Intralesional polysulphated glycosaminoglycan as treatment of equine collagenase induced tendinitis: clinical, ultrasonographic and histopathologic evaluation

Abstract

The effect of intratendineous injections of polysulphated glycosaminoglycan (PSGAG) as treatment of collagenase-induced tendonitis was studied. Two groups (GI and GII) of five Arabian horses each, males and females, two to six year-old, were submitted to experimental tendinitis of the superficial digital flexor tendon of the left thoracic limb by intratendineous injection of 1.0ml of collagenase (2.5mg/ml). Seven days after the induced-lesions were created, the horses of GI received five intralesional injections of 1.0ml (125mg) of PSGAG, every four days. Horses of GII received injections of saline in the same dose and rate. Clinical and ultrasonographic evaluations were performed periodically, during 150 days. All animals showed lameness, increased local pain, heat and swelling 24 hours after the injury was created. All signs, except to swelling, which remained visible by the end of the study, showed regression in all animals. Lesions of variable size, shape and position were evidenced by the ultrasonographic evaluation, reaching maximum severity between the seventh and the 23rd days. By the end of the study, the echogenicity grade ranged from 1 to 2, and the grade of fiber alignment from 0 to 2. The histopathologic analysis demonstrated repair areas with intense fibroplasia and neovascularization, collagen fibers poorly organized, and thickened hypercellular endotenon. The data of this study did not show significant differences between the treated and control groups, therefore leading to the conclusion that the intralesional injection of PSGAG did not have beneficial effects in the treatment of collagenase-induced tendinitis.