small Animal Practice
•
Vol 55
•
May 2014
•
© 2014 British Small Animal Veterinary Association
275
C. M. Lee et al.
FIG 3. Contrast-enhanced computed tomography (CT) angiography of (A) the right cranial lung lobe and (B) caudal lung lobes. (The dog’s right side is displayed on the left.) On the transverse images, the right cranial and caudal pulmonary vessels pass from the right side through midline to the left side. The accessory pulmonary vessels extend to the left caudal lung lobe (white arrowhead). A, accessory lobe; Lc, left caudal lobe; Rc, right caudal lobe
caudal lung lobe crossed the midline. The lobar bronchi of the accessory lobe connected directly to the left caudal lobar bronchi (Fig 2E to I). Contrast-enhanced CT images (lung window setting) revealed that right pulmonary vessels arose from the right side and extended to the left side (Fig 3). The pulmonary artery in the accessory lung lobe extended to the left caudal lung lobe. Three-dimensional volume-rendered CT images revealed that the increased right lung volume and the right bronchi extended from the right bronchus to the left lung lobe parenchyma. Despite the radiological findings of pulmonary deformation, the chief complaint was acute vomiting associated with a gastric foreign body. The gastric foreign body required removal before the relationship between the clinical signs and the anomalous course of the oesophagus could be evaluated. The gastric foreign body was removed by gastroscopy. Endoscopic findings revealed a distorted oesophageal lumen; hyperaemic mucous membranes of the oesophagus, stomach and duodenum; and the gastric foreign body. After retrieving the foreign body (a pine cone), the dog was treated with 44 mg/kg/day ampicillin (Amcillin; Chong Kun Dang Pharmaceutical Corp.) and 10 mg/kg/day cimetidine (Cimetidine; Nelson Pharm Korea) twice a day orally to control postoperative complications such as oesophagitis and gastritis. One week after the operation, the dog had no clinical signs, but the oesophageal course remained modified. The dog was discharged without additional treatment and in good physical condition.
DISCUSSION In human medicine, horseshoe lung is a rare congenital malformation in which pulmonary tissue extends from one side of the lung and fuses with the contralateral lung (Frank et al. 1986, Ersöz et al. 1992). The airway and arterial supplies to the isthmic portion of a horseshoe lung branch from the hypoplastic lung (Goo et al. 2002, Oguz et al. 2009). 276
One study reported that normal canine thoracic radiological findings are similar to human horseshoe lung anomalies because the classic anatomical description of the dog lung includes an accessory lobe in the midline (Hawass et al. 1990). However, the description only focuses on anatomical differences between species, not on the fusion between any lung lobes. From the human perspective, an accessory lobe in the midline is not normally present because humans have a completely separated hemithorax. By contrast dogs have an accessory lobe in the midline and incomplete thoracic separation by the thin pleura. Because of these anatomical differences, the features of a canine lung anomaly suspicious for horseshoe lung may be different from that described in humans. The canine lung has no isthmic portion, which reportedly is an important feature of horseshoe lung in humans. Anatomical differences in lung arrangement in humans and dogs may explain the dissimilarity of the fused form. In the authors’ opinion, because of these features, fusion of both sides of the lungs could be formed more commonly in dogs than in humans. The most common concurrent findings in humans are hypoplasia of the right lung, dextrarotation of the apex of the heart and abnormal drainage of the right pulmonary veins into the right atrium (Ersöz et al. 1992). Most reported human cases show unilateral hypoplasia, which occurs more frequently on the right side. However, the dog in this report had left lung hypoplasia with shifted cardiomediastinal structures. There was no abnormal drainage of the pulmonary veins into the right atrium. Frequent respiratory distress, recurrent pneumonia and episodes of cyanosis are the most common findings of horseshoe lung in humans (Freedom et al. 1986). Most clinical signs are associated with concurrent cardiovascular anomalies (e.g. atrial septal defects, ventricular septal defects, tetralogy of Fallot and hypoplastic left ventricle) (Ersöz et al. 1992, Salerno et al. 2010). Clinical signs and prognosis are strongly associated with cardiovascular anomalies, rather than the horseshoe lung itself. In one report, the patient had no concurrent cardiovascular anomalies and respiratory distress (Takeda et al. 1990). The dog in this report had no complex anomalies associated with the cardiovascular system, and thus no respiratory distress; the pulmonary anomaly was the only incidental finding. Hypoplastic lung was until recently considered a rare congenital anomaly; its exact cause is unknown. Horseshoe lung is usually associated with other anomalies such as cardiac lesions, bronchogenic cysts and diaphragmatic hernia (Albay et al. 2008). Several reports suggest that pulmonary hypoplasia remains asymptomatic even in people of advanced age (Kurkcuoglu et al. 2005). Compensatory hypertrophy of the contralateral lung and filling of the ipsilateral hemithorax may explain this finding. The cardiomediastinal structures of the dog were deviated to the left side with a hypoplastic left lung and hypertrophic right lung. These abnormalities presumptively were derived from the foregut during the embryological stage. The trachea and oesophagus are embryologically closely related and are separated by the tracheo-oesophageal septum. In humans, horseshoe lung is associated with bronchopulmonary foregut malformations coinciding with bilateral intralobar pulmonary sequestration, oesophageal atresia and oesophagobronchial fistula (Wales et al.
