IMAGING DIAGNOSIS: CONGENITAL LOBAR EMPHYSEMA IN AN OLD

ENGLISH SHEEPDOG PUPPY

COLLEEN MITCHELL, STEPHANIE NYKAMP

Signalment

SIX-WEEK-OLD, female, Old English Sheepdog.

History

Five days before presentation to the Ontario Veterinary

College the puppy had acute tachypnea, diarrhea, and

lethargy. In thoracic radiographs at that time there was

elevation of the cardiac silhouette from the sternum, a gas

opacity in the ventral thorax and a left mediastinal shift. A

tentative diagnosis of pneumothorax was made but no ad-

ditional diagnostic tests or treatment were performed. On

abdominal sonography, an intussusception in the right ab-

domen and fluid distension of the stomach were found. An

exploratory laparotomy was performed. An ileocolic in-

tussusception was identified and reduced and 4 cm of de-

vitalized ileum was resected. Three days postoperatively the

puppy remained tachypneic and decreased breath sounds

were noted in the right thorax. Thoracocentesis was per-

formed twice from the right side yielding 30ml of air each

time. Subsequent to thoracocentesis the dyspnea pro-

gressed and in thoracic radiographs the pneumothorax ap-

peared to have progressed.

Physical Examination

When examined at the Ontario Veterinary College

Teaching Hospital, the patient was in respiratory distress.

There was tachypnea (44bpm), dyspnea, mild hypothermia

(temperature 37.71C), tachycardia (160bpm), and pink

mucous membranes.

Radiographic Findings

In thoracic radiographs there was severe hyperinflation

of the right middle lung lobe with a rounded contour, and

a mildly thick pleural surface (Fig. 1). Vessels could be seen

within the right middle lung lobe. The heart was displaced

to the left. There was a small amount of gas in the pleural

space. At the cranial aspect of the right middle lung lobe,

there was an alveolar lung pattern silhouetting with the

cranial aspect of the heart. The assessment was congenital

bulla and malformation of the right middle lung lobe.

Diagnosis/Outcome

A thoracotomy was performed and the emphysematous

right middle lung lobe was removed. The remaining lung

lobes appeared normal. The patient recovered from the tho-

racotomy and was released from hospital the following day.

The right middle lung lobe was submitted for histo-

pathologic examination. In all sections examined there was

enlargement and hyperinflation of alveoli, with some loss

and/or displacement of alveolar walls. There were multi-

focal regions of parenchymal necrosis with hemorrhage.

Bronchial cartilage abnormalities were not found. The his-

topathologic diagnosis was lobar emphysema with multi-

focal hemorrhagic infarcts. These findings are consistent

with congenital lobar emphysema, a congenital disorder

recognized in puppies and children.

Discussion

The development of the lungs begins as a ventral di-

verticulum of the foregut starting at the level of the fourth

pharyngeal pouch. The lung bud grows caudoventrally into

the mesoderm ventral to the esophagus and bifurcates to

form the principal bronchi. The adjacent mesoderm will

become the connective tissue and cartilage of the tracheal

wall. Repeated branching of the lung bud results in lobar

and segmental bronchi, bronchioles, and alveoli.1,2 Anom-

alies develop when cells migrate independently from the

original lung bud. In people congenital lung malformations

include pulmonary sequestration, congenital cystic aden-

omatoid malformation, bronchogenic cysts, and congenital

lobar emphysema. Combinations of these anomalies in

children verify their common origin.3 Congenital lobar

emphysema is a congenital over-expansion of a pulmonary

lobe. This is most often idiopathic, but can occur second-

ary to a defect in bronchial cartilage, intraluminal

bronchial obstruction or by extraluminal bronchial

compression.4 Cartilage defects can result in air trapping

by dynamic bronchial collapse.3,5–7 Intraluminal obstruc-

tion can occur from mucous plugs, mucosal folds, or se-

ptae.4 Congenital lobar emphysema in children has been

associated with cardiac defects, notably ventricular septal

Address correspondence and reprint requests to Dr. Colleen Mitchell,at the above address.E-mail: mitchelc@uoguelph.ca

Received January 20, 2006; accepted for publication February 16, 2006.doi: 10.1111/j.1740-8261.2006.00178.x

From the Ontario Veterinary College, University of Guelph, Guelph,ON, Canada N1G 2W1.

465

defects, atrial septal defects, patent ductus arteriosus, and

coarctation of the aorta.3,4,8

Congenital lobar emphysema has been identified as a

cause of respiratory distress in puppies and in adult dogs.

Clinical signs include coughing, exercise intolerance, ta-

chypnea, dyspnea, and inappetence.9–17 There are four re-

ports of successful treatment of congenital lobar

emphysema in dogs with lobectomy.9,15–17 The right mid-

dle lung lobe was most commonly affected, followed by the

left cranial lung lobe. Reports also describe congenital

lobar emphysema of multiple lobes.10,12,14 There is one re-

port of torsion of the affected lung lobes.14 Congenital

lobar emphysema in dogs is usually associated with car-

tilage dysplasia or hypoplasia. The cause of the emphyse-

ma in our patient was not found, indicating an idiopathic

cause or that the inciting cause was proximal to the point

of excision.

Radiographic findings of congenital lobar emphysema

include lobar hyperinflation with pulmonary blood vessels

extending to the lobe margin, contralateral mediastinal

shift, caudal displacement of the diaphragm (unilateral or

bilateral), thoracic cavity enlargement, atelectasis of unaf-

fected lobes and possibly pneumothorax.2–6,9,11–18 In hu-

mans, these findings in a neonate with respiratory distress

are diagnostic for congenital lobar emphysema and also

determine the location for surgical intervention.6 To con-

firm the diagnosis, thoracic radiographs made at full in-

spiration vs. expiration can be compared. An

emphysematous lung will not deflate with expiration.2,18

These radiographs help differentiate an emphysematous

lung from pneumothorax, preventing unnecessary thor-

acocentesis that can result in tension pneumothorax in pa-

tients with congenital lobar emphysema.2,6,9 Positional

radiography can also be helpful in differentiating pneumo-

thorax from a cystic lung lesion because the anatomic re-

lationship of the hyperlucent lung lesion to the thoracic

viscera and thoracic wall is independent of positioning.11 If

the diagnosis cannot be made from radiographs, additional

diagnostic tests that may be of value include computed

tomography, pulmonary scintigraphy, vascular studies

(contrast angiography or magnetic resonance angio-

graphy), and bronchoscopy.4,8,15,18,19

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Fig. 1. Left lateral (A) and ventrodorsal (B) thoracic radiographs ob-tained shortly after admission. There is severe hyperinflation of the rightmiddle lung lobe with a rounded contour, a mildly thick pleural surface,cranial alveolar pattern and displacement of the heart to the left. Vessels canbe seen within the right middle lung lobe. A small amount of gas is present inthe pleural space adjacent to the right middle lung lobe.

466 Mitchell and Nykamp 2006

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467Congenital Lobar EmphysemaVol. 47, No. 5