Morphologic, Thermographic and ¹³³Xe Clearance Studies on Normal and Diseased Superficial Digital Flexor Tendons in Race Horses

Abstract

SUMMARY Normal and diseased superficial digital flexor tendons of 104 Thoroughbred race horses have been studied by gross and microscopic examination. The vascularization was studied by means of microangiography. Infra‐red thermography was attempted as a method for early detection of acute tendon lesions. The functional blood flow of normal and diseased tendons was studied by means of the elimination curve of 133Xe after intra‐tendinous injection of the isotope. Finally, a correlation was made in nine horses with tendon lesions examined by infra‐red thermography, 133Xe‐elimination, micro‐angiography, and histology. It was concluded that degenerative intratendinous changes preceded clinical signs of tendon lesions. Multiple minute fibrillary ruptures initiate a reparatory inflammatory process in the tendon. Slight tendon lesions may heal with rest and adjusted training. The prognosis of complete restitution after severe lesions is poor. RÉSUMÉ Les tendons flechisseurs superficiels normaux ou malades de 104 chevaux der Pur Sang ont étéétudiés cliniquement et histologiquement. La Vascularisation fut étudiée par microangiographie. La thermographie infra rouge fut utilisée pour essayer de détecter précicement les lésions tendineuses aigues. L'irrigation des tendons normaux et malades fut étudiée en tracant la courbe d'élimination du 133Xe après injection intra tendineuse de cet isotope. Une correlation fut établie pour neuf chevaux porteurs de lésions entre la vitesse d'élimination du 133Xe, la microangiographie, et l'histologie. On peut en conclure que des changements dégénératifs au sein des tendons précèdérent les signes cliniques de tendinite. De légères lésions tendineuses peuvent cicratiser grace au repos et à un traitement adapté. Par contre le pronostic d'une restauration complète faisant suite à des lésions graves reste sombre. ZUSAMMENFASSUNG Von 104 Vollblutpferden wurden normale und erkrankte oberflächliche Beugesehnen makroskopisch und mikroskopisch untersucht. Die Vaskularisation wurde mittels der Mikroangiographie studiert. Es wurde versucht durch Infrarot‐Thermographie akute Sehnenschäden möglichst frühzeitig nachzuweisen. Das Funktionieren der Blutversorgung in gesunden und erkrankten Sehnen wurde mittels der Eliminationskurve von 133Xe untersucht, nachdem das Isotop intratendinös injiziert worden war. Zu guter Letzt wurde versucht die Resultate der Infrarot‐Thermographie, der 133Xe‐Elimination, Mikroangiographie und Histologie bei neun Pferden zu korrelieren. Die Befunde führten zum Schluss, dass degenerative, intratendinöse Veränderungen den klinischen Manifestationen von Sehnenschäden vorangehen. Multiple, feine Faserrisse führen zu einer reparatorischen Entzündung in der Sehne. Leichte Sehnenschäden können ausheilen unter Ruhestellung und angepasstem Training. Die Prognose für eine vollständige Restitution nach schweren Schäden ist ungünstig.

Inflamm-Aging and Arachadonic Acid Metabolite Differences with Stage of Tendon Disease

“…This suggests a secondary (cellular) clearance mechanism for PGE 2 degradation whereby local PGE 2 levels can be regulated [46]. The increased vascularity of tendon that occurs after recent injury may also be a contributing factor to the paradoxical lower levels of PGE 2 after injury [48], as the increased vascular perfusion is likely to facilitate efficient systemic prostaglandin clearance. In addition to vascular clearance, the lower levels of PGE 2 in sub-acute tendon injury could also be attributable to lipid substrate re-routing towards the resolving pathways that are activated during inflammation.…”

Infrared Thermography in Zoo and Wild Animals

“…Experienced trainers and veterinarians are able to identify potentially lame animals up to 2 weeks before the animal actually shows clinical signs. 13,22,27 General indicators of altered thermoregulation can be physiologic or pathologic, as follows:…”

Reliability and repeatability of thermographic examination and the normal thermographic image of the thoracolumbar region in the horse

“…Isolated areas of thermal changes due to pathology can cause both thermal hotspots and cold spots, the actual temperature of which is independent of normal thermoregulation (Love 1980;Ring 1990;Turner 1991;Waldsmith and Oltmann 1994). Given that visual pattern recognition depends on contrast between areas within an image, a pathological area causing a thermal hotspot (Delahanty and Georgi 1965;Stromberg 1973;Palmer 1980;Eddy et al 2001) may therefore be more evident at the lower, pre-equilibration temperatures, as the temperature difference between normal and abnormal areas would be greater and the converse would be true for thermal cold spots. This is only true, however, when the horse is brought from the outside, ambient temperature into a warmer inside environment for imaging, as occurred in this study.…”