In 2001, an international surveillance initiative was established, utilising a validated larval development inhibition assay to track the susceptibility of cat flea isolates to imidacloprid. In 2009, an Australian node was incorporated into the programme, joining laboratories in the United States and Europe. Field isolates of Ctenocephalides felis eggs were submitted to participating laboratories and, where egg quantity and quality was sufficient, were placed in the imidacloprid discriminating dose bioassay for evaluation. Between 2002 and 2012, a total of 2,307 cat flea isolates were received across all sites; 1,685 submissions (73 %) were suitable for placement into the bioassay. In the Northern Hemisphere, isolate submission rate was influenced by season, with highest numbers submitted between June and October. In Australia, pets with flea infestations could be sourced year-round, and submission rate was largely influenced by programme factors and not climate. A total of 1,367 valid assays were performed between 2002 and 2012 (assay validity data was not recorded in 2001); adult flea emergence 5 % or greater at 3 ppm imidacloprid was observed in 38 of these assays (2.8 %). For these isolates that reached the threshold for further investigation, re-conduct of the assay using either a repeat challenge dose of 3 ppm of imidacloprid or a dose response probit analysis confirmed their susceptibility to imidacloprid. From 2009 to 2012, the Australian node performed valid assays on 97 field isolates from a total of 136 submissions, with no adult emergence observed at the 3-ppm imidacloprid discriminating dose. In addition to reviewing the data generated by this twelve-year initiative, this paper discusses lessons learned from the coordination and evolution of a complex project across geographically dispersed laboratories on three continents.

Three randomised, blinded and placebo-controlled laboratory studies were conducted to evaluate the efficacy of emodepside plus toltrazuril suspension (Procox® suspension for dogs) against Isospora canis and Isospora ohioensis-complex. Unweaned puppies were experimentally infected with sporulated oocysts of I. canis and/or I. ohioensis-complex. In each study, one group was treated during prepatency (2 or 4 days post infection) while dogs in the second group were treated individually after the onset of oocyst excretion of the respective coccidia species. The dogs were treated with the minimum therapeutic dose of 0.45 mg emodepside and 9 mg toltrazuril per kg body weight. Daily faecal oocyst counts from both groups were compared to placebotreated control groups to determine efficacy. Dogs treated during prepatent I. canis or I. ohioensis-complex infection showed significantly lower oocyst counts for up to 12 days compared to the control group. Oocyst counts were reduced by 90.2 – 100 % while the control groups continued to exhibit an adequate infection, except for one study where efficacy against prepatent I. canis infection faded 13 days after treatment. Following treatment of patent I. canis or I. ohioensis-complex infections, significantly lowered oocyst counts were observed for up to 9 days compared to the control group. Faecal oocyst counts were reduced by 91.5 – 100 %. In all three studies the number of days with diarrhoea was significantly lower when dogs were treated during prepatent Isospora spp. infection compared to the control groups. No adverse drug reactions were observed during the studies. In conclusion, the studies demonstrated that emodepside plus toltrazuril suspension is an efficient coccidiocide for dogs.

The efficacy of emodepside plus toltrazuril (Pro-and between 4 and 655 worms for hookworms. The cox® oral suspension for dogs) against different studies demonstrated 100 % efficacy of emodepside/ species of gastrointestinal nematodes (Toxocara toltrazuril suspension against mature adult, ≥94.7% canis, Ancylostoma caninum, Uncinaria steno-efficacy against immature adult and 99.3 % efficacy cephala) was evaluated in nine randomised, against the L4 larval stage of T. canis. The efficacy blinded and placebo-controlled laboratory studies against mature adult A. caninum was ≥ 99.5 % and in naturally or experimentally infected dogs. The the efficacy against mature adult U. stenocephala product was used at the proposed minimum dose was 100 %. All differences between treatment and of 0.45 mg emodepside and 9 mg toltrazuril per control groups were statistically significant and no kg body weight. Efficacy was calculated based on gender effect was found. It can be concluded that the worm counts after necropsy. Worm burdens in the control dogs ranged between 0 and 409 worms of the respective stage for T. canis and between 4 and 655 worms for hookworms. The studies demonstrated 100 % efficacy of emodepside/toltrazuril suspension against mature adult, ≥ 94.7 % efficacy against immature adult and 99.3 % efficacy against the L4 larval stage of T. canis. The efficacy against mature adult A. caninum was ≥ 99.5 % and the efficacy against mature adult U. stenocephala was 100 %. All differences between treatment and control groups were statistically significant and no gender effect was found. It can be concluded that the emodepside/toltrazuril suspension represents a safe and highly effective product in dogs with nematode (T. canis, hookworms) infection.

A flea larval bioassay was developed by an international team of scientists to monitor the susceptibility of fleas (Ctenocephalides felis) to imidacloprid (Advantage, Bayer HealthCare). The assay was validated using laboratory and field isolates of C. felis. Flea eggs representing different field isolates of C. felis were collected by veterinarians in the United States, United Kingdom, and Germany. Of the 972 flea isolates obtained during the 5-year study, 768 contained sufficient numbers of eggs to conduct the larval bioassay. Greater than 5% survival occurred for only six of the field isolates evaluated. Further evaluation and analysis of these isolates demonstrated that they did not differ significantly in their susceptibility to imidacloprid from the reference strains used to develop the assay. Collections of field flea isolates will continue in an attempt to detect and document any change in the susceptibility of field flea populations to imidacloprid.