横断山五个地区大绒鼠头骨的几何形态学研究

为探讨横断山不同地区大绒鼠头骨的形变特征,本研究选取5个采样地,自北向南依次为德钦、香格里拉、丽江、剑川和哀牢山,采用几何形态测量技术对5个采样地大绒鼠头骨的背面、侧面、腹面、下颌侧面和上下臼齿的形态进行了研究。结果表明:主成分分析和判别函数分析显示5个采样地的大绒鼠头骨背面仅哀牢山单独分开,其他4个地区混杂在一起;经过薄片样条法分析显示5个地区大绒鼠的头骨形变多集中在两个位置,分别为:鼻骨处和颧弓处;经多维尺度分析显示5个地区大绒鼠头骨和臼齿均有一定的差异,这可能与经纬度、海拔和气温等变化有关。总之,位于横断山区不同环境的大绒鼠头骨形态具有差异。     

Mandibular Osteodistraction for Correction of Deep Bite Class II Malocclusion in a Horse

Objective— To describe a technique for, and outcome after, mandibular osteodistraction in the horse.
Study Design— Clinical report.
Animals— Warmblood horse.
Methods— A half ring external fixator was applied on both sides of an osteotomy site performed on the mandible of a colt. A bite plate was placed on the upper incisors creating occlusion between lower and upper jaw. After a 5-day latency period, distraction was applied (1 mm/day) until the overjet was judged normal.
Results— Mandibular elongation and correction of brachygnathia was obtained without major complications. Six months after the procedure the overjet reduction was considered stable.
Conclusions— Mandibular osteodistraction can be considered for treatment of severe brachygnathia in yearlings.
Clinical Relevance— Distraction osteogenesis has the advantage of progressive elongation of the mandible, allowing concurrent bone remodeling and soft tissue adaptation. Severe mandibular incisor malocclusion in horses outside the maximal growth phase can be corrected using this technique.     

Life Threatening Complication Associated with Anesthesia in a Dog with Masticatory Muscle Myositis

Objective— To report a serious complication in a dog with masticatory muscle myositis (MMM) that occurred during general anesthesia for diagnostic testing.
Study Design— Case report.
Animals— A 2-year-old male Pug.
Methods— MMM was diagnosed in a Pug with a 2-week history of trismus by electrodiagnostics, histopathology, and 2M antibody test. During anesthesia tongue protrusion occurred and because of trismus, an inability to reposition the tongue resulted in venous congestion and severe swelling. Forceful physical attempts and subsequent removal of the rostral digastricus and masseter muscle attachments from the mandible did not increase jaw mobility. Mandibular symphysiotomy was necessary to resolve lingual venous congestion and to reposition the tongue into the oral cavity.
Results— Tongue swelling rapidly subsided after symphysiotomy allowing the tongue to be repositioned into the oral cavity. After treatment of MMM with corticosteroids, jaw range of motion improved and at 6 months was ∼70% normal.
Conclusions— Trismus could not be overcome by detachment of the masseter and digastricus muscle insertions from the mandible, and symphysiotomy was required to reposition the tongue in the oral cavity.  

Clinical Relevance—

In dogs with MMM, tongue position should be monitored during anesthesia to avoid inadvertent protrusion and swelling from venous congestion. Use of anesthetic monitoring equipment on the tongue, such as a pulse oximeter probe, should be avoided in these patients.     

A morphological study of skeletal development in turkeys during the pre-hatching stage

Skeletal chondrofication, ossification and growth of turkey embryos were investigated and analysed to enable assessment of the developmental status and evaluation of the experimental effects on skeletal development, skeletal mutations and development of cultured embryos. Ten embryos were prepared every 24 h from 8 to 28 days of incubation. The fixed embryos were cleared and stained in toto with Alcian blue & Alizarin red for cartilage and ossified components, respectively. Observation of the skeleton was performed under a stereoscopic microscopy, with special attention to the timing of chondrofication and ossification of the bones. The first occurrence of the primary ossification centres was observed in the femur, tibiotarsus, and the dentary and supra-angular of the mandible on the 12th day, followed immediately by the other long bones. Skeletal features of the skull were determined to show the latest appearance of cartilage and ossification. Hence, all elements of the hyolingual apparatus remained cartilaginous until hatching took place except for the ceratobranchial. Even though the vertebral column chondrified earlier as compared with the ribs and sternum, they ossified later. While chondrofication was present in all the regions of the vertebral column at the same time, ossification progressed from the cervical through caudal regions. The growth rate of the femur was eminently higher than that of the humerus with increase in time, particularly after the 20th day of incubation. This seems to be obviously natural because the eggs used in the study are from the broiler turkey, which gains giant muscle mass at a very short period; precocity is probably at the expense of the bones of the leg rather than those of the wing.     

