A blood-sucking tick from mainland Europe has been found in the UK for the first time and is raising the chances of human health being damaged by parasites.
Dermacentor reticulates is thought to have been brought over the water by climate change, according to researchers at the University of Bristol.
The scientists also said the number of dogs infested with every parasite species is much bigger than they had originally suspected. They said this might mean the risk of disease carried by the ticks among both humans and animals is increasing.
Richard Wall, who runs the university's veterinary parasitology and ecology group which did the research, said: "This is an important study because the results suggest that the risk of tick infestation is far higher in dogs than was previously thought."
Professor Wall went on: "This has serious implications for the incidence of tick-borne disease.
"The study also confirms that a non-native species of tick, which is also a major disease vector in Europe, is now established in southern England."
Dog ticks can be infected with several tick-borne diseases, such as Lyme disease which can damage human heart and nervous systems.
The research appeared in the Medical and Veterinary Entomology journal. The group analysed 3,500 dogs that had been treated by 173 vets across the UK and found that at any one time 14.9% of dogs are infested with ticks.