Determination of corpora lutea numbers in Booroola--Texel ewes using transrectal ultrasound.

Ovulation rates in Booroola--Texel ewes are currently determined by laparoscopic examination of the ovaries during the luteal phase allowing for carrier status of the ewe to be diagnosed. However, this is an invasive procedure and the aim of this work was to determine whether or not transrectal ultrasound would be an acceptable and accurate alternative to laparoscopy for this purpose in ewes. Transrectal ultrasound was performed using a 5.0 MHz transducer in 18 ewes restrained in the standing position. They were then euthanized and laparoscopy was performed, following which the reproductive tracts were recovered. An additional 22 ewes were subjected to scanning in dorsal recumbency, using a 7.5 MHz transducer, at various stages of the luteal phase before being euthanized and the reproductive tracts recovered. The ovarian structures identified using each method were then compared. The results demonstrated that laparoscopy is an accurate method of determining ovulation rates in ewes. Transrectal ultrasound examination appeared to be an acceptable and non-invasive procedure. The use of a 7.5 MHz transducer with the ewes in dorsal recumbency produced the best results and clearest images of the ovaries, which allowed for the determination of the number of corpora lutea (CL) and the presence of other structures. Accuracy improved with experience in the technique, the stage of the luteal phase at which the examination was performed, the number of CL present in the ovary and the age of the ewe. Further work is needed to confirm this finding due to the small numbers of animals in the present study. This ultrasound technique, however, has the potential to provide an alternative to laparoscopy for the determination of numbers of CL in ewes.

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.

A review of methods for assessment of the rate of gastric emptying in the dog and cat: 1898-2002.

Gastric emptying is the process by which food is delivered to the small intestine at a rate and in a form that optimizes intestinal absorption of nutrients. The rate of gastric emptying is subject to alteration by physiological, pharmacological, and pathological conditions. Gastric emptying of solids is of greater clinical significance because disordered gastric emptying rarely is detectable in the liquid phase. Imaging techniques have the disadvantage of requiring restraint of the animal and access to expensive equipment. Radiographic methods require administration of test meals that are not similar to food. Scintigraphy is the gold standard method for assessment of gastric emptying but requires administration of a radioisotope. Magnetic resonance imaging has not yet been applied for assessment of gastric emptying in small animals. Ultrasonography is a potentially useful, but subjective, method for assessment of gastric emptying in dogs. Gastric tracer methods require insertion of gastric or intestinal cannulae and are rarely applied outside of the research laboratory. The paracetamol absorption test has been applied for assessment of liquid phase gastric emptying in the dog, but requires IV cannulation. The gastric emptying breath test is a noninvasive method for assessment of gastric emptying that has been applied in dogs and cats. This method can be carried out away from the veterinary hospital, but the effects of physiological and pathological abnormalities on the test are not known. Advances in technology will facilitate the development of reliable methods for assessment of gastric emptying in small animals.

The effect of obliquity on the radiographic appearance of the temporomandibular joint in dogs.

The temporomandibular joint is formed between the condyloid process of the mandible and the mandibular fossa of the temporal bone. The basic anatomy of this joint was assessed and described in a series of skulls including dolichocephalic, mesaticephalic and brachycephalic breeds. The facial index and rotational angles were measured with the facial index providing a useful method of classifying skull types but the rotational angle being of limited use in assessment of the temporomandibular joint until normal breed values are established. Equipment was designed to allow repeatable positioning of the temporomandibular joint for radiography at a variety of lateral and long axis rotational angles relative to the central x-ray beam. The regions of the joint and anatomic features visualized in each view are demonstrated. 10 degrees rotation was required in either axis to project the joints independently of each other. Lateral rotational angles of 10 to 30 degrees in mesaticephalic and dolichocephalic breeds and 20 to 30 degrees in brachycephalics and long axis rotational views of 10 to 30 degrees depending on the region of interest were considered to be the most useful.