Morphological investigations on the circulus arteriosus cerebri in mole-rats (Spalax leucodon)

The aim of the present study is to investigate the circulus arteriosus cerebri in mole-rats (Spalax leucodon). Six adult mole-rats were used for this purpose. Coloured latex was injected into the left ventriculus of the hearts of all the animals. After careful dissection, the circulus arteriosus cerebri (the circle of Willis) was investigated. The cerebrum and the cerebellum were supplied by the internal carotid- and the basilar arteries respectively forming the circulus arteriosus cerebri in mole-rats. In the investigated objects, the internal carotid- and the basilar arteries were not united directly and for this reason the circulus arteriosus cerebri was not formed completely in mole-rat. The branches supplying the medulla oblongata and the cerebellum originate from the basilar artery formed by union of the left and right vertebral arteries and the internal ophthalmic, the caudal cerebral, the choroid, the median cerebral, the rostral cerebral arteries originated from the internal carotid artery. After giving off the medial cerebral artery, the right and left rostral cerebral arteries on every two sides divided into the lateral and medial twin branches and by union of the lateral branches the internal ethmoidal artery, and by union of the medial branches, the ramus extending to facies medialis cerebri were formed. The ramus extending to the facies medialis cerebri was anastomosed with the branch of the caudal cerebral artery on the back of the corpus callosum. The last part of the basilar artery gave the two branches running toward the right and left side on the pontocrural groove (sulcus pontocruralis) and every one of these branches ramified into two rami. One of these rami formed into the rostral cerebellar artery and the other one extended to the tectum mesencephali. In conclusion, the arterial circle of the cerebrum and cerebellum was supplied by the internal carotid artery and the basilar artery respectively in mole-rats.     

Morphology and comparative anatomy of circulus arteriosus cerebri in mammals

The normal configuration of the arterial pattern at the base of the brain in rhesus monkeys, dogs, sheep, goats and rabbits is described. The length and diameter of all vessels of the circulus arteriosus cerebri are measured. Variations are compared in relation to that of the typical pattern present in humans. In rhesus monkeys, dogs and rabbits, the circle of Willis is almost similar to that in human beings except that in these animals, (i) the anterior cerebral arteries join each other to form a single median vessel; (ii) in dogs, rabbits, goats and sheep the anterior cerebellar artery is a branch of posterior cerebral artery, and (iii) in goats and sheep, a considerable length of the internal carotid artery contributes to the formation of circulus arteriosus while the posterior cerebral artery arises from the posterior communicating artery.     

INFLUENCE OF FIELD STRENGTH ON INTRACRANIAL VESSEL CONSPICUITY IN CANINE MAGNETIC RESONANCE ANGIOGRAPHY

Eight neurologically normal beagles were imaged using three-dimensional (3D) time-of-flight magnetic resonance angiography (MRA) in a 3 T magnetic resonance scanner. Four of the eight dogs were also imaged using a 1 T unit for comparison. Ten intracranial arteries were consistently identified at 3 T: external and internal carotid, basilar, vertebral, rostral cerebral, middle cerebral, caudal cerebral, rostral communicating, caudal communicating, and ventral spinal arteries. Only four were reliably identified at 1 T with diagnostic spatial and contrast resolution. At 3 T, vessels as small as 1 mm were reliably detected. Vessel conspicuity was superior using the 3 T system. An anatomic atlas of the canine circulus arteriosus cerebri using a 3 T scan was constructed. The effect of MRA parameters on vascular spatial resolution and conspicuity are reviewed.     

A quantitative study of the circulus arteriosus cerebri of the camel (Camelus dromedarius)

The afferent vessels of the circulus arteriosus cerebri in the camel were studied quantitatively. It was found that the diameters of the arteries did not differ significantly on the left and right sides. An interesting observation was that the basilar artery contributed to the blood supply of the brain in the camel, in contrast to the situation in other ruminants.     

IMAGING DIAGNOSIS: AZYGOUS CONTINUATION OF THE CAUDAL VENA CAVA WITH AND WITHOUT PORTOCAVAL SHUNTING

The CT angiographic features of azygous continuation of an interrupted caudal vena cava in dogs with and without portocaval shunting are described. Azygous continuation of a discontinuous caudal vena cava is usually an incidental finding, not associated with portosystemic shunting. Identification of an associated portosystemic shunt will determine the need for surgical intervention. CT angiography provides a means for making this distinction and details the course and size of the anomalous vessels. Focal widening of the caudal vena cava on a VD thoracic radiograph should raise suspicion for azygous vein distension.     

