Ticks on dogs and cats

While brushing down their pet spaniel following a long summer walk, the owners discovered a pale grey lump hanging from its head just below its eye. This was an engorged and deeply embedded feeding tick; the mouthparts were firmly attached and not visibly obvious as they were deeply buried into the skin, but the tick's swollen abdomen was clearly exposed (Figure 1). The worried owner consulted their local veterinary surgery for advice. There is good evidence that ticks are becoming both more abundant and more widespread (Scharlemann et al, 2008). The number of pets being affected is increasing and the number of animals appearing in the veterinary surgery carrying ticks is likely to grow.

Ticks are blood feeding parasites. Their exact classification is debated but they are usually placed within their own superorder (Parasitiformes) and order (Metastigmata/Ixodida) within the class Arachnida and subclass Acari (Baker, 1999; Beccaloni, 2009). Ticks are superbly adapted anatomically to their parasitic lifestyle. The standard ‘classic’ physical description is that provided by Arthur (1963); more recent descriptions are provided by Sonnenshine (1991) and Hillyard (1996). Their flattened body allows them to nestle easily between fur directly to the skin. The four pairs of legs often have sharp hooks on their inner sides, ‘spurs’, which aid attachment to the host. Ticks have a small hardened shield, the ‘scutum’, which in males covers the entire dorsal side. Females have a smaller scutum, thus allowing the body to expand more easily. Females take much larger blood meals than males. The mouthparts are highly specialised; sensory ‘palps’ feel for a suitable bite location, scissor like ‘chelicerae’ make the initial cut, and a sharp needle like tube, the ‘hypostome’, sucks up the blood (Richter et al, 2013).