SummaryA 25-year-old Haflinger gelding was evaluated for chronicprogressive unilateral exophthalmos. Ultrasonographic investigation and magnetic resonance (MR) imaging revealed a retrobulbar space-occupying mass to be the cause of eyeball displacement. Ultrasonographic features were not sufficient to specify the type and extension of the lesion. Magnetic resonance scans, however, clearly displayed an infiltrative intracranial growth pattern but sparing of orbital soft tissues. Based on MR appearance, tentative diagnosis of an orbital soft tissue neoplasia was made and subsequently confirmed by histopathological investigation. The latter revealed a poorly differentiated neuroendocrine tumour. Retrospectively, MR changes resembled those seen with neuroendocrine neoplasms of the human skull. Even if histopathology remains to be elucidated by cytological or histological inspection, MR imaging of equine orbital tumours should provide the criteria necessary for evaluating the therapeutic options and associated prognosis.

High resolution ultrasound in equine ophthalmologyUltrasonographic evaluation of equine eyes has become routine in horses with opaque media. Depiction of the internal structures of the eye using conventional ultrasound has been restricted to the lens, vitreous, posterior segment of the eye, and the orbit. Previously, it was not possible to display the anterior segment in an acceptable quality. In this study, a high resolution linear-array ultrasound probe with a median frequency of 12 MHz was applied for the first time in equine ophthalmology to display both the anterior and posterior segments of the eye. This research project concentrated primarily on the anterior segment of the eye. Normal anatomy, as well as some specific eye problems, could be displayed. This study was comprised of 75 horses of various age, sex, and breed. All of the horses were treated in the Equine Clinic, Ludwig-Maximilians-University, Munich, Germany from 16.12.2002 to 01.08.2003. The device for this application was a Siemens SONOLINE? Omnia with the linear-array-transducer VF 13 -5. (Software edition 2.1). The probe is known as a "near-field-transducer" and is capable of displaying high resolution images in the immediate vicinity of the contact surface. High definition ocular ultrasonography provides the examiner with images of unprecedented quality from healthy as well as pathologically changed equine eyes. The resulting images resembled those of lower magnification histological sections. In this study, in addition to the posterior segment of the eye, it was also possible to view several anterior structures, such as: cornea, iris, iridocorneal angle, ciliary body, posterior chamber, as well as the lens in unparalleled quality. The iridocorneal angle was measured on selected eyes. The clinical importance of these results has yet to be determined.

Diagnosis and therapy of periorbital diseases in horses: Indication for computed tomography (CT) or magnetic resonance tomography (MRT)During the last years, not only computed tomography (CT) but also magnetic resonance imaging (MRI) has been established in equine medicine. Tomographic examinations in horses are accompanied with high costs and efforts, and they are not available in every case. Certain diseases of the equine head cannot be interpreted or treated without tomographic images. On the other hand, the excellent improvement of information by tomographies justifies the costs and efforts in certain cases. Indications for CT or MRI in periorbital diseases are particularly protrusions of the globe due to retrobulbar or retroorbital tumor growth. In fractures temporal of the globe and suspicion of an injury of the temporo-mandibular joint the preoperative knowledge of the CT or MRI images provides a tremendous advantage for surgery. In tumor diagnostic, information from MRI-images is superior to information from CT-images, and in periocular fractures, information from CT-images is superior to that from MRI-images. Basically, both techniques are particular suitable for verifying an indication for surgery as well as for evaluating the prognosis and for detailed planning of the optimal surgical approach. In some cases, the costs for surgeries with a poor or infaust prognosis can be avoided. In other cases, information from CT or MRI images is a vital condition for preserving the globe or even vision.

ZusammenfassungDurch kernspintomographische Untersuchung von drei Schimmeln mit Umfangsvermehrungen im Kopfbereich konnten Melanome relativ gut abgegrenzt werden. Einerseits ließ sich das Ausmaß der Veränderung ermitteln, andererseits war ein typisches Verhalten des Melanoms auffällig: ein Ansteigen der Signalintensität in T1 gewichteten Sequenzen und ein Abfall des Signals in T2 gewichteten Sequenzen konnte bei 3 Pferden nachgewiesen werden. Damit verhielten sich die untersuchten Melanome umgekehrt zu den im Bereich des Pferdekopfes bisher beschriebenen Tumoren, tumorähnlichen und chronisch entzündlichen Veränderungen und waren damit differenzierbar.Schlüsselwörter: Pferd, Kopf, Melanom, MRT, Tumor Magnetic resonance imaging of melanomas in the head region of 3 horsesMagnetic resonance imaging (MRI) can be very useful in differentiating melanomas from other masses of the equine head in 3 grey horses. The dimensions of the mass can be determined and typical melanoma appearance was recognizable during MRI examination. Shorter T1 and T2 relaxation times were observed in these tumors. All of the melanomas identified in this report reacted opposite to other described forms of neoplasia, tumor-like masses, and changes due to chronic inflammation commonly identified in the heads of horses, thus allowing their differentiation.