In order to evaluate two therapeutic ultrasound protocols for treatment of injuries of the superficial digital flexor tendon (SDFT) a study was performed in 18 horses. In each horse, a 0.25% solution of collagenase was injected in the middle of the left SDFT. The horses were randomly and equally divided into three groups. Horses from Group A were treated with therapeutic ultrasound of 3 MHz frequency and 1 W/cm² intensity on continuous mode for six minutes; horses from Group B were treated with the same frequency, intensity, and time, but on pulsed mode; Group C was kept as controls. The treatment began 48 hours after the collagenase injection, totaling eight sessions. The horses were clinically evaluated for 40 days. Ultrasonographic images were evaluated weekly to score the severity rate (SR), which was based on echogenicity and cross sectional area of the lesion in the tendon. The induced lesion resulted on an average increase of 1.5cm in the shin circumference, pain response to digital pressure ranging from low to high and lameness ranging from grade 1 to 3. Regression of clinical signs were detected on average in nine days in Group A, 12 days in Group B, and 21 days in Group C. Decreases of the SR after 40 days were 42.5, 57.7 and 34.1% in groups A, B and C, respectively. Histological evaluation demonstrated intense neovascularization and fibroblastic activity on treated groups (A and B), when compared to the controls. These results suggest that UST is effective in reducing clinical signs of tendinitis.
equine; ultra-sound; tendon
