Integrated control of ticks and fleas on dogs with particular reference to the prevention of vector-borne diseases

Because dogs are such loved companion animals, their health and wellbeing is of
great importance to their human companions. Moreover, controlling ticks and fleas
on dogs is also important in respect of the zoonotic risk that some of these parasites
pose to their human companions. Numerous products are available to veterinarians
and dog owners for controlling ticks and fleas. By comparing the efficacy of these
products, important information can be collected that will help the end-user to decide
on the most appropriate product.
It was hypothesized that the combination of different active substances and
alternative routes of administration using improved delivery systems, could enhance
the speed of kill as well as duration of efficacy of various compounds.
Moreover, if the speed of kill was rapid enough, these products could
potentially prevent infections with tick-borne and flea-borne pathogens.
Therefore the aim of the studies described in this thesis was to evaluate and
compare the efficacy of various classes of compounds, with different modes of action,
used for the control of tick and flea infestation on dogs. The efficacy of these
compounds was evaluated either separately, or administered in combination, using
different application modes, such as topical application, impregnated collars or oral
formulations. Moreover, the ability of several compounds to prevent transmission of
selected tick- and flea-borne pathogens was also assessed.
In Chapter 2 the efficacy of various compounds against Haemaphysalis
elliptica, Dermacentor reticulatus and Rhipicephalus sanguineus as well as Ctenocephalides
felis was evaluated on dogs in controlled laboratory studies.
In order to protect a dog from the detrimental effects of tick infestation pharmaceutical
products must not only be able to control ticks, but the onset of action
must be fast enough to prevent transmission of harmful tick-borne pathogens.
In Chapter 3 the ability of different compounds to prevent the transmission
of the tick-borne pathogen Babesia canis by Dermacentor reticulatus is evaluated in
controlled laboratory studies.
In Chapter 4 the ability of different compounds to prevent the transmission
of the tick-borne pathogen Ehrlichia canis by Rhipicephalus sanguineus is evaluated
in controlled laboratory studies. Moreover, the speed of transmission of E. canis
by infected R. sanguineus was evaluated and compared in vivo on dogs and in vitro
on artificial feeding membranes.
Finally, in addition to the immediate irritation that flea infestations cause
to dogs, fleas are also intermediate hosts of the metacestode stages of the cestode
Dipylidium caninum. In Chapter 5 the prophylactic effectiveness of a collar formulation
against infected fleas is evaluated and consequently also its ability to prevent
D. caninum infection in dogs.