Background: The safety and efficacy of a new spot-on formulation of selamectin plus sarolaner were evaluated for the treatment and control of natural flea infestations on cats in two non-randomised, multi-centre clinical trials conducted in 8 different locations in Queensland, Australia. Methods: One hundred and four cats from 65 different households were enrolled across the two studies. Demographic characteristics of cats in the two studies were similar. The new spot-on formulation of selamectin and sarolaner was administered topically once a month for 3 consecutive months at a minimum dosage of 6 mg/kg selamectin (dose range 6-12 mg/kg) plus 1 mg/kg sarolaner (dose range 1-2 mg/kg). Cats were dosed on Days 0 (pre-treatment), 30 and 60 and physical examinations and flea counts were conducted on Days 0, 30, 60 and 90. Efficacy assessments were based on the percentage reduction in live flea counts post-treatment compared to Day 0. Results: In Study A, at enrolment, primary cats had flea counts ranging from 6 to 107 (arithmetic mean 21.0). The selamectin and sarolaner spot-on formulation resulted in arithmetic mean efficacy of 98.0%, 100% and 100% on Days 30, 60 and 90, respectively. In Study B, at enrolment, primary cats had flea counts ranging from 6 to 22 (arithmetic mean 10.0). The selamectin and sarolaner spot-on formulation resulted in arithmetic mean efficacy of 99.7%, 100% and 100% on Days 30, 60 and 90, respectively. Conclusions: The new spot-on formulation of selamectin plus sarolaner topically administered at monthly intervals at the minimum dosage of 6.0 mg/kg selamectin and 1.0 mg/kg sarolaner was safe and highly effective against natural infestations of fleas under a range of geographical conditions, representative of both tropical and subtropical regions of Australia.

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.