Metabolism of norethisterone in the greyhound

Effects of norethisterone acetate on the performance of female racing Greyhounds

A comparison between the performance of spayed female racing Greyhounds and those suppressed with norethisterone acetate (NTA) was made. Previous work by the author has shown that the racing performance of spayed bitches is the same as that of entire bitches in anoestrus, i.e. spaying is just a permanent anoestrus. The aim was to assess any performance difference between suppression and anoestrus, and thus to determine the effect of norethisterone acetate on race performance. The study was designed as a retrospective case-control. Raceform data was obtained for female racing Greyhounds which had raced, and which were either spayed or suppressed with norethisterone acetate. Analysis showed that suppressed bitches run on average 0.049 to 0.061 s slower over 480 m (centralised models). Since endogenous progesterone (P4) has been linked with reduced race performance, it is logical that progesterone analogues like NTA should have a similar effect. It is likely that the depression in performance is dose-related, but not quantifiable with the current dataset.

Investigations into the analysis of intact drug conjugates in animal sport doping control - Development and assessment of a rapid and economical approach for screening greyhound urine

Animal sport doping control laboratories are constantly reviewing ways in which they can improve their service offering whilst ensuring that they remain economically viable. This paper describes the development and assessment of a rapid and economical method for the detection of intact glucuronide conjugates of three anabolic steroids and their metabolites along with three corticosteroids in canine urine. The analysis of intact drug conjugates for animal sport doping control is generally not performed routinely as it presents a number of analytical challenges, not least of which is the lack of availability of appropriate reference standards. Here, we report the development of a UHPLC-MS/MS method using APCI in the negative ion mode for the detection of intact phase II conjugates, including the importance of in vitro incubations in order to provide appropriate reference materials. Cross-validation of the developed method demonstrated that the detection capability of the intact phase II conjugates of stanozolol, boldenone, nandrolone, and their metabolites along with the corticosteroids dexamethasone and methylprednisolone was equivalent to that achieved in routine race-day screens. The new process has been in operation for approximately 2 years and has been used to analyze in excess of 13500 canine urine samples, resulting in a number of positive screening findings. To the best of our knowledge, this is the first reported use of a routine screen for intact drug conjugates within animal sport doping control.