The effects of bovine recombinant growth hormone administration on insulin-like growth factor-I and the haemopoietic system in thoroughbred geldings.
Authors: Champion Z J, James E A, Vickers M H, Breier B H, Casey P J
Journal: Veterinary journal (London, England : 1997)
Summary
# Editorial Summary Recombinant bovine growth hormone (rbGH) administration triggers dose-dependent increases in equine insulin-like growth factor-I (IGF-I) and affects circulating immune cells, raising questions about its potential therapeutic application in horses. Champion and colleagues administered single intramuscular injections of rbGH at three dose levels (5, 10, or 50 µg/kg) to Thoroughbred geldings and tracked IGF-I concentrations and haematological parameters, using a validated radioimmunoassay to measure circulating IGF-I reliably in equine plasma. The highest dose produced a 90% elevation in IGF-I by 24 hours, with white blood cell counts peaking at 12 hours post-injection across all treatment groups; haemoglobin concentrations increased significantly at the two higher doses, whilst red blood cell counts remained unchanged. These findings confirm that exogenous growth hormone elicits measurable biological responses in horses, suggesting that doses of 10 µg/kg or above warrant further investigation for conditions where enhanced growth factor activity and haematological support might prove beneficial—though the clinical applications and long-term safety profile remain to be established through additional research.
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Practical Takeaways
- •Recombinant bovine growth hormone is biologically active in horses and produces measurable systemic effects on growth factor and haematological parameters
- •Doses of 10 microg/kg or higher appear necessary for therapeutic effect based on IGF-I and haemoglobin response patterns
- •Practitioners should be aware of potential haemopoietic effects if rbGH is considered for equine therapeutic use
Key Findings
- •IGF-I levels increased in dose-dependent manner with highest values between 12-24 hours post-administration
- •50 microg/kg rbGH dose produced 90.2±10.8% increase in IGF-I at 24 hours
- •White blood cell count increased following rbGH administration with peak at 12 hours after 50 microg/kg dose
- •Haemoglobin significantly increased at 24 hours (P<0.05) at doses of 10 and 50 microg/kg compared to vehicle control