Congenital cardiac disease in dogs

Thoracic conformation, age, amount of body fat, and stage of respiration and cardiac contraction affect the cardiac silhouette. Deep-chested dogs have an upright, narrow cardiac silhouette about 2 1/2 intercostal spaces wide, while barrel-chested dogs have a round, wide silhouette about 3 1/2 intercostal spaces wide. On LAT films the vessels to a lung lobe should be of equal size and 0.25-1.2 times the diameter of the upper third of the 4th rib at the 4th intercostal space. On DV projections, vessels to the caudal lung lobe should be no larger than the diameter of the 9th rib. Signs of right ventricular enlargement include loss of the cranial waist, increased width of the cardiac silhouette, increased sternal contact of the heart, and an elevated cardiac apex. Signs of left ventricular enlargement include an elevated carina, loss of the caudal waist, and a more perpendicular caudal cardiac border. Signs of left atrial enlargement include separation of mainstem bronchi, compression of the bronchus to the left caudal lung lobe, and an increased distance from the carina to the dorsal border of the caudal vena cava. Enlargement of the aorta and main pulmonary artery segment on a LAT view appears as a soft tissue density obscuring the cranial waist. Pulmonary vascular fields are usually hypervascular in patent ductus arteriosus and interventricular septal defects, normal in uncomplicated aortic or pulmonic stenosis, and hypovascular in tetralogy of Fallot.     

Use of sodium nitroprusside in the anaesthetic protocol of a patent ductus arteriosus ligation in a dog

Patent ductus arteriosus (PDA) is one of the most common congenital cardiac abnormalities in the dog. Sodium nitroprusside has been proposed as an infusion during PDA ligation as the resultant nitric oxide production causes hypotension thereby facilitating surgical dissection and decreasing the risk of haemorrhage. This case report details how the method described did not decrease blood pressure and therefore had no beneficial effects. It is speculated that the lack of response may have been due to tachyphylaxis. Other drugs may be preferred to induce deliberate hypotension in the dog.     

Radiographic retrospective study of the caudal cervical articular process joints in the horse

Reasons for performing study: Arthropathy of the caudal cervical articular process joints (APJs) in the horse is documented as a cause of ataxia and paresis secondary to spinal cord compression. Enlargement of the caudal APJs is reported to increase with age, but there are no known associations of any other factors. No association of the degree of APJ enlargement with neurological signs seen has been documented. This study investigated the associations of cervical APJ enlargement at the C5‐C6 and C6‐C7 articulations with case subject details (breed, age, sex, usage) and clinical signs. Objectives: To ascertain if there are of any associations between: the subject details and enlargement of the caudal cervical APJs; and the degree of APJ enlargement and the presence and type of clinical signs. Hypotheses: There would be an effect of age, breed and usage on APJ grade, with no effect of sex. Association between grade and clinical signs seen was also investigated. Materials and methods: The radiographs of 122 horses qualified for inclusion. Horses were excluded if they were known to have a neck lesion cranial to C5‐C6, or if the radiographs were rotated or of poor quality. In order to standardise the interpretation of APJ enlargement, a novel grading system was developed and used. Results: An association was found between age and APJ grade at C5‐C6 but not C6‐C7. There was no association between grade, breed, sex and usage, or clinical signs seen. Data also showed a trend for increasing enlargement the more caudal the APJ. Conclusion and potential relevance: The data in this study support that the size of the caudal cervical APJ at the level of C5‐C6, appear to increase with age, but this enlargement may not be significant. Enlargement cannot be associated with breed, sex or discipline of the horse at present, and specific grades and therefore degree of enlargement, cannot necessarily be assumed to be the cause of neurological deficits.     

Pseudo truncus arteriosus in a dog—a case report

The clinical, electrocardiographic, angiographic, radiological and postmortem features of a case of pseudo truncus arteriosus in an 8-month-old crossbred Labrador puppy are described.     

