A.M. Dickie

Comparison of ultrasonography, radiography and a single computed tomography slice for the identification of fluid within the canine tympanic bulla.

Fluid accumulation within the tympanic bulla (TB) is an important diagnostic indicator in clinical cases of canine otitis media although its identification can be a challenge using currently available imaging techniques. The aim of this study was to compare ultrasound with radiography and a single computed tomography (CT) slice for the identification of fluid within the TB of canine cadavers. A random number of TB in 66 cadavers were filled with ultrasound gel. Rostrocaudal open mouth (RCdoM) radiographs and CT images were interpreted by 2 blinded radiologists and ultrasound examinations were performed by 2 blinded sonographers. The heads were then frozen and sectioned to confirm the contents of each TB. Although CT remained the most accurate method, comparable results were obtained by one of the sonographers and even the inexperienced sonographer produced results superior to radiography. Ultrasound has several advantages over the other imaging techniques and this study suggests that it may have an application in the investigation of canine otitis media although further work in live animals would be required to confirm this.

Ultrasound imaging of the canine tympanic bulla

A procedure for imaging the canine tympanic bulla, external ear canal and adjacent structures using currently available ultrasound equipment was established. Lateral and ventral transducer positions were identified for this purpose and a 6.5 MHz curvilinear transducer was considered to be optimal. The sonographic appearance of these structures in cadavers and live dogs unaffected by ear disease is documented. Fluid was introduced into the tympanic bullae of the cadavers and its presence could be identified through the bony wall of the bulla. The ability of ultrasound to differentiate between gas and fluid within the bulla has important clinical implications as this is a common occurrence in dogs with middle ear disease. Ultrasound has several advantages over other imaging modalities and the examination procedure was well tolerated by unsedated dogs.

Ultrasonographic assessment of the rate of solid-phase gastric emptying in dogs

Twelve healthy dogs were used in an ultrasonographic assessment of the effect of the composition of a solid meal on the rate of gastric emptying. The dogs were fasted for nine hours before they were fed either a standard or a high energy density test meal, in a cross-over study design. The gastric antrum was visualised with a 6·5 MHz microconvex transducer, and the area inside the elliptical shape defined by the craniocaudal and ventrodorsal diameters of the stomach was measured. Antral images were acquired at regular intervals for six hours after the ingestion of the test meal. Three indices to describe the rate of gastric emptying were computed: the gastric half-emptying time (t1/2), the time to 50 per cent maximal antral area (t50%), and the time of maximal antral area (tmax). The values of t50% and t1/2 calculated for the high energy density meals were significantly longer than for the standard meals, but there was no significant difference between the tmax values.