In this study we have investigated the potential of optical techniques to monitor changes in bone mineral density (BMD) via changes in scattering coefficient. For each of five bone samples, diffuse reflection and transmission coefficients were measured over the wavelength range 520-960 nm using an integrating sphere and CCD spectrometer. These were converted into optical absorption and scattering coefficients using a Monte Carlo inversion procedure. Measurements were made on samples immersed in formic acid solution for different lengths of time in order to investigate the effect of reduction in BMD on the optical properties. After full demineralization, the optical scattering coefficient fell by a factor 4. From the observed degree of fluctuation of the measurements, we estimate that BMD could be measured with an accuracy of 7% if optical scattering can be measured with an accuracy of 10%. We also report preliminary measurements of bone scattering using optical coherence tomography (OCT). An inter-side variability of 3% is obtained on dry samples with and without overlying periosteum. These results suggest that minimally invasive techniques for measuring optical scattering, such as OCT, may have a role in monitoring regional changes in BMD. This could be an important advance in our understanding of bone remodelling and its relationship to osteoarthritis. Both the integrating sphere and OCT measurements also suggest that light transport in bone is spatially anisotropic. OCT was used to assess probability of obtaining results in vivo.

A combination of two-photon fluorescence (TPF), second harmonic generation (SHG) and coherent anti-Stokes Raman scattering (CARS) imaging has been used to investigate the elastin fibre network in healthy equine articular cartilage from the metacarpophalangeal joint. The elastin fibres were identified using their intrinsic twophoton fluorescence and immuno-staining was used to confirm the identity of these fibres. SHG was used to reveal the collagen matrix and the collagen fibre orientations were determined from their SHG polarization sensitivity, while CARS was used to clearly delineate the cell boundaries. Extensive elastin fibre networks were found in all the joint regions investigated. The elastin was found predominantly in the superficial zone (upper 50 lm) and was aligned parallel to the articular surface. Elastin was also detected in the pericellular matrix surrounding the superficial chondrocytes; however, individual fibres could not be resolved in this region. Variations in the density and organization of the fibres were observed in different regions on the joint surface.

Optical coherence tomography and polarization-sensitive optical coherence tomography images of equine articular cartilage are presented. Measurements were made on intact joint surfaces. Significant (e.g. × 2) variations in the intrinsic birefringence were found over spatial scales of a few millimetres, even on samples taken from young (18 month) animals that appeared visually homogeneous. A comparison of data obtained on a control tissue (equine flexor tendon) further suggests that significant variations in the orientation of the collagen fibres relative to the plane of the joint surface exist. Images of visually damaged cartilage tissue show characteristic features both in terms of the distribution of optical scatterers and of the birefringent components.

Summary Techniques developed for the detection and simultaneous recording of certain events in the respiratory and limb cycles are presented. The respiratory cycle and limb cycle were found to be in‐phase only at the canter and gallop. The significance of any time relationship between events in respiration and in locomotion is discussed. Résumé On indique ici des techniques concues pour la recherche et l'enregistrement simultané de certains phénomènes de la locomotion et de la respiration. Les cycles respiratoire et du mouvement des membres paraissent n‘être “en phase” qu'au “canter” et au galop. On discute la signification des relations existant ainsi entre la respiration et la locomotion. Zusammenfassung Es werden Methoden beschrieben, die gewisse Ereignisse im Atemzyklus und Bewegungsablauf messen und simultan aufnehmen können. Atemzyklus und Bewegungsablauf sind nur im langsamen (Canter) und schnellen Gallop aufeinander abgestimmt. Die Signifikanz einer zeitlichen Beziehung zwischen Atmung und Fortbewegung wird diskutiert.

Summary A fibrous lesion in the first phalanx of the foreleg of an 8‐month‐old castrated male Thoroughbred is identified as similar in every way to the condition recognised in humans and described as non‐ossifying fibroma. Surgical correction of this condition is outlined, the recovery indicated and histopathology discussed. Resúmé Une lésion fibreuse de la première phalange d'un antérieur chez un poulain hongre âgé de 8 mois a été identifiée dans tous ses aspects à une affection reconnue chez l'Homme et décrite comme étant un fibrome non ossifiant. On esquisse la correction chirurgicale de cette affection. Le processus de guérison est décrit et l'histopathologie est commentée. Zusammenfassung Eine fibröse Veränderung an einem vorderen Fesselbein eines 8 Monate alten Vollblutwallachs ist als identisch mit dem menschlichen nicht verknöchernden Fibrom erkannt worden. Die chirurgische Behandlung, die Heilung und die histopathologischen Befunde der Krankheit werden beschrieben.

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SUMMARY A graphic representation is presented of respiratory sounds recorded by a radio‐stethoscope from normal horses exercised at the walk, trot, canter and gallop. Methods whereby inspiratory and expiratory sounds were distinguished are discussed. The form of amplitude envelopes of the sounds recorded at different gaits are compared. Certain measurements of relative amplitudes and the form of amplitude envelopes of the recorded respiratory sounds can be recognised as typical of normal horses when exercised at the canter and gallop. The influence of some physiological events (e.g. deglutition on the rhythm of normal respiration at the canter and gallop) is indicated. RÉSUMÉ On donne une représentation graphique des sons respiratoires recueillis sur le cheval normal à l'aide d'un radio stéthoscope au pas, au trot, au canter, au galop. Les méthodes permettant de différencier les sons inspiratoires et des sons expiratoires, sont discutées. On compare les résultats obtenus aux différentes allures. Certaines mesures des amplitudes relatives et la forme des amplitudes globales peuvent être considérées comme caractéristiques pour un cheval exercé au canter ou au galop. L'influence de facteurs physiologiques tels que la déglutition sur le rythme de la respiration normale, est envisagée. ZUSAMMENFASSUNG Die radio‐stethoskopisch aufgenommenen Atemgeräusche normaler Pferde im Schritt, Trab, langsamen und schnellen Galopp werden graphisch wiedergegeben. Die Methoden zur Unterscheidung exspiratorischer und inspiratorischer Geräusche werden besprochen. Die Amplitudenumrisse der Geräusche werden in verschiedenen Gangarten verglichen. Gewisse Messungen relativer Amplituden und die Form der Amplitudenumrisse der Atem geräusche können als typisch für das im Kanter oder schnellen Galopp arbeitende Pferd gelten. Physiologische Einflüsse, z.B. Abschlucken im Rhythmus der normalen Atmung im Kanter oder Galopp, werden diskutiert.

The detection of radionuclide activity in the living equine skeleton, using bone seeking radiopharmaceuticals and a hand-held radiation detector, is reported. Pathological changes in bone can be detected and subsequent development monitored. The availability and use of this diagnostic technique in equine practice is discussed.