What Is Your Diagnosis?

Daniele Della Santa Dipartimento di Clinica Veterinaria, Facoltà di Medicina Veterinaria, Università di Pisa, 56010 San Piero a Grado (PI), Italy

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Veronica Marchetti Dipartimento di Clinica Veterinaria, Facoltà di Medicina Veterinaria, Università di Pisa, 56010 San Piero a Grado (PI), Italy

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Johann Lang Division of Clinical Radiology, Department of Clinical Veterinary Medicine, Vetsuisse Faculty, University of Bern, 3001 Bern, Switzerland

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Simonetta Citi Dipartimento di Clinica Veterinaria, Facoltà di Medicina Veterinaria, Università di Pisa, 56010 San Piero a Grado (PI), Italy

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History

A 6-year-old sexually intact male Yorkshire Terrier was evaluated because of a nonproductive cough and dyspnea of 10 days' duration. The dog had been treated with amoxicillin-clavulanic acid and betamethasone without apparent improvement. Three days before evaluation, the dog became anorectic and had signs of depression. On physical examination, the dog had labored breathing and was tachypneic. Abnormalities detected on CBC and microscopic examination of a blood smear included a stress leukogram (leukocytosis, mature neutrophilia, and lymphopenia), poikilocytosis, and activated monocytes. The serum glucose concentration was 65.7 mg/dL (reference range, 80 to 120 mg/dL). Radiographs of the thorax were obtained (Figure 1).

Figure 1—
Figure 1—

Left lateral (A) and ventrodorsal (B) radiographic views of the thorax of a 6-year-old Yorkshire Terrier evaluated because of a nonproductive cough and dyspnea of 10 days' duration.

Citation: Journal of the American Veterinary Medical Association 229, 11; 10.2460/javma.229.11.1725

Determine whether additional imaging studies are required, or make your diagnosis from Figure 1—then turn the page

Radiographic Findings and Interpretation

Severe, unilateral, right-sided pleural effusion with minimal contralateral shifting of the mediastinum and a homogeneous soft tissue opacity can be seen in the region of the right middle lung lobe (Figure 2). The lobar bronchus of the right middle lung lobe cannot be clearly identified.

Figure 2—
Figure 2—

Same ventrodorsal radiographic view as in Figure 1. Unilateral right-sided pleural effusion is evident. The cranial mediastinum is minimally shifted to the left of midline, whereas the caudal mediastinum is radiographically normal. A homogeneous soft tissue opacity is visible in the region of the right middle lung lobe (arrows).

Citation: Journal of the American Veterinary Medical Association 229, 11; 10.2460/javma.229.11.1725

Comments

Ultrasonography of the thorax revealed a moderate amount of slightly echoic pleural fluid. The right middle lung lobe was large with a globular appearance and was hypoechoic at the periphery; a small, centrally located area of clustered, reverberating foci consistent with gas was also visible (Figure 3). The bronchi were filled with fluid. Blood flow was not detected via color-flow, power, or spectral Doppler ultrasonography. The ventral portions of adjacent lung lobes were atelectatic; in those lung lobes, Doppler ultrasonography permitted detection of venous blood flow. The most likely differential diagnoses included torsion of the right middle lung lobe or abscess formation with secondary pleuritis. Trauma or neoplasia-induced consolidation of the right middle lung lobe and secondary pleural effusion were considered as less likely differential diagnoses. Torsion of the right middle lung lobe was confirmed during thoracotomy, and a lobectomy was performed. The dog recovered from surgery and anesthesia without complications.

Figure 3—
Figure 3—

Ultrasonographic image of the thorax of the dog in Figure 1. The right middle lung lobe is large and hypoechoic at the periphery; reverberating echoes compatible with gas can be seen in its central portion (arrowheads).

Citation: Journal of the American Veterinary Medical Association 229, 11; 10.2460/javma.229.11.1725

Lung lobe torsion is an uncommon condition characterized by rotation of a lung lobe around its axis; torsion usually occurs at the level of or in close proximity to the hilus. It causes vascular compromise leading to congestion, edema, and possibly hemorrhage and necrosis.1

Most cases of lung lobe torsion involve large, deepchested dogs (especially Afghan Hounds); however, the condition has been reported in several breeds including small, chondrodystrophic (especially Pugs) and toybreed dogs.2 Most commonly, the right middle (especially in deep-chested dogs and large-breed dogs with an intermediate conformation of the thorax) and left cranial lung lobe (especially in small, chondrodystrophic dogs) are affected.2 Rarely, multiple lung lobes can be affected.1 The most common radiographic signs are pleural effusion and increased opacity in the area of the affected lung lobe.1,3 Pleural effusion is usually bilateral (often asymmetric), but it can also be unilateral. The increased opacity (associated with loss of visualization of lobar vasculature) can be uniform or inhomogeneous because of the presence of gas in the affected lobe. Gas bubbles may be scattered throughout the affected lobe (vesicular lung pattern) or clustered in some portions.1 On ultrasonography, the affected lung lobe is usually large and hypoechoic; in most cases, centrally located, reverberating foci consistent with gas can be seen. In the dog reported here, gas clustered in the central portion of the affected lung lobe, detected during ultrasonography, was not detected on thoracic radiographs.

The treatment of choice is surgical removal of the affected lobe, which results in an uncomplicated recovery in approximately 50% of dogs.2 Toy-breed dogs appear to have a better prognosis than large-breed dogs.2

  • 1

    D'Anjou MA, Tidwell AS, Hecht S. Radiographic diagnosis of lung lobe torsion. Vet Radiol Ultrasound 2005;46:478484.

  • 2

    Neath PJ, Brockman DJ, King LG. Lung lobe torsion in dogs: 22 cases (1981–1999). J Am Vet Med Assoc 2000;217:10411044.

  • 3

    Suter PF. Lower airway and pulmonary parenchymal disease. In:Thoracic radiography: a text atlas of thoracic diseases of the dog and cat. Wettswill, Switzerland: PF Suter, 1984;517682.

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