Adaptation of the muscles of mastication to the flat skull feature in the polar bear (Ursus maritimus)

The muscles of mastication of the polar bear (Ursus maritimus) and those of the brown bear (U. arctos) were examined by anatomical approach. In addition, the examination of the skull was carried out in the polar bear, brown bear and giant panda (Ailuropoda melanoleuca). In the polar bear, the rostro-ventral part of the superficial layer of the M. masseter possessed the abundant fleshy portion folded in the rostral and lateral directions like an accordion. Moreover, the rostro-medial area of the superficial layer became hollow in the nuchal direction when the mouth was closed. The M. temporalis of the polar bear covered up the anterior border of the coronoid process of the mandible and occupied the almost entire area of the cranial surface. The M. pterygoideus medialis of the polar bear was inserted on the ventral border of the mandible and on the ventral part of the temporal bone more widely than that of the brown bear. As results of our measurements of the mandible, an effect of the leverage in the polar bear was the smallest in three species. In the polar bear, the skull was flat, and the space between zygomatic arch and ventral border of the mandible, occupied by the M. masseter was the narrowest. It is suggested that the muscles of mastication of the polar bear is adapted to the flat skull feature for supplementing the functions.     

Geometric morphometric study of the skull shape diversification in Sciuridae (Mammalia,Rodentia)

It is generally accepted that the high phenotypic diversity of mammals is a combined result of developmental constraint and ecological adaptation, although the influence of these endogenous and exogenous factors varies in different mammal groups. The rodent family Sciuridae represents an ideal candidate for examining phenotypic diversity in relation to phylogeny and ecological adaptations. In the present study, we investigate the effects of phylogeny and lifestyle on the skull shape in different species of Sciuridae by applying geometric morphometric methods. In addition, we investigate the importance of allometry on sciurid skull shape, because results from geometric morphometrics sometimes dispute those of traditional morphometry. Here, we identify significant associations between patristic distances obtained from molecular phylogeny and shape distances in all 3 views of the cranium and the lateral view of the mandible. Multivariate regression demonstrates that shape differences among lifestyle categories are substantial, especially in the dorsal and ventral structures after the influence of phylogeny is taken into account. Allometry plays an important role in the shape variation, although its importance on different skull structures varies. Our results indicate that complex structures of this highly diverse mammal group, which occupies different niches, are affected by ecological factors and developmental constraint.     

The head: Excluding the brain and orbit

Applications for computed tomography (CT) and magnetic resonance imaging (MRI) scans of the head (excluding the brain and orbit) include the evaluation of neoplastic, inflammatory, and traumatic disorders of the skull (including the cranium, maxilla, mandible, and temporomandibular joints); of the nasal and oral cavities; of the nasopharynx and paranasal sinuses; and of the tympanic bullae. CT and MRI provide information not obtained with routine radiography and should be considered whenever advanced surgical or radiation therapy is anticipated. In this article, the role of CT and MRI in the diagnosis of head disorders will be reviewed and illustrated with case examples.     

西藏马鹿亚种头骨的形态学观察

通过大体解剖学和动物学头骨测定的方法对马鹿头骨进行观察,并与牛、羊、马、鬣羚相比较。雄性马鹿头骨呈狭长的角锥性,额骨上有角突,角突长而分叉；鼻骨较短前窄后宽,前端呈水平状,边缘呈锯齿状,这与马、鬣羚鼻骨不相似；上颌骨接近颌前骨部位有一个犬齿齿槽,齿槽部位有6个臼齿齿槽,下颌骨有6.5个,因此上颌骨臼齿齿列比下颌骨臼齿齿列短；颧骨的前下方、鼻骨的侧面、泪骨的前上方及上颌骨的后上方,形成一个等边三角形缝隙；缝隙与鼻腔之间由一形状不规则的薄骨片隔开,这与牛、羊、马、鬣羚都不相似。     

