A dog has died after contracting a tropical disease which can be passed on to humans.
Leishmaniasis is responsible for 40,000 deaths annually, mainly among the poorest communities in the world.
It is caused by a parasite spread through the bite of infected female sand flies, and can lead to lesions, weight loss and kidney failure.
Previously cases of the killer disease had involved breeding programmes, blood transfusions or travel to an affected area.
But vets have issued a warning after leishmaniasis was passed between two UK dogs for the first time.
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In Hertfordshire a dog was put down after three weeks of weight loss, vomiting and diarrhoea caused by severe leishmaniasis.
The pet, which had been imported from Spain, was taken to the Queen Mother Hospital for Animals in Hatfield where the decision was taken to put it down.
And now, six months later, a three year old neutered male shih tzu cross from the same household has been diagnosed with the disease.
The dog had been with its owner since being a puppy and had none of the known risk factors. Is is believed to have contracted the disease through dog to dog transmission.
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In medical journal Vet Record, Dr Myles McKenna and colleagues said: "It is important to take note of this first reported case of likely dog-to-dog transmission of Leishmania infantum in the UK.
"Historically we had considered this to be a condition affecting dogs with a travel history to areas where Leishmania infantum is endemic.
"Dog-to-dog transmission in non-endemic areas has previously been reported, for example in the USA, but this case serves as a reminder to UK veterinary surgeons that we must be vigilant for conditions such as Leishmaniasis in non-travelled dogs and that alternative transmission mechanisms do exist."
The case follows an English pointer diagnosed with the disease despite never leaving Essex.
The dog was not in contact with another infected dog, but it is believed its owners had brought back infected sand flies in transport, luggage or clothing after living in Spain - without their pet.
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Dr Myles McKenna said: "In an era of increased foreign travel of dogs and increased importation of dogs to the UK, it is likely that the number of dogs positive for leishmaniasis will continue to increase.
"Infected dogs may present a risk to other dogs, even in the absence of natural vectors, as direct transmission between dogs is possible."
Ian Wright, a veterinary surgeon and the UK and Ireland head of the non-profit group of European vets specialising in parasitology, said: "This case demonstrates it cannot be assumed that because a dog has no history of travel, leishmaniosis can be ruled out.
"It also serves as a reminder that we should not be complacent about the risk of leishmaniosis establishing in the UK, even in the current absence of the sand fly vector."
What is Leishmaniasis?
Leishmaniasis is the diseased condition brought about by the parasite Leishmania. It results in two types of diseases in dogs: a cutaneous (skin) reaction and a visceral (abdominal organ) reaction, also known as black fever. This is the most severe form of leishmaniasis.
The infection is acquired when sandflies transmit parasites into the skin of a host. The incubation period from infection to symptoms is generally between one month to several years. In dogs, it invariably spreads throughout the body to most organs and kidney failure is the most common cause of death.
