The ticks and worms in this country do not carry the same diseases as those found abroad.
I took the info below from the DEFRA site.
Leishmaniasis
Leishmaniasis is caused by a protozoan (Leishmania sp.), which is spread between animals by sandflies. The disease is present in Europe, the Middle East and many tropical countries. The organism can cause disease in people. Affected animals may lose weight, develop skin lesions and swollen lymph nodes, become lame and have recurring fevers.
Babesiosis
Babesiosis (or Redwater) is a disease of cattle and other mammals, caused by the protozoan parasites Babesia bovis, B. bigemina, B.divergens and others. The protozoan develops inside the red blood cells of affected animals. Different species of the organism affect different animals. The organism is transmitted between animals by ticks but can also be spread by contaminated instruments or needles. Babesiosis occurs worldwide and bovine redwater is constantly present in some areas of the UK. In Europe, particularly in Southern France, the infection occurs in dogs and there is a possibility that dogs from the UK, on holiday with their owners in Europe, may return home with the infection. Signs of disease may include a fever, loss of appetite, the passage of red / brown urine , anaemia and weakness. Recovered animals are immune to reinfection by the same species of organism. However the parasite may persist in the blood for some years causing the disease to reappear in the same animal.
Ehrlichiosis
Ehrlichiosis is caused by a bacterium called rickettsia that can infect the blood cells of several species including dogs, horses and people. It is transmitted by ticks. The disease occurs in North Africa and in several European countries. Clinical signs vary but include fever, loss of appetite , anaemia, stiffness and reluctance to move. Prolonged bleeding may be seen.
Dirofilariasis (Heartworm Disease)
Infection by a parasitic worm called Dirofilaria immitis may result in heartworm disease. The adult worms live in the heart and blood vessels. Dogs are most commonly affected, but the worms can also infect cats and ferrets. The intermediate stage of the worm, called the larva, is transmitted between animals by mosquitoes in hot countries including Spain and France. Clinical signs vary but may include coughing, breathlessness and intolerance to exercise and can lead to death.
All of these can have severe consequences in your animal; some can also cause disease in humans.
When I was a vet nurse we were taught that it is possible for a wormed animal to become infected with more worms (including tapeworms and roundworms) 48 hours after the wormer is given. The reason we don't worm weekly or monthly is that the tapeworm and roundworms that we have in this country do not carry these terrible diseases. It is sufficient here, usually, to worm every 3-6 months, depending on the dog's lifestyle, in order to prevent a build up of parasites.
We stop off in a little town called Ardres to get our dog treated and so avoid the Calais vets :wink:
When I asked my vet, and former boss, to be brutally honest in his opinion of travelling with dogs under PETS he said he wouldn't risk it 8O