The study was carried out in the superficial digital flexor tendon (SDFT) of the right forelimb of nine clinically apparently donkeys for evaluation the efficacy of Polysulfated Glycosaminoglycan (PSGAG) and Dexaphenylarthrite in treatment of artificial induced tendonitis. To achieve this goal, clinical, ultrasonography, biochemical and histopathological examinations were concluded. Tendonitis of the SDFT was induced by using bacterial collagenase enzyme from Clostridium histolyticum. Donkeys were classified into three groups. Group Ι (after induction of tendonitis they left as control group= 3 donkeys). Group ΙΙ, 3 days after induction of tendonitis, they received five IM injections of 5ml PSGAG (100 mg/ml) every four days. Group ΙΙΙ, 3 days after induction of tendonitis, they received Dexaphenylarthrite in a dose of 20 ml/day for the first two days followed by 10 ml/day for the other three days. From this study, it can be concluded that PSGAG had beneficial effects in treatment of artificial induced tendonitis in donkeys rather than Dexaphenylartrite based on clinical, ultrasonography, biochemical and histopathological findings.