A retrospective case-control study was conducted to identify and quantify risk factors for serious musculoskeletal injury sustained at 4 Australian metropolitan racetracks. During the period of study (August 1988-July 1995) there were 196 cases from flat racing, 52 cases from hurdle racing and 53 cases from steeplechases. The incidences of fatal musculoskeletal injuries per start for flat, hurdle and steeple races were 0.06, 0.63 and 1.43% respectively. Logistic regression identified harder track surfaces, horses being older than age 3 years, one racecourse (Flemington) and jumping races as significant risk factors which increased the risk of musculoskeletal breakdown. The incidence of fatal musculoskeletal injuries for flat races at the 4 study tracks was similar to that reported in the UK but less than the USA.Death rates for hurdle and steeple races in the study population were higher than in the UK. Strategies to reduce the incidence of serious musculoskeletal injuries may include avoidance of excessively hard track surfaces through closer regulation of track moisture content; implementation of more rigorous prerace lameness examinations of horses, particularly older horses; and altering the design and number of jumps in hurdle and steeple races. The quantification of risk, as we have reported here, is the first step towards addressing the causes of musculoskeletal breakdown and should help in applying a reasoned approach to intervention measures that may be effective in reducing racing injuries.

The nasal region plays a key role in sensory, thermal, and respiratory physiology, but exploring its evolution is hampered by a lack of preservation of soft-tissue structures in extinct vertebrates. As a test case, we investigated members of the "bony-headed" ornithischian dinosaur clade Pachycephalosauridae (particularly Stegoceras validum) because of their small body size (which mitigated allometric concerns) and their tendency to preserve nasal soft tissues within their hypermineralized skulls. Hypermineralization directly preserved portions of the olfactory turbinates along with an internal nasal ridge that we regard as potentially an osteological correlate for respiratory conchae. Fossil specimens were CT-scanned, and nasal cavities were segmented and restored. Soft-tissue reconstruction of the nasal capsule was functionally tested in a virtual environment using computational fluid dynamics by running air through multiple models differing in nasal softtissue conformation: a bony-bounded model (i.e., skull without soft tissue) Abbreviations used: acPM 5 anastomotic canal in premaxilla; aEth 5 ethmoid artery; air 5 airway; anas 5 anastomosis between palatine, lateral nasal, and dorsal alveolar vessels; aSO 1 LN 5 anastomosis between supraorbital and lateral nasal vessels; aSph 5 sphenopalatine artery; at 5 potential accessory turbinate; bch 5 bony choana (fenestra exochoanalis); bLN 5 branches of lateral nasal vessels; bMN 5 branches of medial nasal vessels; cap 5 cartilaginous nasal capsule; caud co 5 caudal concha; cDA 5 dorsal alveolar canal; ch 5 choana (fenestra endochoanalis); cLN 5 canal for lateral nasal vessels; cMN 5 canal for medial nasal vessels; co 5 concha; cPM 5 canal in premaxilla; cSO 1 LN 5 canal for anastomosis between supraorbital and lateral nasal vessels; cSO 5 canal for supraorbital vessels; DA 5 dorsal alveolar vessels; f 5 frontal; fSO 5 suborbital fenestra; gLN 5 groove for lateral nasal vessels; j 5 jugal; lac 5 lacrimal; Lc 5 lacrimal canal; LN 5 lateral nasal vessels; max 5 maxilla; mid co 5 middle concha; MN 5 medial nasal vessels; mu 5 mucosa; nar 5 naris; nas 5 nasal; nc 5 nasal capsule; ng 5 nasal gland; npd 5 ductus nasopharyngeus; ns 5 nasal septum; ob 5 olfactory bulb; OfC 5 olfactory conchal vessels; olf e 5 olfactory epithelium; om 5 olfactory meatus; ot 5 olfactory turbinate; p 5 parietal; PA 5 palatine vessels; pl 5 palatine; pm 5 premaxilla; po 5 postorbital; post 5 postvestibular ridge; preco 5 preconcha; preco rec 5 preconchal recess; prf 5 prefrontal; ps 5 parasphenoid rostrum; pt 5 pterygoid; q 5 quadrate; qj 5 quadratojugal; RC 5 respiratory conchal vessels; res e 5 respiratory epithelium; sDS 5 dorsal sagittal sinus; so1 5 supraorbital 1; so2 5 supraorbital 2; som 5 supraorbital bone (mineralized supraorbital membrane); sOf 5 olfactory sinus; SO 5 supraorbital vessels; sq 5 squamosal; t 5 tongue; turb 5 turbinate; v 5 vomer; vest 5 vestibulum nasi; vp 5 ventromedian process.

