Does osteochondrosis affect the toe-heel and medio-lateral hoof balance in growing Warmblood foals?

Abstract

Introduction: Osteochondrosis (OC) is a frequently observed developmental disease in young horses. It has been diagnosed in foals as young as several days of age and can result in (subclinical) lameness. Aim of the study: To investigate whether the presence of osteochondrosis at a young age affects the toe-heel and medio-lateral hoof balance, measured with the asymmetry index of the peak vertical forces and coefficient of variation. Materials and methods: Pressure plate measurements at walk and trot of eleven Dutch Warmblood foals during their first 24 weeks of life were used to determine toe-heel and medio-lateral hoof balance of the peak vertical force as described by Oosterlinck et al. (2013). Radiographic evaluation for the presence of osteochondrosis of tarsocrural and femoropatellar joints was performed at 4–6 weeks and after 6 months. Results: Foals with osteochondrosis showed several small differences in hoof balance curve patterns, mainly at 4-6 and 12-16 weeks of age. The coefficients of variation of medio-lateral balance of the positive group were different in week 6, while the ASI of toe-heel balance was affected mostly during week 12 and 16, both in the hind limbs at trot. Foals with osteochondrosis presented with a different variation pattern medio-laterally and a quicker shift towards loading of the toe during the stance phase. Conclusion: Gorissen et al. (2016) found that foals with osteochondrosis show a lower peak vertical force in the OC-affected hind limbs during week 4 and 6. This study demonstrates these foals also present with a different distribution of pressures in toe-heel and medio-lateral hoof balance compared to unaffected foals. It should be noted that this is not limited to the 4-6 week time period. Foals with persistent lesions show multiple significant differences at later ages than 4-6 weeks as well, compared to foals with no or regressed lesions. This possibly indicates that regressing lesions have little effect besides a slight subclinical lameness, but that foals with persistent lesions - even if not clinically lame - will load their feet differently during this important growth period. This may affect their development and performance later in life.