Differences in the susceptibility of two breeds of dogs, English cocker spaniel and beagle, to Rhipicephalus sanguineus (Acari: Ixodidae)

The objective of this study was to evaluate differences in susceptibility to Rhipicephalus sanguineus (Latreille) of two breeds of dogs: English cocker spaniel and beagle. Three artificial infestations of ticks using a capsule on the back of the dogs were carried out at 15 day intervals. Six dogs of each breed were infested with 100 larvae, 50 nymphs and 20 adults (10 males and 10 females). Every 2 days, the ticks on the dogs were evaluated and the engorged ones counted and collected. The ticks were stored in climatic chambers and inspected every two days for 14 days. The following parameters were recorded: number of engorged ticks, engorgement period, percentage of ecdysis, female weight, conversion of body weight to eggs and larval hatchability. In the ticks recovered from the cocker spaniel, higher percentages of ecdysis of larvae and nymphs, greater number of adults attached and engorged and higher reproductive performance of the females (conversion to eggs and hatchability) were observed. The period of engorgement, number of engorged nymphs and weight of the females did not differ much by breed, but more larvae were attached and engorged in the beagle. In the two breeds, an effect of the successive infestations on the number of engorged larvae and nymphs was observed, which demonstrates the development of a response to the infestation in these stages. However, the percentage of ecdysis and the conversion to eggs was affected only in the more resistant beagles. Based on what was presented, it can be concluded that the animals of the race English cocker spaniel are more susceptible to R. sanguineus than the beagles and that the infestations affect the development of the tick, especially in resistant individuals.