DXA reference values of the humanoid sheep model in preclinical studies

Area of Science:

• Veterinary medicine
• Orthopedics
• Pre-clinical research

Background:

• Merino land sheep are a valuable pre-clinical model for skeletal diseases like osteoporosis.
• Lack of established reference parameters hinders interpretation of research data.
• This study aims to define skeletal reference parameters (peak bone mass, T-Score) for Merino sheep.

Purpose of the Study:

• To determine peak bone mass (PBM) and T-score reference parameters in Merino land sheep.
• To establish a standard for comparing animal model data with human studies.
• To improve the reliability and comparability of osteoporosis research using this animal model.

Main Methods:

• 116 Dual Energy X-ray Absorptiometry (DXA) measurements were conducted on 74 untreated Merino sheep (average age 57 months).
• Bone mineral density (BMD), bone mineral content (BMC), and fat content were analyzed using human regions of interest (ROI).
• Peak bone mass (PBM) and T-scores were calculated for each animal.

Main Results:

• BMD and BMC showed significant correlations with animal age (p=0.043 and p≤0.001, respectively).
• Age-dependent analysis revealed a wide scatter of BMD and BMC values between 50-90 months, with values falling below the regression line after 90 months.
• Significant differences in BMD were observed across different ROIs, indicating the need for standardized reference groups.

Conclusions:

• Peak bone mass (PBM) and T-scores were successfully determined for Merino land sheep.
• An independent reference group, established from 4-6-year-old sheep, is recommended for PBM and T-score.
• Animals aged seven years and older are recommended for osteoporosis modeling to ensure a plateau phase in bone density is reached.