Ticks are blood-sucking ectoparasites. Their hosts include all animals (including humans) and their numbers and geographical spread in the UK is increasing. This is likely to be due to a number of factors including a warmer climate, environmental schemes increasing tick habitats, and sheep being dipped less frequently.
There are more than 20 species of ticks but the most common sheep tick (Ixodes ricinus) can transmit louping ill, tickborne fever and tick pyaemia. All ticks can also transmit Lyme disease (caused by Borrelia burgdorferi) to humans, dogs and horses. Hill flocks are generally most at risk because ticks favour the dense vegetation and warm, humid conditions found in the uplands. However, ticks are also often found on lower lying areas of rougher grazing, field boundaries etc. Generally there are two peaks of tick activity, in the spring and in the late summer/autumn.
Ixodes ricinus is a ‘three-host’ tick with larvae, nymphs and adults feeding on different hosts. Larvae and nymphs prefers small to medium-sized animals and adults tend to feed on larger animals, such as sheep. This species of tick feeds on a broad range of mammals, birds, reptiles and is of growing concern with regard to it biting humans.
Diseases spread by ticks
Apart from louping ill, where vaccination can play a role, the main way to control diseases transmitted by ticks is to treat at risk sheep with an acaricide treatment. The blowfly option table at the bottom of this page includes a column for ticks. Farms at risk of ticks need a plan that is specific to their situation, including the choice and timing of control products, so ask your vet or animal health advisor for advice. Always read the manufacturer's instructions before using a control product. Withdrawal periods are subject to change and it is the user’s responsibility to ensure withdrawal period is adhered to.
Particular care is required when new sheep are brought onto a farm with tick areas from a farm or area that is tick-free. Even adult sheep are at risk in these circumstances so they must be introduced well ahead of the breeding season and protected from ticks using an acaricide product.