BACKGROUND: The foramen magnum (FM) is an important landmark of the skull base and a transition zone between spine and skull as well as its close relationship to the brain and the spinal cord. So the FM has gained considerable interest due to its comparative anatomy, ontogeny, clinical, and animal breeding viewpoints. OBJECTIVES: The aim of this study was to determine morphology and morphometry of the occipital area of 20 mature and immature male Khouzestan river buffaloes. METHODS: 7 parameters of the occipital area and the shape of the FM in the skull of 20 mature and immature male Khouzestan river buffaloes were analyzed. RESULTS: The FM had 4 shapes including round, egg, oval, and tetragonal. In the mature and immature groups, the highest frequency of the FM shape belonged to oval. In the mature and immature groups, the tetragonal FM shape and the oval FM shape had the lowest frequency, respectively. The mean of the width, the length of the FM and the index of the FM in mature group was 38.60± 2.70, 35.34± 2.33, and 92.26±26 mm, respectively and 40.67± 1.51, 36.35± 2.33, and 90.23±3.65 mm in immature group, respectively. Amongst of the all parameters, the width and the length of the jugular process only differed significantly between mature and immature groups. CONCLUSIONS: The variations of the FM shape in river buffalo were more than those of reported animals. The  mean of  the length and  the width of  the FM,  the jugular processes width,  the length of the jugular process, the length  and width  of the  occipital condyles of male river buffaloes were greater than those of reported animals. The index of the FM in river buffalo was less than 100, which corresponded with the findings in rabbit, German shepherd and Pekingese dogs.

The size and shape of the foramen magnum were studied in skulls from 75 adult and 5 juvenile Pekingese dogs. After maceration of the skulls, the height, width, and area of each foramen magnum were measured, and various skull indices were determined. The shape of the foramen varied from ovoid to rectangular and had a dorsal notch in aU but 2 skulls. Prolapse of cerebellum or brain stem through the enlarged opening was prevented by a fibrous membrane covering he dorsal notch. Mean +/- SD area of the foramen was 138.1 +/- 26.1 mm(2); its mean total height was 15.0 +/- 2.9 mm, and its mean maximal width was 13.3 +/- 1.1 mm. Statistically, variability in the area of the foramen was mainly correlated with total height of the foramen, including the dorsal notch. Total height of the foramen was not correlated with age or gender. The degree of dysplasia, notch index, and occipital index of each foramen magnum were determined. To allow a more accurate evaluation of the morphology of the foramen, the foramen magnum index, defined as the ratio between the maximal width and the total height of the foramen, was also computed. Mean +/- SD foramen magnum index was 91.8 +/- 17.1 in the adult Pekingese dogs. Foramen magnum index was not significantly correlated with age, but was significantly larger in male than in female dogs. The large variability in the shape and size of the foramen magnum and the absence of any neurologic problems in dogs of this study indicate that the dorsal notch of the foramen magnum in brachycephalic dogs is a normal morphologic variation, rather than a pathologic condition.

Subgaleal hematomas are accumulation of blood between periosteum and galea aponeurosis. A 2-year-old male Chihuahua was presented with a severe head swelling after trauma. Radiography and computed tomography (CT) showed a massive swelling encircling the entire calvarial vault, extending toward the cervical neck and crossing the suture line. It was heterogeneously, mild hyperdense fluid to soft tissue attenuating with contrast enhancement on CT images. On day 4, physical and imaging examination showed resolution of the calvarial swelling. Subgaleal hematoma should be considered as a differential diagnosis when there is a massive soft tissue swelling over the skull on physical and imaging examinations.

