MAGNETIC RESONANCE IMAGING CONTRAST ENHANCEMENT OF EXTRA‐OCULAR MUSCLES IN DOGS WITH NO CLINICAL EVIDENCE OF ORBITAL DISEASE

Enhancement of extra‐ocular muscles has been reported in cases of orbital pathology in both veterinary and medical magnetic resonance imaging. We have also observed this finding in the absence of orbital disease. The purpose of this retrospective study was to describe extra‐ocular muscle contrast enhancement characteristics in a group of dogs with no known orbital disease. Magnetic resonance images (MRI) from dogs with no clinical evidence of orbital disease and a reportedly normal MRI study were retrieved and reviewed. Contrast enhancement percentages of the medial, lateral, ventral, and dorsal rectus muscles were calculated based on signal‐to‐noise ratios that were in turn determined from hand‐traced regions of interest in precontrast, immediate postcontrast and 10‐min postcontrast scans. Comparison measurements were made in the pterygoid muscle. Contrast enhancement of the extra‐ocular muscles was observed in all patients (median contrast enhancement percentage 45.0%) and was greater than that of pterygoid muscle (median contrast enhancement percentage 22.7%). Enhancement of the extra‐ocular muscles persisted 10 min after contrast administration (median contrast enhancement percentage 43.4%). Findings indicated that MRI contrast enhancement of extra‐ocular muscles is likely normal in dogs.     

Intraobserver and interobserver repeatability of ocular biometric measurements obtained by means of B-mode ultrasonography in dogs

OBJECTIVE: To assess intra- and interobserver repeatability of ocular biometric measurements obtained by means of high-resolution B-mode ultrasonography in dogs. Animals-6 Beagles without ocular abnormalities. PROCEDURES: B-mode ultrasonography was performed bilaterally with a 10.5-MHz broadband compact linear array transducer. All measurements were made on 2 different occasions by 2 observers. The Bland-Altman method was used to assess agreement between measurements obtained by the 2 observers and between the 2 sets of measurements obtained by each observer. RESULTS: Intra- and interobserver repeatability was highest for larger measurements, such as depth of the eye and depth of the anterior chamber. When repeatability was examined, bias was significantly different from 0 for only a few measurements, but the percentage difference between observations was as high as 180% for some measurements. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that most measurements of intraocular distances and structures obtained by means of high-resolution B-mode ultrasonography have acceptable intra- and interobserver repeatability. However, the percentage difference between observations can be high for smaller measurements.     

Persistent hyperplastic tunica vasculosa lentis and persistent hyaloid artery in a 2-year-old basset hound.

A 2-year-old Basset hound with unilateral persistent hyperplastic tunica vasculosa lentis and primary vitreous is described. There was leukokoria in the left eye, caused by bluish-white polar densities and haemorrhagic discoloration in the nucleus of the lens. Ultrasonographic examination of the eye revealed a small hyperechoic lens and a hyperechoic linear soft-tissue strand extending from the posterior pole of the lens through the optic disc. Power Doppler imaging revealed blood flow in this persistent hyaloid artery, but 5 months later, immediately prior to surgery, there was no flow in this artery. Ultrasonography, including Power Doppler imaging, was useful to confirm the diagnosis and to estimate the complications of surgery, especially the risk of vitreal haemorrhage after cutting of the persistent hyaloid artery. Comparison of the ultrasonographic images with those obtained by computed tomography suggested that the resolution of computed tomography is inadequate for identifying structures as fine as a persistent hyaloid artery.     

ULTRASONOGRAPHIC EVALUATION OF PRE- AND POSTNATAL DEVELOPMENT OF THE EYES IN BEAGLES

Transabdominal ultrasonography was performed to visualize the development of intraocular structures of both eyes of four different fetuses in each of two pregnant beagles. Postnatally the development of both eyes of 11 pups was visualized with ultrasonography. Furthermore, biometric measurements of the length of the eye, the depth of cornea, the anterior chamber, the lens (anteroposterior depth and equatorial diameter), and the vitreous body of the fetuses and pups were obtained when these structures could be identified with ultrasonography. In all fetuses the eyes with lens, vitreous body, hyaloid artery, and scleroretinal rim could be clearly identified from day 37 of pregnancy. Postnatally also the cornea, anterior chamber, iris, ciliary body, and optic disc were visible. Biometric measurements revealed, both pre- and postnatally, a continuous growth of the depth of the eye, anterior chamber, lens (anteroposterior depth and equatorial diameter), and vitreous body.     

ULTRASONOGRAPHIC DIAGNOSIS OF PERSISTENT HYPERPLASTIC TUNICA VASCULOSA LENTIS/PERSISTENT HYPERPLASTIC PRIMARY VITREOUS IN TWO DOGS

Ultrasonography was performed on a Basset hound and a Doberman clinically suspected of persistent hyperplastic tunica vasculosa lentis/persistent hyperplastic primary vitreous. In both dogs, hyperechoic lenses with a triangular-shaped echodense structure retrolentally were visible, and a very thin hyperechoic strand was seen penetrating the anechoic vitreous from this retrolental tissue to the area of the optic nerve. Using color Doppler imaging, blood flow was evident in parts of the retina in both dogs. With power Doppler imaging there was blood flow in the lens and hyperechoic strand of the Basset hound on the first examination; whereas, on re-examination 5 months later, this was not found. Other abnormalities, such as retinal detachment, endophthalmitis, vitreous hemorrhage, microphthalmia, and posterior neoplasia could be excluded.     

Climate variability during the past 2,000 years and past economic and irrigation activities in the Aral Sea basin

The lake level history, here based on the relative abundance of Ca (gypsum), is used for tracing past hydrological conditions in Central Asia. Lake level was close to a minimum before approximately a.d. 300, at about a.d. 600, a.d. 1220, a.d. 1400 and since 1960s it is lowering again. Lake water level was lowest during the fourteenth or early fifteenth centuries as indicated by a coeval settlement, which today is still under water near the well-dated mausoleum of Kerderi. Pollen data from riparian vegetation indicate generally wet conditions between a.d. 400 and a.d. 900, intermitted by short intervals with drier conditions (AD 550–600; a.d. 650–700) and riverbanks were again dry from a.d. 900–1150, a.d. 1450–1550, and from a.d. 1970 onward moisture decreased steadily. Irrigation activities were at a maximum between 300 b.c. and a.d. 300 (Classical Antiquity) and between a.d. 800 and a.d. 1300 (Medieval Age) and after a.d. 1960.