Models of the mammalian jaw have predicted that bite force is intimately linked to jaw gape and to tooth position. Despite widespread use, few empirical studies have provided evidence to validate these models in non-human mammals and none have considered the influence of gape angle on the distribution of stress. Here using a multi-property finite element (FE) model of Canis lupus dingo, we examined the influence of gape angle and bite point on both bite force and cranial stress. Bite force data in relation to jaw gape and along the tooth row, are in broad agreement with previously reported results. However stress data showed that the skull of C. l. dingo is mechanically suited to withstand stresses at wide gapes; a result that agreed well with previously held views regarding carnivoran evolution. Stress data, combined with bite force information, suggested that there is an optimal bite angle of between 25° and 35° in C. l. dingo. The function of these rather small bite angles remains unclear.

Three adaptive hypotheses have been forwarded to explain the distinctive Neanderthal face: (i) an improved ability to accommodate high anterior bite forces, (ii) more effective conditioning of cold and/or dry air and, (iii) adaptation to facilitate greater ventilatory demands. We test these hypotheses using three-dimensional models of Neanderthals, modern humans, and a close outgroup (), applying finite-element analysis (FEA) and computational fluid dynamics (CFD). This is the most comprehensive application of either approach applied to date and the first to include both. FEA reveals few differences between , modern humans, and Neanderthals in their capacities to sustain high anterior tooth loadings. CFD shows that the nasal cavities of Neanderthals and especially modern humans condition air more efficiently than does that of , suggesting that both evolved to better withstand cold and/or dry climates than less derived We further find that Neanderthals could move considerably more air through the nasal pathway than could or modern humans, consistent with the propositions that, relative to our outgroup, Neanderthal facial morphology evolved to reflect improved capacities to better condition cold, dry air, and, to move greater air volumes in response to higher energetic requirements.

Four variations of abductor muscle prosthesis for treating laryngeal hemiplegia were evaluated in 153 horses by questionnaire, and in the 100 Thoroughbred racehorses in this group survival analysis was used to compare their racing performances and earnings with those of 400 control horses. The questionnaire indicated that the technique which included a ventriculectomy and 2 prostheses was regarded as being the most successful (P less than 0.01) and resulted in the least residual stertor (P less than 0.001). Survival analysis showed that there was no significant difference between the treated group of horses and the control horses (P greater than 0.05).

Convoluted nasal passages are an enigmatic hallmark of Ankylosauria. Previous research suggested that these convoluted nasal passages functioned as heat exchangers analogous to the respiratory turbinates of mammals and birds. We tested this hypothesis by performing a computational fluid dynamic analysis on the nasal passages of two ankylosaurs: Panoplosaurus mirus and Euoplocephalus tutus. Our models predicted that Panoplosaurus and Euoplocephalus would have required 833 and 1568 thermal calories, respectively, to warm a single breath of air by 20°C. Heat recovery during exhalation resulted in energy savings of 65% for Panoplosaurus and 84% for Euoplocephalus. Our results fell well within the range of values for heat and water savings observed in extant terrestrial amniotes. We further tested alternate airway reconstructions that removed nasal passage convolutions or reduced nasal vestibule length. Our results revealed that the extensive elaboration observed in the nasal vestibules of ankylosaurs was a viable alternative to respiratory turbinates with regards to air conditioning. Of the two dinosaurs tested, Euoplocephalus repeatedly exhibited a more efficient nasal passage than Panoplosaurus. We suggest that the higher heat loads associated with the larger body mass of Euoplocephalus necessitated these more efficient nasal passages. Our findings further indicate that the evolution of complicated airways in dinosaurs may have been driven by the thermal requirements of maintaining cerebral thermal homeostasis.

No abstract

No abstract