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Ticks of dogs

his section is devoted to the ticks that are commonly encountered on dogs.

Haemaphysalis elliptica – southern African yellow dog tick



Haemaphysalis elliptica – southern African yellow dog tick

For many years this tick was referred to as Haemaphysalis leachi, with which it had been lumped. We now know that it is a valid species in its own right and that all previous records of H. leachi in South Africa actually refer to H. elliptica.
The hypostome and palps are short. The second segment of the palps is extended laterally giving the capitulum a triangular appearance. The basis capituli has well-developed posterior processes (cornua). The scutum is yellow in colour and is covered with numerous small punctations and festoons are present. Eyes are absent. There are no adanal plates in the males.

Adults are found on dogs, cats and larger wild carnivores, particularly the large wild felids. Larvae and nymphs infest rodents. Adults attach to the head, neck and shoulders, but in severe infestations they are present over the entire body.
Haemaphysalis elliptica is present in the eastern part of the country from East London through KwaZulu-Natal to the Zimbabwean border, as well as the Provinces of Gauteng, North West Province, Mpumalanga, Limpopo and north-eastern Free State in South Africa. It is also present in numerous large foci in the Eastern and Western Cape Provinces. The ticks prefer high rainfall, but may occur wherever the rodent hosts for the immature stages are present. Because the hosts of the immature stages are rodents, this tick generally infests dogs in large domestic plots, small-holdings and farms.

Haemaphysalis elliptica is a three-host tick. The female feeds for 1 to 2 weeks, expands slowly initially but engorges rapidly on the last day. Female ticks lay about 5000 eggs within 14 days of detaching from the host. The eggs hatch in 1 to 4 months. The larvae and nymphs usually infest common murid rodents but may also be found on dogs. 
Adults are present throughout the year with peak numbers from winter, spring to late summer. Haemaphysalis elliptica is the vector of Babesia rossi, the cause of canine babesiosis.

Rhipicephalus gertrudae

The conscutum and scutum are dark or reddish-brown and very heavily punctate. Posterior grooves are absent or very indistinct.  The caudal process is bluntly rounded in engorged males, and the adanal plates are large and almost kidney-shaped.  The posterior margin of the female scutum is usually smoothly rounded and the external margin of the broad cervical fields is clearly demarcated by irregular rows of punctations. 



Rhipicephalus gertrudae

Adults occur on dogs, cats, sheep and antelopes (e.g. eland). Immature stages are found on rodents. The adults attach to the head and shoulders of dogs. Because the hosts of the immature stages are rodents, this tick generally infests dogs kept on large domestic plots, small-holdings and farms. It is a three-host tick and the adults are present from late winter to early summer.

 It replaces R. simus in the Western and Northern Cape Provinces, western Free State.

Rhipicephalus sanguineus – the kennel tick

The conscutum and scutum are yellowish to reddish-brown and, apart from a variable number of punctations, often appears smooth.  The eyes are distinct and slightly convex. The marginal grooves in the male are sharply defined. The posterior grooves on the conscutum of the male may be well-defined or inconspicuous.  The bodywall of the male has a salmon-pink colour and when engorged extends beyond the conscutum.  The basis capituli of the female has broad lateral angles, and the cervical fields are slightly depressed and scalpel-shaped.

Dogs are the preferred, if not the only hosts, for all stages of development. Larvae are found particularly on the stomach and sides, nymphs on the ears and shoulders, and adults on the ears, neck and shoulders of dogs.  Adults and nymphs may also be present between the toes.

Its distribution is world-wide between 50°N and 35°S.  In South Africa it is found particularly in the warm and moist areas, it also occurs in dry areas but not in the desert-like conditions in the west of the country. The immediate distribution of its free-living stages is confined to kennels, domestic dwellings and other human-made structures. This tick is well-adapted to living in kennels and houses. Except when it is present on dogs it does not occur outside of these structures.

Rhipicephalus sanguineus is a three-host tick. The engorged female detaches and lays 3000 to 5000 eggs within 1 to 8 weeks. These eggs hatch in 3 to 8 weeks. The larvae engorge in 3 to 8 days and moult in 3 to 4 weeks. The nymphs engorge in 4 to 10 days and moult in 3 to 26 weeks. The adults may engorge in 7 days but the female can stay on the dog for 3 weeks and the male for considerably longer. The life cycle can be completed in 10 weeks under ideal conditions. In warm temperate and summer rainfall areas all stages are found on dogs from October to May.

nfestation over-winters as the pre-moulted nymph stage and possibly as engorged females. More than one life cycle per year is possible. The females may lay their eggs under the dogs' bedding or in cracks and crevices or they may climb up the walls and lay eggs in cracks and crevices in the walls.  The larvae and nymphs usually moult in the same sites as the females lay their eggs.  Dogs that are tied up or caged may become heavily infested. In artificially heated houses the life cycle may continue during winter.

Rhipicephalus sanguineus is the vector of Ehrlichia canis, the cause of canine ehrlichiosis or tropical pancytopaenia in dogs.

Rhipicephalus simus - Glossy brown tick

The conscutum and scutum are shiny and dark or reddish-brown. There are four definite longitudinal rows of large punctations referred to as the “simus” pattern on the conscutum of the male, on which there are also numerous small to minute punctations. Posterior grooves are absent or very indistinct. The caudal process is bluntly rounded in engorged males, and the adanal plates are large and almost kidney-shaped. The posterior margin of the female scutum is usually smoothly rounded and the external margin of the broad cervical fields is clearly demarcated by irregualar rows of punctuations. The shape of the female genital aperture is a truncated U-shape, diverging anteriorly.
Adult ticks infest dogs, cats, cattle, sheep, goats, horses, large carnivores (e.g. lions), zebras, warthogs, and rhinoceroses. Because the hosts of the immature stages are rodents, this tick generally infests dogs kept on large domestic plots, small-holdings and farms. The adults are found on the head and shoulders of dogs.

Rhipicephalus simus is widespread in the moister eastern regions of southern Africa, but is never very numerous. It is a three-host tick of which the adults are present in summer, larvae in autumn to winter on their rodent hosts, and the nymphs from winter to spring on rodents.

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