Congenital branchial apparatus malformation in a Haflinger colt

Objective— To report the diagnosis and treatment of a branchial apparatus anomaly (BAA) associated with a mandibular malformation in a foal.
Design— Clinical report.
Animal— Haflinger foal.
Methods— A 6-day-old foal had a fluctuating cystic mass in the pharyngeal (throatlatch) region, which changed in appearance after ingestion of milk. Upper airway endoscopy and diagnostic imaging (ultrasonography, radiography, computed tomography) permitted identification of the anatomic location of a communicating tract between the lumen of the cystic mass and the pharynx. The mass was surgically removed and communication with the pharynx ligated. Histologic appearance of this mass was consistent with a branchial cyst or sinus. The mandibular malformation was managed conservatively.
Results— Surgical resection of a third branchial sinus resulted in an excellent functional and cosmetic outcome. There was no evidence of any mandibular deformity 2 years later.
Conclusion— BAA may induce secondary mandibular deformation in utero and may cause respiratory compromise postpartum. Careful surgical dissection and removal of BAA resulted in an excellent outcome.
Clinical Relevance— BAAs should be included in the differential diagnosis of a throatlatch region mass in equine neonates. Complete surgical excision is recommended and full recovery of any associated mandibular deformity may be anticipated without additional treatment in very young patients.     

Locked jaw syndrome in dogs and cats: 37 cases (1998-2005)

A consecutive series of cases of dogs and cats with locked jaw syndrome (inability to open or close the mouth) are reported in this study. Dogs were significantly overrepresented (84.0%) and adult dogs were more frequently affected (81.0%). Temporomandibular joint ankylosis due to fracture was the most common cause (54.0%) of locked jaw syndrome. Additional potential causes of locked jaw syndrome are masticatory muscle myositis, neoplasia, trigeminal nerve paralysis and central neurological lesions, temporomandibular joint luxation and dysplasia, osteoarthritis, retrobulbar abscess, tetanus, and severe ear disease. Treatment of locked jaw is directed towards the primary cause. It is important to treat the tonic spasm in order to minimize periarticular fibrosis. Surgical intervention is recommended for temporomandibular joint ankylosis. Masticatory muscle myositis treatment is initiated by gradually opening the mouth, with medical treatment based on immunosuppressive therapy. Fracture and masticatory muscle myositis are associated with a relatively good prognosis in regard to short-term outcome as compared to animals with central neurologic lesions or osteosarcoma which have a poor prognosis.     

Anatomy of the Canine Skull in Low-grade Otocephaly

An inherited low-grade otocephaly in a strain of Beagles was studied. All cases were “mild” with partial agnathia a constant feature in the adult animal. One case of high-grade otocephaly with aprosopus was recorded in an outcrossed animal. Neonatal mortalities in the low-grade type were associated with gross patency of the parietal fontanelle and hydrocephaly. Enlarged lateral ventricles were found in adult dogs, associated with incomplete union of the cranial sutures and occasional membranous-like paietal bone replacement over the patent fontanelle. Partial agnathia was not obvious in the neonate, but became apparent during postnatal skeletal development. The major anatomical differences in the skulls of these dogs were compared with normal Beagles. Malocclusion of the lower mandible and teeth against the upper jaw during development may have resulted in changes in length and width of the upper jaw and certain cranial structures. It was thought that the maloccluding lower jaw acted as a wedge against the upper jaw during mastication and these abnormal pressures, transmitted in an upward, forward, and outward direction, caused lengthening and widening of the palatine and temporal bones, and lengthening of the premaxilla and nasal bones. The nasopharyngeal meatus and palatine fissures were narrower and elongated. The pterygoid processes were pulled into a more horizontal position. It was suggested that a primary inherited abnormality may cause secondary changes in contiguous structures during development, and differentiation between primary (genetic) and secondary (acquired) anatomical abnormalities should be considered.     