Congenital cardiac disease in dogs

Patent ductus arteriosus (PDA) is thought to be inherited and occurs twice as often in females as in males, most commonly in Poodles, Collies, Cocker Spaniels and Shetland Sheepdogs. About half of untreated dogs develop left-sided heart failure by 8 months of age. Clinical signs include coughing, decreased exercise tolerance, pulmonary edema, a "machinery" murmur in the pulmonic-aortic region, and a bounding pulse. An ECG may reveal an increased amplitude of the R wave and a lengthened P wave. Plain LAT films reveal loss of the cranial and caudal cardiac waists, increased sternal contact of the heart, increased width and straightened caudal border of the cardiac silhouette, elevated carina, and an enlarged left atrium. Changes on plain DV films include an elongated cardiac silhouette, enlarged right ventricle, and 3 bulges on the left side of the cardiac silhouette. Nonselective angiocardiography can be used for a definitive diagnosis and to demonstrate a reverse right-to-left PDA, in which the ascending aorta, brachiocephalic trunk and left subclavian artery are not opacified by contrast medium. Animals with a right-to-left shunt PDA are cyanotic in caudal body parts. Treatment of left-to-right shunt PDA involves ligation with 2 nonabsorbable sutures. A right-to-left shunt PDA should not be ligated but is treated by restricted exercise and periodic phlebotomy.     

Patent ductus arteriosus in Murrah buffalos

Two cases of patent ductus arteriosus are described in 2 Murrah buffalos, a 7.5-month-old heifer calf and a 5-month-old bull calf. The main clinical signs consisted of exercise intolerance, dyspnea, and tachycardia. At necropsy, lesions were consistent with congestive heart failure as indicated by dependent subcutaneous edema, body cavity effusions, and nutmeg liver. The lungs were extensively atelectatic. The heart was enlarged and had a globous shape. The ductus arteriosus, measuring 0.8 cm in length and 0.4 cm in caliber, was patent. The proximal pulmonary artery had an approximately 50-mm-long aneurysm. Eccentric cardiac hypertrophy was evident primarily in the right but to a lesser degree also in the left ventricle. Additionally, there was diffuse subendocardial fibrosis in the left and right ventricle. To the best of the authors' knowledge, patent ductus arteriosus was not previously described in buffalos. Since both calves were sired by the same bull, it is possible that this cardiac anomaly has a hereditary basis.     

Extrinsic Cardiac Nerve Distribution in Goitred Gazelle (<Emphasis Type="Italic">Gazella subgutturosa</Emphasis>)

Extrinsic cardiac nerves and their patterns are described based on anatomical dissections of five goitred gazelle. Sympathetic cardiac innervation was mainly provided by the cervicothoracic and thoracic cardiac nerves. No left caudal cervicothoracic nerves, middle cervical cardiac nerves and vertebral cardiac nerves from the vertebral ganglion were observed. Parasympathetic cardiac innervation was supplied by the nerve fibres from the caudal vagal cardiac rami only. No cardiac rami from the cranial vagal cardiac nerves present in small ruminants were observed in this study. The caudal laryngeal and phrenic cardiac nerves also contributed to the cardiac innervation.     

Primary intestinal lymphangiectasia in three dogs: a morphological and immunopathological investigation

Morphological and immunological findings of three dogs with primary lymphangiectasia are described and compared with three normal dogs. Scanning electron microscopy showed distended and fused intestinal villi in dogs with intestinal lymphangiectasia, and morphometric evaluation revealed deeper crypts in the small intestine of dogs with intestinal lymphangiectasia. Although plasma cells of all classes were diminished in the cranial parts of the small intestine, there was an absolute and relative increase of immunoglobulin G-containing plasma cells in the caudal small intestine in dogs with intestinal lymphangiectasia.     

Surgery of the scrotum.

Scrotal surgery is common in routine veterinary practice. Many techniques are available for commonly performed surgeries, and most can be accomplished easily in private practice and in the field. Procedures are described for surgical and nonsurgical castration, unilateral castration, inguinal herniorrhaphy, cryptorchidectomy, caudal epididymectomy, and vasectomy. Changes in current thinking about the timing of castration and about pain control in cattle surgery likely will alter the way veterinarians perform scrotal surgery in the years to come.     