Journal of Small Animal Practice
•
Vol 55
•
May 2014
•
© 2014 British Small Animal Veterinary Association
Canine horseshoe lung
2002, Goldberg et al. 2006). The oesophageal abnormalities may be associated with deformation of the lung. The dog in this report fortunately showed only a modified course of the oesophagus without oesophageal atresia and oesophagobronchial fistula. Several imaging diagnostics indicated pulmonary and cardiomediastinal anomalies, but a definitive diagnosis would have required biopsy or post-mortem examination. Histopathological results would have distinguished between left lung hypoplasia and lung collapse. This canine case report represents a pulmonary anomaly (i.e. unilateral pulmonary hypoplasia with concurrent cardiomediastinal structural deviation) that appears similar to horseshoe lung in human medicine. Conflict of interest None of the authors of this article has a financial or personal relationship with other people or organisations. References Albay, S., Cankal, F., Tunali, S., et al. (2008) Unilateral pulmonary hypoplasia. International Journal of Anatomical Variations 1, 23-25
Journal of Small Animal Practice
•
Vol 55
•
May 2014
•
Currarino, G. & Williams, B. (1985) Causes of congenital unilateral pulmonary hypoplasia: a study of 33 cases. Pediatric Radiology 15, 15-24 Ersöz, A., Soncul, H., Gökgöz, L., et al. (1992) Horseshoe lung with left lung hypoplasia. Thorax 47, 205-206 Frank, J. L., Poole, C. A. & Rosas, G. (1986) Horseshoe lung: clinical, pathologic, and radiologic features and a new plain film finding. American Journal of Roentgenology 146, 217-226 Freedom, R. M., Burrows, P. E. & Moes, C. A. (1986) “Horseshoe” lung: report of five new cases. American Journal of Roentgenology 146, 211-215 Goldberg, S., Ringertz, H. & Barth, R. A. (2006) Prenatal diagnosis of horseshoe lung and esophageal atresia. Pediatric Radiology 36, 983-986 Goo, H. W., Kim, Y. H., Ko, J. K., et al. (2002) Horseshoe lung: useful angiographic and bronchographic images using multidetector-row spiral CT in two infants. Pediatric Radiology 32, 529-532 Hawass, N. D., Badawi, M. G., Al-Muzrakchi, A. M., et al. (1990) Horseshoe lung: differential diagnosis Pediatric Radiology 20, 580-584 Kurkcuoglu, I. C., Eroglu, A., Karaoglanoglu, N., et al. (2005) Pulmonary hypoplasia in a 52-year-old woman. The Annals of Thoracic Surgery 79, 689-691 Oguz, B., Alan, S., Ozcelik, U., et al. (2009) Horseshoe lung associated with leftlung hypoplasia, left pulmonary artery sling and bilateral agenesis of upper lobe bronchi. Pediatric Radiology 39, 1002-1005 Salerno, T., Guccione, P., Malena, S., et al. (2010) Horseshoe lung associated with unique left pulmonary vein: an unreported association. Pediatric Cardiology 31, 905-907 Takeda, K., Kato, N., Nakagawa, T., et al. (1990) Horseshoe lung without respiratory distress. Pediatric Radiology 20, 604 Wales, P. W., Drab, S. A., Connolly, B., et al. (2002) Horseshoe lung in association with other foregut anomalies: what is the significance? Journal of Pediatric Surgery 37, 1205-1207
© 2014 British Small Animal Veterinary Association
277