Evaluation of a Collagenase Generated Osteoarthritis Biomarker in the Synovial Fluid from Elbow Joints of Dogs with Medial Coronoid Disease and Unaffected Dogs

Objective— To evaluate whether synovial fluid concentrations of an osteoarthritis biomarker in dysplastic canine elbows with medial coronoid disease (MCD) are elevated compared with unaffected elbows and to determine if these concentrations correlate to the degree of articular cartilage damage.
Study Design— Cross sectional clinical study.
Animals— Dogs (n=19; 35 elbows) with MCD and dogs (8; 16 elbows) with unaffected elbows.
Methods— Concentrations of a collagenase-generated cleavage neoepitope of type II collagen (Col2-3/4C_{long mono}, or C2C) in joint fluid from elbows were analyzed and compared between dogs with MCD and unaffected dogs. Correlation of C2C concentration with subjective grading of articular cartilage surface damage was also evaluated.
Results— Mean (±SD) C2C concentration from MCD dogs was significantly higher (112.3±24.8 ng/mL) than in unaffected dogs (76.1±16.9 ng/mL; P <.05). There was a moderate correlation between cartilage damage grade and increasing C2C concentrations ( P <.05, r=0.62)
Conclusion— C2C concentrations are elevated in the synovial fluid of dogs with MCD compared with unaffected elbows, and a moderate, significant correlation was identified between these concentrations and subjective grading of articular cartilage damage.
Clinical Relevance— This preliminary data suggest that C2C concentrations in synovial fluid may have potential as a biomarker for diagnosis of articular cartilage damage associated with MCD and as a means of objectively determining the degree of articular cartilage damage.     

Mapping of Split-Line Pattern and Cartilage Thickness of Selected Donor and Recipient Sites for Autologous Osteochondral Transplantation in the Canine Stifle Joint

Objective— To characterize donor and recipient sites for autologous osteochondral transplantation in the canine stifle joint with respect to split-line pattern and cartilage thickness.
Study Design— In vitro study.
Sample Population— Stifle joints (n=30) of dogs >20 kg.
Methods— Collagen network orientation of the hyaline cartilage coverage of the distal femur was assessed using split-line technique (n=10). Cartilage thickness was measured radiographically on osteochondral plugs harvested at the abaxial and axial surfaces of the femoropatellar joint (n=15), the most proximal abaxial aspect of the medial condyle (CO; n=5) and at both femoral condyles (n=15).
Results— Cartilage within the femoropatellar joint and both femoral condyles had mostly transversely orientated pattern of split-lines. Abaxial to the femoropatellar joint split-lines were absent. All donor sites had significantly thinner cartilage than the medial condyle (CM). Only the distal trochlea had cartilage thickness comparable to the lateral condyle (CL). The thinnest cartilage was found abaxial to the femoropatellar joint followed by CO, which was ∼2–3 times thinner than the cartilage at both condyles.
Conclusions— None of the investigated donor sites provided transplants of comparable cartilage thickness to CM. Transplants from within the femoropatellar joint should be harvested in priority as they reach cartilage morphology comparable to CL.
Clinical Relevance— Adjusting for cartilage thickness and split-line pattern may improve long-term outcome after autologous osteochondral transplantation. But surface curvature and donor-site morbidity have to be considered as well when choosing the most suitable donor site.     

Unusual case of osteopenia associated with nutritional calcium and vitamin D deficiency in an adult dog

A 6-year-old, spayed female rottweiler was presented for facial enlargement from swelling of the maxilla and mandible. The dog was fed a homemade diet deficient in calcium and vitamin D, suggesting that rubber jaw syndrome was a secondary nutritional disorder. Radiographic and tomodensitometric examinations revealed diffuse bone resorption in the skull. The plasma parathormone concentration was high, and serum 25-hydroxycholecalciferol concentration was low. Based on these findings, nutritional calcium and vitamin D deficiency associated with secondary hyperparathyroidism was diagnosed. Dietary correction resulted in clinical and biological improvement, with an increase in skull mineralization.     