Prenatal development of the caudal vena cava in mammals: review of the different theories with special reference to the dog

Several items of the development of the caudal vena cava in domestic animals are still controversial. In particular, the origin of the lumbar segment of the caudal vena cava is equivocally described. According to different theories it originates from the right-sided supracardinal, caudal cardinal, sacrocardinal, lateral sympathetic or subcardinal veins. In this review, all five theories are compared with each other and discussed in the light of anatomical variations observed in eight dogs. Species-specific diversity, erratic observations because of technical artefacts, and biased interpretation of the original data are three major reasons for the dissimilarity between the five theories, but they cannot explain all differences. Further studies by using modern techniques such as microvascular corrosion casting and non-invasive three-dimensional microtomography are necessary to better understand the normal development and to explain the variations in domestic animal species.     

IMAGING DIAGNOSIS—ULTRASONOGRAPHIC DIAGNOSIS OF DIPLOMYELIA IN A CALF

We describe the ultrasonographic diagnosis of diplomyelia in a 40‐day‐old calf. The acoustic window was the lumbosacral junction, which, in cattle, corresponds to the L6–S1 intervertebral space and enables the evaluation of approximately 1 cm of the length of the spinal cord. Despite this limited length, this acoustic window yields good anatomic details and can be helpful in assessing anomalies of the caudal aspect of the spinal cord.     

Estudio anatómico y estructural del bulbo ocular del ratonero común (Buteo buteo buteo)

The Bulbus oculi of 25 buzzards of both sexes and of nearly the same age and weight, was examined with regard to its gross anatomy, strucutre, ultrastructure and size. The volume of the eyeball is of 9.5 cm³. In the Anulus sclerae there are about a dozen of cartilagineous plates, and in the Corpus ciliare there can be found between 112 and 115 Processus ciliares. The muscle of Müller was not observed. Morphological details of the Pecten are given and its functional significance is discussed.     

Computed tomographic and magnetic resonance imaging features of canine segmental caudal vena cava aplasia

O bjective : To describe the computed tomographic and magnetic resonance imaging features of segmental caudal vena cava aplasia and associated vascular anomalies in dogs.
M ethods : A retrospective study was performed reviewing computed tomographic and magnetic resonance imaging archives of eight institutions for dogs with segmental caudal vena cava aplasia. Inclusion criteria included a computed tomographic or magnetic resonance imaging study and supportive diagnostic and follow-up information. Abdominal vessels were reviewed for size, shape, location and course (including tributaries and branches) and classified as normal, abnormal or shunt vessels.
R esults : Ten dogs with segmental caudal vena cava aplasia were identified. In all dogs, postrenal caval blood was shunted to either a right or a left azygos vein, with seven different angiographic patterns. Affected dogs were predominantly female (70 per cent) and young (mean 2·6 years). Additional portocaval and porto-azygos shunt vessels were identified in two cases each. Computed tomographic angiography and magnetic resonance angiography depicted details of abdominal vessels including thrombus formation in one dog.
C linical S ignificance : Segmental caudal vena cava aplasia is a vascular congenital anomaly in the dog that can be associated with thrombosis and portosystemic shunts. Computed tomographic angiography and magnetic resonance angiography are excellent tools to demonstrate the complex vascular anatomy and to guide treatment planning for portosystemic shunts and thrombolytic therapy.     

Esophageal obstruction caused by a left aortic arch and an anomalous right patent ductus arteriosus in two German Shepherd littermates

OBJECTIVE: To present details of surgical management of an unusual vascular ring anomaly in two German Shepherd littermates. STUDY DESIGN: Clinical case report. STUDY POPULATION: Three-month-old intact male and female German Shepherd littermates. RESULTS: In each dog, the esophagus was obstructed by a vascular ring comprised of the left aortic arch, an anomalous patent right ductus arteriosus, and the pulmonary artery ventrally. Surgical treatment consisted of dividing and oversewing the patent right ductus arteriosus. Neither dog has clinical signs of esophageal disease one year after treatment. CONCLUSION AND CLINICAL RELEVANCE: This vascular ring anomaly should be considered a possibility in any young dog with esophageal obstruction and a machinery murmur.     

Magnetic resonance imaging findings of an intracranial medulloblastoma in a Polish Lowland Sheepdog

Medullobastoma is an uncommon caudal fossa tumor. The imaging features of medullobastoma in the dog are poorly described. In this report, the magnetic resonance (MR) appearance of a cerebellar medullobastoma in a dog is described. The MR features were similar to medulloblastomas in adult humans, with the tumor arising laterally and extending to the surface of the cerebellar hemisphere. Correct localization of medulloblastoma may be difficult and it should be considered as a differential for both extra- and intra-axial caudal fossa masses.