BACKGROUND : Rhipicephalus sanguineus (sensu lato) is a vector of canine babesiosis, anaplasmosis and ehrlichiosis.
In order to reduce the chance of transmission of these diseases, an ectoparasiticide should rapidly repel or kill new
infestations with this tick. The primary objective of the present study was to evaluate the treatment and preventive
acaricidal efficacy of Vectra® 3D (54.45 mg/ml of dinotefuran, 396.88 mg/ml of permethrin and 4.84 mg/ml of
pyriproxyfen) against R. sanguineus (s.l.) measured at 2, 8, and 48 h after treatment and weekly re-infestation.
METHODS : Twenty-four dogs were each infested with 50 adult R. sanguineus (s.l.) on Day -7 and allocated to three
groups (n = 8) based on tick counts: an untreated control group (Group 1), and two groups (Groups 2 and 3) treated
with Vectra®3D. The dogs in each group were infested with 50 ticks on Day -2. Vectra®3D was administered topically
to the dogs on Day 0. Ticks were counted, in situ at 2 and 8 h after treatment on dogs in Groups 1 and 3. Group 3 was
then withdrawn from the study and ticks were counted and removed from the dogs in Groups 1 and 2, 48 h after
treatment. On Days 7, 14, 21, 28, 35 and 42, the dogs in Groups 1 and 2 were re-infested with 50 ticks, which were
then counted in situ at 2 and 8 h, and counted and removed at 48 h after re-infestation.
RESULTS : Ticks from the initial infestation were visually unaffected by 2 and 8 h after treatment. However, by 2 h after
weekly re-infestation the arithmetic mean (AM) efficacy of Vectra® 3D from Days 7 through 28 ranged from 61.1 to 78.8 %,
falling to 60.1 and 47.4 % on Days 35 and 42 respectively. By 8 h after weekly re-infestation, the AM efficacy ranged from
89.1 to 97.4 % falling to 81.4 and 69.8 % on Days 35 and 42 respectively. The AM efficacy 48 h after treatment after the
initial infestation was 22.9 % but after weekly re-infestation the efficacy at 48 h ranged from89.1 to 100.0 %, falling to 86.0
and 81.1 % on Days 35 and 42 respectively.
CONCLUSION : Vectra® 3D demonstrated significant efficacy against new infestations of adult R. sanguineus (s.l.) ticks within
2 h of infestation as compared to the untreated control group and achieved over 89.1 % efficacy within 8 h of infestation
for up to 4 weeks after administration. These results indicate that Vectra® 3D has a rapid and significant efficacy against
new infestations of adult R. sanguineus (s.l.) ticks and should therefore be considered as part of a strategy against
important vector-borne diseases in dogs.