MAGNETIC RESONANCE IMAGING FEATURES OF THE TEMPOROMANDIBULAR JOINT IN NORMAL DOGS

Evaluation of the canine temporomandibular joint (TMJ) is important in the clinical diagnosis of animals presenting with dysphagia, malocclusion and jaw pain. In humans, magnetic resonance imaging (MRI) is the modality of choice for evaluation of the TMJ. The objectives of this study were to establish a technical protocol for performing MRI of the canine TMJ and describe the MRI anatomy and appearance of the normal canine TMJ. Ten dogs (one fresh cadaver and nine healthy live dogs) were imaged. MRIs were compared with cadaveric tissue sections. T1‐weighted (T1‐W) transverse closed‐mouth, T1‐W sagittal closed‐mouth, T1‐W sagittal open‐mouth, and T2‐W sagittal open‐mouth sequences were obtained. The condylar process of the mandible and the mandibular fossa of the temporal bone were hyperintense to muscle and isointense to hypointense to fat on T1‐W images, mildly hyperintense to muscle on T2‐W images, and were frequently heterogeneous. The articular disc was visible in 14/20 (70%) TMJs on T1‐W images and 13/20 (65%) TMJs on T2‐W images. The articular disc was isointense to hyperintense to muscle on T1‐W images and varied from hypointense to hyperintense to muscle on T2‐W images. The lateral collateral ligament was not identified in any joint. MRI allows evaluation of the osseous and certain soft tissue structures of the TMJ in dogs.     

Temporomandibular joint dysplasia and open-mouth jaw locking in the dog

In 2 Basset Hounds, the condyloid processes of the mandible became subluxated when the mouth was opened widely, resulting in repeated episodes of locking of the coronoid process lateral to the zygomatic arch. Locking was prevented by osteotomy of a ventral portion of the zygomatic arch.     

Acute Effect of Pimobendan and Furosemide on the Circulating Renin-Angiotensin-Aldosterone System in Healthy Dogs

Background: The renin-angiotensin-aldosterone system (RAAS) is activated in states of decreased cardiac output and by certain cardiovascular therapeutic agents, such as loop diuretics and vasodilators.
Hypothesis: Short-term treatment with the inodilator, pimobendan, will not activate the circulating RAAS because its vasodilatory action will be offset by its positive inotropic property, thereby ameliorating RAAS stimulation at the juxtaglomerular apparatus. Furthermore, pimobendan will suppress RAAS activation produced by furosemide.
Animals: Nine healthy laboratory dogs were used in this study.
Methods: Experimental, cross-over study. Dogs were administered pimobendan (0.5 mg/kg q12h) for 4 days followed by furosemide (2 mg/kg q12h) and then, after a wash-out period, a combination of the drugs. Aldosterone : creatinine (A : Cr) was measured at the end of each treatment cycle.
Results: There was no significant increase in the average urinary A : Cr with the administration of pimobendan (control urinary A : Cr = 0.46, standard deviation (SD) 0.33; pimobendan A : Cr = 0.48, SD 0.28). There was a significant increase in the average urinary A : Cr after administration of furosemide (urinary A : Cr = 1.3, SD 0.70) and with the combination of furosemide and pimobendan (urinary A : Cr = 2.9, SD 1.6).
Conclusions and Clinical Relevance: Short-term administration of high-dose pimobendan, does not activate the RAAS in healthy dogs. Pimobendan did not prevent RAAS activation associated with furosemide therapy. These results in healthy dogs suggest that furosemide therapy, with or without pimobendan, should be accompanied by RAAS suppressive therapy.     

The Structure of the Masseter Muscle in the Giraffe (Giraffa camelopardalis)

In the giraffe (Giraffa camelopardalis), the masseter muscle was divided into several layers. The superficial and more medial (second) tendinous sheets of the masseter muscle fused with each other at the dorso-caudal part and a fleshy portion was located between these tendinous sheets. In the rostral part, the most superficial tendinous sheet turned around as a compact tendon and attached to the facial crest (Crista facialis). The turned tendinous sheet, however, never fused with the second tendinous sheet and this layer of the masseter muscle, that originated from the facial crest with the turned sheet, was inserted into the mandible with its fleshy portion. In the cattle, goat, sheep and Sika deer, the rostral layer of the masseter muscle arises from the facial crest with its fleshy portion and is inserted into the tubercle on the mandible through the strong tendinous sheet. In this study, the takin also showed the same structure of the masseter muscle. In the giraffe, however, the rostral layer inserted into the mandible through the strong tendinous sheet could not be distinguished, thus, there was no conspicuous tubercle on the mandible. Moreover in the masseteric region of the skull.,the giraffe was similar to the Sika deer in several ways. However, it is suggested that the giraffe exerts smaller forces on the cheek teeth than does the Sika deer because of its longer Margo interalveolaris.