Ticks were found on almost one in three dogs during random checks of pets in the largest survey of its kind in the UK.
Researchers found that the tiny, spider-like creatures were present all across the country, with the likelihood of a dog picking one up equal in both rural and urban areas.
They pose a risk as they can transmit bacteria that cause diseases such as Lyme disease, which can lead to very serious conditions including meningitis or heart failure if left untreated, even proving fatal.
Scientists from the Big Tick Project at the University of Bristol examined a study of 15,000 dogs from across the UK last year, the BBC said.
If found that 31% of these checked at random when taken to the vet was carrying a tick.
Highest risk areas were the South West, East Anglia and Scotland.
Professor Richard Wall, who led the project, said: “The work that we have carried out shows that ticks are extremely widely dispersed. The records that we have got appear to show that we have had an increase in tick numbers right across the country.
“What we are primarily concerned about is the diseases that ticks carry. In the UK, we have relatively low rates of the prevalence of these pathogens at the moment and, in contrast, in continental Europe they have much higher rates of disease.
“As there seems to be a rise in tick numbers, we need to be concerned and be aware of the potential for increasing problems.”
Conservationist Chris Packham, who is taking part in the project, said it had been “tremendously significant” work which had revealed “some very shocking and surprising things about the distribution, the population and potential that ticks have to give diseases to our pets and ourselves”.
He said pet owners should be aware of risks in woodlands and areas of long grass, but said urban areas were also affected.
Ticks and the diseases they carry have become a rapidly growing problem across the UK, according to the project, with the distribution of ticks estimated to have expanded by 17% across Great Britain in the last decade.
The growing threat is thought to be partly down to the wet, warm winters the UK has had in recent years., meaning ticks can start feeding earlier and for longer throughout the year.
Ticks do not jump or fly, but wait until an animal or person brushes past to climb on. They then bite to attach to the skin and start to feed on the blood.
According to Public Health England, it is estimated that there are 2,000 to 3,000 new confirmed cases of Lyme disease in England and Wales each year, although not all cases are confirmed by laboratory testing, the BBC said. Around 15% of cases are in people returning from overseas.
