MAGNETIC RESONANCE IMAGING OF THE NORMAL EYE AND ORBIT OF A SCREECH OWL (OTUS ASIO)

Imaging characteristics of the eyes of cinereous vulture (Aegypius monachus): morphology and comparative biometric measurement

The aim of this study is to describe radiographic, ultrasonographic, and computed tomographic appearance of normal cinereous vulture’s eye and to determine normal biometric values of intraocular structures. Twenty-six eyes of thirteen healthy cinereous vultures were examined. Under general anesthesia with isoflurane, ultrasonography (US), computed tomography (CT) and skull radiography were performed. Differences between both eyes as well as between US and CT measurements were investigated and correlation of measurements between both eyes as well as correlation between CT and US measurements of the various ocular structures were calculated. Most of paired data did not show any significant differences between both eyes and the CT and US measurements, while there were significant differences (P<0.05) between CT and US measurements of depth of both vitreous and anterior chambers, and axial length of the lens in right eyes. There was also a significant difference (P<0.05) between both eyes in depth of vitreous measured by CT. All the measurements had strong correlations between both eyes and between US and CT. In conclusion, ocular imaging techniques provided useful data of biometry and morphology, showing good correlation between CT and US in cinereous vulture’s eye. Especially, when ophthalmoscopic examinations would not be available due to opaque anterior segment, imaging techniques could be essential for diagnosing and managing of the eye.

Principles of neurological imaging of exotic animal species

Because the central nervous system (CNS) is encased almost entirely in bone, the means by which the clinician can evaluate it are limited. Additionally, the small size of many exotic companion animals further complicates diagnostic evaluation of the brain and spinal cord. Knowledge of the advantages and limitations of different imaging modalities, along with the neuroanatomical localization and assessment of likely causes of disease, will permit the clinician to choose the most appropriate imaging method for the patient. This article discusses the basic imaging principles of radiology, myelography, CT, and MRI of the nervous system of companion exotic animals to aid exotic animal clinicians in selecting imaging modalities and interpreting the results.

The avian neurologic examination and ancillary neurodiagnostic techniques: a review update

The purpose of this article is to guide the avian clinician in the assessment of neurologic function in birds. Physical and neurologic examinations that evaluate cranial nerves, postural reactions, and spinal reflexes identify neurologic dysfunction and the corresponding anatomic location of the lesion. Ancillary diagnostic tests, such as cerebrospinal fluid analysis, diagnostic imaging, muscle and nerve histology, and electrodiagnostics, are tools to confirm and clarify conclusions from the neurologic examination and to identify the cause of disease. Once the disease location and pathologic process have been identified, appropriate treatment and prognosis may be provided.

ULTRASONOGRAPHIC AND COMPUTED TOMOGRAPHIC EXAMINATIONS OF THE AVIAN EYE: PHYSIOLOGIC APPEARANCE, PATHOLOGIC FINDINGS, AND COMPARATIVE BIOMETRIC MEASUREMENT

Ultrasonography (US) and computed tomography (CT) were performed after routine ophthalmologic and ophthalmoscopic examinations in 190 eyes of six various diurnal (common buzzard [Buteo buteo L., 1758], n = 20; common kestrel [Tinnunculus tinnunculus L., 1758], n = 20) and nocturnal raptor species (barn owl [Tyto alba L., 1758], n = 22; tawny owl [Strix aluco L., 1758], n = 8; long-eared owl [Asio otus L., 1758], n = 5; horned owl [Bubo bubo L., 1758], n = 1); and domestic pigeons (Columba livia, Gmel., 1789; n = 19), with a total of 95 individuals. Pathologic findings such as lens subluxation and luxation, intravitreal hemorrhage, detached retina, post-traumatic partial sequestration, or malformation of the pecten could be demonstrated with diagnostic imaging tools, while opacities of cornea or lens constrained direct ophthalmoscopic examination. The results proved US to be a quick noninvasive imaging technique for detailed ocular diagnoses. CT provided detailed information of the bony skull and bony scleral rings as well as adequate visualization of shape, size, and margination of the eye and lens. Nevertheless, CT was unable to differentiate subtle structures within the vitreous like the pecten oculi or hemorrhage. Biometric measurements were carried out to objectify imaging results. Results showed good correlation of depth and width of the anterior eye chamber, lens and vitreous, length of the bulbus, and the pecten but no correlation of cornea and posterior wall thickness was found.

The eye and orbit

Computed tomography (CT) and magnetic resonance imaging (MRI) provide excellent morphological detail of the eye and its associated structures. In veterinary medicine, these imaging modalities are most often used to diagnose and determine the extent of ocular or periocular tumors. They may also be used to diagnose inflammatory conditions of the orbital region and to determine the severity and extent of ocular trauma. This article reviews the applications of CT and MRI for ocular and orbital diseases, discusses normal findings, and presents representative case examples.