Foals Developmental Orthopedic Disease Associated with Metabolic and Biometric Characterization of Pregnant Overweight Crioulo Mares

Background : Musculoskeletal changes in growing foals can be linked to metabolic disorders which affect the cartilage metabolism associated of obesity during the late gestation of the mares, negatively affecting the athletic performance of the otherwise prospective foals. High basal insulin levels can be associated with increased weight and obesity of the mares, altering the supply of the glucose to the fetus and the production of IGF-1, which plays an important role in the endochondral cartilage metabolism. The present study aims to describe the association of the articular and the physeal possible lesions and the IGF-1 levels of the foals to metabolic and biometric measurements alterations of the overweight Crioulo mares in the late gestation. Materials, Methods & Results : A prospective and observational cohort study was conducted using the foals and the overweight mares at field conditions. Twenty-eight foals and their overweight mothers were utilized. The foals’ biometric and metabolic features as weight and height; glucose, total cholesterol, cholesterol HDL, triglycerides, basal insulin, leptin, glucose, total T4 and IGF-1 were analyzed, from the birth until the weaning period around sixth month of life of it. All the foals, at the weaning period, were submitted to the radiograph examination of the tarsal joints and the metacarpal-phalangeal joints to evaluate signs of lesions and the possible distal metacarpal physeal changes, respectively. The mares’ biometric and metabolic features as weight, height and fat tail-head deposition; basal insulin, leptin, glucose, total cholesterol, cholesterol HDL and triglycerides were analyzed at the final period of gestation. The basal insulin levels of the foals at the second, fourth and sixth month of life were 9.87 + 1.82 µUI/mL, 9.13 + 1.94 µUI/mL, 9.39 + 2.54 µUI/mL. The IGF-1 levels of the foals at the second, third, fourth, fifth and sixth month of life were 290.27 + 79.72 ng/mL; 180.77 + 66.22 ng/mL; 151.79 + 46.64 ng/mL; 110.81 + 33.13 ng/mL and 89.59 + 14.00 ng/mL. Foals presented osteoarthritis (92.85%) of the distal tarsal joints and 50% of it presented physitis of the distal metacarpal epiphyseal plate. The weight and the basal insulin levels of the mares at the last three months of gestation were 501.80 + 6.4 kg, 511.76 + 8.0 kg, 533.23 + 8.2 kg and 11.7 + 2.1 µUI/mL, 9.8 + 1.1 µUI/mL, 13.7 + 1.6 µUI/mL, respectively. Discussion : In the present study, from the second to the sixth month of the period life, the foals showed IGF-1 levels of 290 to 89 ng/mL, and demonstrated, at 6-month-old, a prevalence of 92.85% of distal tarsus lesions and 50% of physitis of the distal metacarpal epiphyseal plate. In association, the overweight mares showed an increase of the insulin basal levels when nearing parturition. The occurrence of physitis in 50% of the 6-month-old foals in the present study demonstrate that the metabolic changes are involved in this process and the IGF-1 levels were observed to be lower than in healthy foals of other breeds. The lower IGF-1 levels during the developmental period of the foals are associated with a decrease of bone density and mass, musculoskeletal atrophy and osteoarthritis. In the present study, the decreasing curve of IGF-1 levels ( P < 0.05) of the foals, from the second to sixth month of life, is similar to others researches with foals from other breeds from 0 to 7 months of life. In previous researches with Crioulo horses, it was observed that foals aged less than 18 months had up to 100% of prevalence of articular tarsus lesions. This suggest that the tarsus lesions observed in 92.85% of the 6-month-old foals in the present study, could not heal and that lesions should remain in the foals to adulthood.