Tendinopathy of the superficial flexor of the finger in horses: morphological changes in the middle third of the pastern

Abstract

A feature of the training process in riding sports horses is the repeated uneven maximum weight loads on the limbs and, in particular, on their tendon-ligamentous apparatus. The study used the tendons of the superficial flexor of the pectoral and pelvic extremities of sports horses that died from causes unrelated to tendon injuries. Tendinopathy was diagnosed in all animals during their lifetime. Isolated hands of the thoracic limb and feet of the pelvic limb were selected, as well as samples of the tendon of the superficial flexor of the finger of 15 sports horses aged 6 to 15 years. Histological studies were carried out according to a generally accepted technique: the material was fixed in a 10% formalin solution, poured into paraffin, sections were prepared, which were stained with hematoxylin and eosin to identify the general morphological picture, according to Van Gieson to assess the condition of bundles of collagen fibers and alcyan blue to identify glycosaminoglycans. The micropreparations were studied using Jenamed-2 and MicroScreen microscopes. As a result of the conducted research, original data were obtained. Signs of chronic inflammation, numerous foci of tissue destruction in combination with moderate reactive changes in the tissue indicate a long, long-term course of the pathological process. Since the tendon is a moderately vascularized tissue, insufficient perfusion does not allow maintaining redox processes at the required level. Therefore, in conditions where metabolism is restored in well-vascularized skeletal muscles, this process has not yet been completed in tendons. The conditions of hypoxia themselves create a background for the development of connective tissue and sclerosis. It is possible that this is how the signs of sclerosis gradually increase in the epithenonia and perithenonia, as well as in the walls of blood vessels, which were identified in our studies.