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.

Canine brachycephalic obstructive airway syndrome (BOAS) is a conformation-related respiratory disorder of dog breeds having congenitally flattened facial and skull anatomy. The aim of the study was to determine oxidative stress parameters, the lipid peroxidation product malondialdehyde, and antioxidant enzymes superoxide dismutase (SOD) and glutathione peroxidase in BOAS patients before and after surgical treatment and in healthy brachycephalic dogs. Nine healthy brachycephalic dogs that had not undergone surgery and 39 BOAS patients were included in the study. The BOAS patients were classified as grade 1 (5/34), grade 2 (16/34), and grade 3 (13/34) based on the decrease in the radius of the airway in the larynx. In BOAS patients, oxidative stress parameters were determined before and two weeks after surgery, while in control dogs, blood samples were collected only on inclusion to the study. All BOAS patients showed various degrees of improvement in clinical signs after surgery. Significantly lower (P < 0.05) SOD activity was found in grade 2 and 3 BOAS patients than in grade 1 patients. Two weeks after surgery, a significant (P < 0.05) increase in SOD activity in grade 2 and 3 patients was observed. Antioxidant enzyme SOD may play an important role in BOAS and can be used as a biomarker of antioxidant status assessment in BOAS patients.

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.

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 surgical technique was developed for implanting a flexible polyurethane cannula in a lateral ventricle in the brain of calves. Initially, measurements were made on 25 calves at necropsy to develop equations for calculating coordinates for cannula placement. The distance (cm) caudal, in the sagittal plane, from the coronal suture line to the center of a hole to be drilled in the parietal bone of the skull was: 0.73 + (0.00925 X body weight [kg]). The distance (cm) lateral from the midline to the center of the hole to be drilled was: 0.018 + (0.6464 X distance caudal). The depth (cm) from the surface of the skull to the dorsal surface of the lateral ventricle was: 2.29 + (0.0159 X body weight [kg]). Surgery was subsequently performed on 17 calves. A 5-mm-diameter hole was drilled through the skull with a hand trephine at coordinates derived from the aforementioned regression equations. A polyurethane cannula (total length, 30 cm; 1 mm ID; 2 mm OD) covering a stainless-steel 20-gauge blunt-tipped needle (stylet) was lowered through the brain and into a lateral ventricle at an angle of 20.5 degrees relative to the frontal bones of the skull. The blunt-tipped needle was then removed, and CSF was allowed to drip from the cannula to verify placement. One stainless-steel screw was inserted 0.6 cm medial, and another was inserted 0.6 cm caudal to the hole in the skull. The area around the cannula, bone screws, and hole in the skull was covered with dental acrylic (approx 2 cm in diameter) to stabilize the cannula. With minimal restraint of calves, injection of substances into and withdrawal of CSF from a lateral ventricle of the brain were possible in most calves for at least 6 weeks after surgery was performed.

OBJECTIVE To assess the extent of damage to the skull and brain of cadaveric dairy goat kids caused by a .22-caliber, 16-g pellet fired from a multipump air pistol at various power levels. SAMPLE Cadavers of 8 male and 7 female dairy goat kids ≤ 5 days old. PROCEDURES Each cadaver was positioned in sternal recumbency with the head and neck extended on a straw bale. A multipump air pistol was held with the barrel perpendicular to and 2.5 cm from the head at the intersection of 2 imaginary lines that extended from the lateral canthus of each eye to the middle of the contralateral ear base and fired at half (5 pumps; n = 2), intermediate (7 pumps; 2), or full (10 pumps; 11) power. The head and neck were removed from the carcass for CT imaging and gross sectioning to determine the location of the pellet and extent of damage caused to the skull and brain. RESULTS The pellet successfully penetrated the skull of all 13 heads shot at full or intermediate power and 1 of the 2 heads shot at half power. The pellet did not fragment after entering the skull of any cadaver and penetrated the brainstem (necessary for instantaneous death) in only 7 cadavers. CONCLUSIONS AND CLINICAL RELEVANCE The described technique was insufficient for use as a stand-alone method for euthanizing young dairy goat kids. Modification of the technique warrants further research to determine whether air pistols can be used to effectively euthanize young goat kids.

OBJECTIVE To use MRI and CT to compare the amount of tissue damage (soft tissue and bone) to the heads of goats after administration of a nonpenetrating or penetrating captive bolt. ANIMALS Cadavers of twelve 1- to 5-year-old mixed-breed goats that had been euthanized with an overdose of pentobarbital as part of an unrelated study. PROCEDURES Cadavers were randomly assigned to receive a nonpenetrating (n = 6) or penetrating (6) captive bolt. The head of 1 cadaver was imaged via CT and MRI. The muzzle of a device designed to administer either a penetrating or nonpenetrating captive bolt was then placed flush on the dorsal midline of each head at the level of the external occipital protuberance (poll) and aimed downward toward the cranialmost portion of the intermandibular space, and the assigned bolt was administered. Heads were removed, and CT and MRI of each head were performed. After imaging, each skull was transected along the sagittal plane to permit gross evaluation of central nervous tissue and obtain digital photographic images. In addition, 1 head that received a nonpenetrating captive bolt was further evaluated via blunt dissection and removal of adnexa from the external surface of the calvarium. RESULTS MRI, CT, and dissection of skulls revealed severe skeletal and soft tissue damage after impact with the penetrating and nonpenetrating captive bolts. CONCLUSIONS AND CLINICAL RELEVANCE The nonpenetrating captive bolt appeared to cause damage similar to that of the penetrating captive bolt in the cranium and soft tissues of the head in caprine cadavers. This damage suggested that administration of a nonpenetrating captive bolt as described here may be an acceptable method of euthanasia in goats.

The maxillary sinus appeared first among the sinuses of the skull at 92 days of prenatal stage. The early formation of frontal sinus was observed at 157 days in the cranial most part of the frontal bone while the early formation of palatine sinus was observed at 170 days. A total of five fontanelles were observed in prenatal skulls of buffalo. The largest and unpaired fontanelle was anterior fontanelle. The mastoid and sphenoidal fontanelle were paired. The ossification of anterior fontanelle was first observed at 164 days. All the fontanelles were ossified completely prenatally.