Two complementary methods to control gonadotropin-releasing hormone vaccination (Improvac®) misuse in horseracing: Enzyme-linked immunosorbent assay test in plasma and steroidomics in urine.

This research investigates the misuse of a pig immunological castration vaccine, Improvac®, in horse racing, offering two methods of detection: an enzyme-linked immunosorbent assay (ELISA) in plasma, and a steroidomic approach in urine. Male horses treated with Improvac® produced substantial hormonal changes linked to behavioural changes, prompting a need for effective screening methods.

Background

• The researchers conducted this study in response to concerns that the vaccine Improvac®, originally created for immunological castration of male pigs, may be misused in the horse racing industry to induce behavioural modifications.
• Immunological castration is disallowed in racing codes due to its potential changes in behaviour and physical state. It acts via a vaccination against the GnRH hormone which inhibits luteinizing hormone and follicle stimulating hormone — necessary for gonadal functions and subsequent physiological processes.

Study Method

• The study monitored four vaccinated male standardbreds. The treatment involved two intramuscular Improvac® injections over a span of 4 weeks.
• The team measured the total scrotal width to track the physical changes, and production of anti-GnRH antibodies to identify the immunological alterations.
• Findings displayed a noticeable decrease (37%) in the size of the scrotum, and presence of anti-GnRH antibodies up to 200 days post the initial injection.

Testing Methods

• The researchers developed an enzyme-linked immunosorbent assay (ELISA) after caprylic acid precipitation in plasma as a rapid and effective screening method.
• This was supplemented with a steroidomic approach in urine that identified the alteration in sexual status from the male group to the gelding/female group, based on ten endogenous compounds.

Significance

• The identification of Improvac® misuse has potential ramifications for athlete welfare and competitive integrity in horse racing.
• The two complementary methods proposed can provide a robust approach to routine screening for these hormonal and behavioural modifications.
• This offers an important deterrent and detection method to prevent the misuse of Improvac® within the industry.