These studies support the efficacy and safety of a single dose of Readyserve® injection for the suppression of the signs of oestrus in mares for 5-7 days.

Medication control in greyhound racing requires information from administration studies that measure drug levels in the urine as well as plasma, with time points that extend into the terminal phase of excretion. To characterize the plasma and the urinary pharmacokinetics of flunixin and enable regulatory advice for greyhound racing in respect of both medication and residue control limits, flunixin meglumine was administered intravenously on one occasion to six different greyhounds at the label dose of 1 mg/kg and the levels of flunixin were measured in plasma for up to 96 hr and in urine for up to 120 hr. Using the standard methodology for medication control, the irrelevant plasma concentration was determined as 1 ng/ml and the irrelevant urine concentration was determined as 30 ng/ml. This information can be used by regulators to determine a screening limit, detection time and a residue limit. The greyhounds with the highest average urine pH had far greater flunixin exposure compared with the greyhounds that had the lowest. This is entirely consistent with the extent of ionization predicted by the Henderson–Hasselbalch equation. This variability in the urine pharmacokinetics reduces with time, and at 72 hr postadministration, in the terminal phase, the variability in urine and plasma flunixin concentrations are similar and should not affect medication control.

The oral tablet formulation of butylscopolamine, which is available without prescription, is commonly used by trainers of racing greyhounds to treat functional urethral obstruction. As medication control of butylscopolamine is therefore required for such use to ensure the integrity of greyhound racing, an administration study was performed in six greyhounds to determine the pharmacokinetics of orally administered butylscopolamine. A single dose of one 10 mg butylscopolamine tablet was administered orally to simulate this use in greyhound racing. Blood, urine and faeces were collected at regular intervals from the greyhounds for up to 9 days and butylscopolamine concentrations determined. There was some, but very limited, absorption of butylscopolamine, with rapid elimination from plasma with a mean half-life of 2 hr. Urine concentrations initially declined in a similar manner to the plasma pharmacokinetics but then entered a much longer half-life of approximately 50 hr. Faecal concentrations declined to very low levels between 48 and 120 hr. The use of orally administered butylscopolamine for functional urethral obstruction in greyhounds is unjustified due to this very limited drug absorption. Medication control of butylscopolamine's antispasmodic effect on the digestive tract is possible by setting screening limits based on the urinary and faecal drug levels as determined in this study.

Dexamethasone, formulated as sodium phosphate and as phenylpropionate combined with sodium phosphate, was administered subcutaneously to six greyhounds. Plasma and urine were collected for up to 240 h and analysed with a limit of quantification (LOQ) of at least 100 pg/ml for dexamethasone. Dexamethasone, formulated as sodium phosphate, terminal half‐life was 10.4 h in plasma and approximately 16 h in urine, and at 96 h, plasma hydrocortisone concentrations returned to background with dexamethasone levels around the LOQ. Dexamethasone, formulated as phenylpropionate combined with sodium phosphate, terminal half‐life, was 25.6 h in plasma and approximately 26 h in urine, and at 96 h, plasma hydrocortisone concentrations returned to background with dexamethasone levels in three of the six greyhounds around the LOQ. Critical assessment of the pharmacokinetic and pharmacodynamic data indicated how it might be utilized for medication control in racing greyhounds.