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Alternatives to castration in horses

Alternatives to castration in horses. Why castrate? . Aggressive behavior Sex-related aggression Dominance Related aggression No distractions at shows Will perform, with mares, in classes Easier to manage 5 ft vs. 7 ft fencing Limited areas; can pasture with mares.

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Alternatives to castration in horses

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  1. Alternatives to castration in horses

  2. Why castrate? • Aggressive behavior • Sex-related aggression • Dominance Related aggression • No distractions at shows • Will perform, with mares, in classes • Easier to manage • 5 ft vs. 7 ft fencing • Limited areas; can pasture with mares

  3. What are some alternatives? Progestin therapy GnRH vaccination

  4. Progestins • Progestins inhibit Leutenizing Hormone production • Results • Reduced Leydig cell activity • Reduced testosterone levels in blood plasma • Reduced ejaculate volume • Reduced libido • Reduced sperm production *Stephen J. Roberts (VT) & Bonnie V. Beaver (TX)

  5. Gonadotropin releasing hormone Objective: To investigate the effect of GnRH on testicular function

  6. The studies: The First Study • Six yearling colts were divided into three groups 1) control 2) subcutaneous & 3) intramuscular vaccination • They were fed to ensure adequate growth throughout study • Vaccinated against tetanus

  7. The first study • Injections • 2 cc of mineral oil based GnRH vaccine • The control group: never injected • The Subcutaneous group: emulsion on the side of neck • Intramuscular group: injection in the neck

  8. The first study • Measurements and Tests • *Jugular vein blood assayed before study for testosterone level and GnRH antibodies • *Scrotal diameters and body weights were measured prior to study • Body weights and Blood assays • Scrotal diameters and testicular lengths • Blood samples • Antibody Assays • Semen Collection and Examination • Daily sperm production • Testis Histology • Morphometric Analysis

  9. The Results • No weight differences • Testosterone levels • The treated colt’s • Testes failed to grow during first 32 weeks • Irregular groups of Leydig cells • Reduced volume of semineferous tubules • Reducd Leydig cell volume *No “P” values given

  10. The Second Study • Twelve 2-year-old colts divided into two groups: 1) 200 mg dose 2) 400 mg dose of water based GnRH vaccine • They were run in paddocks and fed to maintain condition • Vaccinated against strangles and tetanus

  11. The Second Study • Injections: given Intramuscularly • *Water based vaccine vs • *Mineral Oil based vaccine • Lesions • Soreness • Scarring

  12. The Second Study • Measurements and Tests • Testosterone concentrations and semen quality assessed before trial • Body Weights • Testicular widths and lengths • Blood samples • Testosterone concentrations • Antibody assays • Semen examination • Libido

  13. Results • Vaccination Dose on body weight and testicular dimensions • Not significantly different (P>0.05) • Only slight swelling at site • Vaccination dose on semen characteristics • Significantly different in percentage of live, normal sperm (P<0.05) • No significant effects on antibody titres or testosterone levels • (P>0.05) • Displayed gelding-like behavior

  14. The Third Study • Four standardbred stallions: 3 treated and 1 control • Vaccinated with water soluble GnRH vaccine • Kept in paddocks during day & stalls at night *September to January

  15. The Third Study • Measurements and Tests • Hormone assays • Semen collection & behavior • Semen evaluation • Testes examination • Testicular histology • Site examination

  16. Results • Testosterone levels decreased, but varied by individual • Libido decreased • # of mounts increased • Time in collection room increased • Interest in tease mare decreased No “P” values were given

  17. Conclusion • Immunocastration IS an alternative to castration • Needs more research • May become the norm in the race and show horse industries • DEFINITELY WORTH LOOKING INTO

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