Abstract: OBJECTIVE: To examine the immunogenicity of an equine immunocontraceptive vaccine and its efficacy in controlling hormone-related behaviour. DESIGN: A total of 24 mares at two sites in Australia were vaccinated with an immunocontraceptive vaccine comprising gonadotrophin releasing hormone (GnRH) conjugated to a carrier protein in immunostimulating complex as an adjuvant. Twelve animals at each site received a placebo of adjuvant alone and served as controls for seasonal oestrus, hormonal and behaviour patterns. Animals were observed for injection site reactions, ovarian and follicular activity, and serum levels of antibody, 17beta-oestradiol and progesterone in the weeks following vaccination. Mares were also examined for oestrous behaviour by teasing with a stallion. RESULTS: All mares responded to vaccination. Two weeks following the second vaccination there was a peak in antibody response to GnRH that declined gradually over the following weeks. Commensurate with the elevated anti-GnRH antibody there was a marked effect on ovarian activity with a reduction in 17beta-oestradiol and progesterone levels in the 24 vaccinated mares. There was also a reduction of oestrus-related behaviour as determined by a teaser stallion. This effect lasted a minimum of 3 months and correlated with the initial level of antibody response. CONCLUSION: Following a conventional two-dose immunisation regime this commercially available equine immunocontraceptive vaccine was effective at inhibiting oestrous behaviour for at least 3 months. This vaccine has a high level of safety since there were no significant local reactions nor were there any adverse systemic responses to vaccination.

Abstract: REASONS FOR PERFORMING STUDY: There is limited knowledge available of factors influencing response to treatments of the DIP-joint in horses with lameness responding to diagnostic analgesia of the DIP-joint. For this reason a multivariable statistical analysis was performed. HYPOTHESIS: Horses with lameness reduced by > or = 75% 10 min after intra-articular analgesia of the DIP-joint, can be treated successfully by intra-articular medication of the joint. Multiple factors influence the response to treatment. METHODS: The study was performed retrospectively based on clinical records of horses treated with either polysulphated glycosaminoglycan (PSGAG) or methylprednisolone acetate (MPA) in the DIP-joint between January 1996 and January 2003. Information was collected from clinical records and from the owners of the horses via a detailed questionnaire, in which they described their perception of the outcome a minimum of one year after treatment. Allocation of the horses to the 2 treatment groups was done mainly because of a change in treatment policy. In Regime A all horses received 3 intra-articular injections of PSGAG approximately 8 days apart, whereas in Regime B all horses received a single intra-articular injection of MPA as a first treatment. If the horse did not improve sufficiently to return to work by 4 weeks, a series of 3 intra-articular PSGAG injections was administered. RESULTS: Of the horses receiving Regime A, 67% had a successful outcome, compared with 46% of the group receiving Regime B. A significantly better result was obtained in dressage horses than in jumping horses (eventing and showjumping). Other variables such as age, duration of lameness, distribution of lameness, degree of lameness, response to DIP-joint analgesia and radiographic observations were also associated with success of treatment. CONCLUSIONS AND POTENTIAL RELEVANCE: There is a rationale for using either PSGAG or MPA intra-articularly in the treatment of lameness, reduced > or = 75% within 10 min of analgesia of the DIP-joint.