Ten adult rabbit (5male and 5 female ) were used for gross anatomical and biometrical studies .The main characteristics feature of the local rabbit skulls are : in dorsal surface there are a shallow external sagittle crest , the frontal bone has anterior and posterior supraorbital process , the external acoustic meatus is a short wide bony tube directed caudodorsally , the orbita are large , the external surface of the maxilla is pitted by numerous small opening (fenestrated). A total of 16 linear measurement estimated in the rabbit skulls .There are significant difference between males and females observed in bizygomatic distance , basion-bragma height , maxilla- alveolar length , orbital height and foramen magnum breadth

Objective: To evaluate the use of high-resolution MRI for hippocampal volumetry in dogs and to define a lower reference limit for hippocampal formation (HF) volume. Animals: 20 dogs (with no history of seizures and no underlying structural brain disease) that underwent MRI of the brain. Procedures: The MRI protocol included a high-resolution T1-weighted 3-D ultrafast gradient-echo sequence aligned in a dorsal plane perpendicular to the long axis of the HF. Images obtained with MRI were retrospectively analyzed by 2 observers (A and B). Intraobserver and interobserver agreement were calculated with the Lin concordance correlation coefficient. Volume measurements of the HF were adjusted for intracranial volume, and a lower 95% reference limit for adjusted HF volume was calculated. Results: There was substantial intraobserver agreement (Lin concordance correlation coefficient, 0.97 [95% confidence interval {CI}, 0.94 to 0.99]) but poor interobserver agreement (Lin concordance correlation coefficient, 0.63 [95% CI, 0.37 to 0.79]). The lower 95% reference limit for adjusted HF volume was 0.56 cm3 (90% CI, 0.52 to 0.60 cm3) for the right HF and 0.55 cm3 (90% CI, 0.52 to 0.58 cm3) for the left HF. Conclusions and Clinical Relevance: HF volumes should be adjusted for intracranial volume to account for the large variation in canine skull size. The amount of time required to perform HF volumetry and low interobserver agreement may restrict this technique to research applications, such as the investigation of epileptic patients for hippocampal sclerosis or other cognitive disorders.

A technique for measuring upper airway resistance was developed in awake untrained dolichocephalic and mesaticephalic dogs. Twenty healthy dogs, 10 Collies (group dolichocehalic) and 10 mixed-breed dogs (group B-mesaticephalic), were studied. All dogs tolerated the procedure well and adverse effects were not observed. Mean (+/- SEM) value for upper airway resistance was 7.1 +/- 0.50 cm of H2O/L/s. There was a trend toward lower upper airway resistance (Ruaw) values in group-A dogs, compared with those in group-B dogs. Values of Ruaw were reproducible for an individual dog. The mean individual dog coefficient of variation for Ruaw was 7.5%. The overall Ruaw coefficient of variation for all 20 dogs was 31.4%. This technique for measuring upper airway resistance in dogs is clinically applicable for objectively assessing response to treatment of obstructive upper airway disorders.

OBJECTIVE To evaluate with CT the characteristics of brain tissue disruption and skull damage in cadaveric heads of adult horses caused by each of 6 firearm-ammunition combinations applied at a novel anatomic aiming point. SAMPLE 53 equine cadaveric heads. PROCEDURES Heads placed to simulate that of a standing horse were shot with 1 of 6 firearm-ammunition combinations applied at an aiming point along the external sagittal crest of the head where the 2 temporalis muscles form an inverted V. Firearm-ammunition combinations investigated included a .22-caliber long rifle pistol firing a 40-grain, plated lead, solid-core or hollow-point bullet (HPB); a semiautomatic 9-mm pistol firing a 115-grain, jacketed HPB; a semiautomatic .223-caliber carbine firing a 55-grain, jacketed HPB; a semiautomatic .45-caliber automatic Colt pistol firing a 230-grain, jacketed HPB; and a 12-gauge shotgun firing a 1-oz rifled slug. Additional heads placed in a simulated laterally recumbent position were shot with the semiautomatic 9-mm pistol–HPB combination. All heads underwent CT before and after being shot, and images were evaluated for projectile fragmentation, skull fracture, and cerebrum, cerebellum, and brainstem disruption. RESULTS Computed tomography revealed that all firearm-ammunition combinations caused disruption of the cerebrum, cerebellum, and brainstem that appeared sufficient to result in instantaneous death of a live horse. Hollow-point ammunition was as effective as solid-core ammunition with regard to brain tissue disruption. Brain tissue disruption was not affected by head positioning. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that the examined firearm-ammunition combinations, when applied at a novel aiming point, appear to be reasonable options for euthanasia of horses.