A novel approach for tendinopathy induction in donkeys using artificial heat stimulation strategy

Abstract

Animal models for tendonitis are essential for studying the disease’s mechanism and pathogenesis, and evaluating different therapeutic protocols. The temperature seems to play a significant role in tendinitis initiation. The aim of this study was the generation of a novel, safe and cheap tendinitis model, and validation of its reliability. The effect of microwave diathermy (30 watts for 30 min) on the flexor tendons of donkeys as animal models was investigated after 15, 30 and 60 days. The evaluation was based on geometric analysis, ultrasonography, histomorphometric analysis and scanning electron microscopy (SEM). Microwave diathermy was capable of successfully inducing well-defined lesions in the superficial digital flexor tendon (SDFT) as well as the deep digital flexor tendon (DDFT). The results showed that all the animals exhibited signs of lameness, starting on day 15 and reaching on maximum on day 30. A significant increase in limb circumference was also detected on day 30 (P<0.05). Furthermore, the geometrical analysis of the proportion of induced lesion (PIL) in correlation with the tendon diameter, revealed that PIL was at the maximum width on day 30 (20.6 ± 1.2% for SDFT and 15.7 ± 0.7% for DDFT), as detected by ultrasound. Moreover, a high number of rounded tenocytes, bleeding, severe matrix disruption, and an increase in fiber thickness were detected by histomorphometric analysis. Also, the matrix alignment was severely disrupted in both SDFT and DDFT by day 30, as confirmed by SEM. In conclusion, using microwave diathermy for induction of tendonitis in donkey is a reliable, minimally invasive, and cost-effective tendonitis model.