Computed tomographic characterization of the pulmonary system in clinically normal alpacas.

OBJECTIVE: To characterize and quantitatively assess the typical pulmonary anatomy of healthy adult alpacas with multidetector row CT.

ANIMALS: 10 clinically normal adult female alpacas.

PROCEDURES: CT examination of the thorax was performed before and after IV administration of iodinated contrast medium in sedated alpacas in sternal recumbency. Measurements of the trachea, bronchi and related blood vessels, and selected vertebrae as well as the extent and density of lung parenchyma were performed with a Digital Imaging and Communications in Medicine (DICOM) viewer. Morphometric and quantitative data were summarized.

RESULTS: Separation of individual lung lobes could not be identified, except for the accessory lung lobe. In all alpacas, both lungs extended farther caudally at the medial aspect than at the lateral aspect. The right lung extended farther in both cranial and caudal directions than did the left lung. The branching pattern of the bronchial tree varied only slightly among alpacas and consisted of 1 cranial bronchus and 3 caudal bronchi bilaterally, with a right accessory bronchus. Luminal diameters of first-generation bronchi ranged from 3 to 9 mm. Mean ± SD parenchymal lung density was -869 ± 40 Hounsfield units (HU) before contrast injection and -825 ± 51 HU after contrast injection. Mean difference in diameter between bronchi and associated arteries or veins was 0.8 ± 0.9 mm.

CONCLUSIONS AND CLINICAL RELEVANCE: Knowledge of the typical anatomy of the lungs and bronchial tree in healthy alpacas as determined via CT will aid veterinarians in clinical assessment and bronchoscopic evaluation of alpacas.