First known case of dog-to-dog transmission of leishmaniosis recorded in the UK

Leishmaniosis (also sometimes known as leishmaniasis) is an infectious health condition that can affect dogs, and that is spread by sand fly bites. This is a canine health condition that many dog owners have never even heard of, because it isn’t one that tends to be commonly found within the UK.

This is due to the fact that sand flies aren’t native to the UK and so leishmaniosis is not one of the more acute threats to the health of UK dogs, although there have still been several cases of leishmaniosis in dogs in the UK to date. These have resulted from dogs that have travelled abroad returning home on their pet passports after having already contracted the infection somewhere else, and in one case, sand fly eggs and larvae have been traced as having been carried back to the UK on clothing and luggage, later hatching here and infecting the family dog after their return.

Even when a dog does return to the UK with leishmaniosis, up until now, this was not considered to pose an infection risk to other dogs. However, the Royal Veterinary College in London recently reported that one of its clinical training residents has formally diagnosed the first known and confirmed case of dog-to-dog transmission of leishmaniosis in the UK, in a dog that had not travelled outside of the UK and so, could not have been exposed to the infection elsewhere.

In this article we will provide a short explanation of leishmaniosis in dogs, how it is contracted, and what the report of a known case of dog-to-dog transmission of the illness means for other dog owners in the UK.

Read on to find out more about leishmaniosis and dog-to-dog transmission.

What is leishmaniosis?

Leishmaniosis is an infectious disease caused by a parasite called Leishmania, which can result in two quite different immune responses in different dogs.

Some dogs will develop an adverse skin reaction as a result of infection, whilst others have a systemic response to the threat, involving the skin and also the abdominal organs, resulting in an acute and serious type of leishmaniosis called black fever, which is very severe and unfortunately, the more common canine reaction of the two.

Dogs can develop leishmaniosis infection when they come into contact with sand flies, which may infect the skin of a host dog. However, this can be a really hard disease to diagnose in dogs, not least because it is so uncommon in the UK and so, not the first thing that comes to mind when considering differential diagnosis, even in dogs that have recently been outside of the UK.

The incubation period for leishmaniosis in dogs can be really variable too, with symptoms rarely developing within the first month after infection, and sometimes taking several years, to further complicate matters.

Generally, the infection becomes systemic when it does develop symptoms and in a short period of time, and the condition is very serious for most dogs, and death often occurs as the result of kidney failure and major organ shutdown.

Most dogs that have a systemic reaction will also have a skin reaction, although a small proportion of affected dogs display skin symptoms only, without later progression to organ damage.

How is leishmaniosis transmitted?

Up until very recently, the suggestion that leishmaniosis could be transmitted from one dog to another rather than by means of direct infection with sand flies as the vector wasn’t one that was given a lot of gravitas.

Whilst there have been recorded incidences in countries outside of the UK of dogs catching leishmaniosis from each other due to unusual or unique situations such as a blood transfusion taken from an infected dog and a dog-to-dog bite involving an infected dog, there has never before been a recorded case of dog-to-dog transmission within the UK, nor one without a unique known trigger such as those mentioned.

The most common form of transmission to dogs is by means of sand flies, and it is worth remembering that sand fly eggs and larvae can also be carried on clothing and skin, and so brought back to the UK, where they may hatch and affect the family dog later on.

Why and how the recorded case of dog-to-dog transmission in the UK occurred is something that vets are still looking in to, but as yet, there has been no evidence of a situation occurring that might have enabled this following a known path, such as the blood transfusion or bite methods as mentioned above.

It is also worth bearing in mind that leishmaniosis is a zoonotic condition that can also be passed on from dogs to people, although this is very rare, and the condition can usually be treated with prompt intervention.

The symptoms of leishmaniosis in dogs

Whilst it is of course concerning to learn that a disease that is currently very rare in the UK can be caught from other dogs who might have been exposed to sand flies and/or travelled outside of the UK, leishmaniosis is still not common and so should not be considered to be widespread cause for alarm.

However, this knowledge does open up the potential range of ways in which any given dog might be exposed to leishmaniosis in the first place, and so it is a good idea for dog owners in the UK to familiarise themselves with the symptoms of the condition.

These may include:

• Skin problems and changes to the appearance and texture of the dog’s skin.
• Unexplained weight loss and loss of condition.
• Lethargy, exercise intolerance and a loss of interest in playing and walks.
• Excessive thirst and correlating need to urinate.
• Sickness and diarrhoea.
• Nose bleeds and/or sore, inflamed eyes.
• Lameness or discomfort when walking.

All of these symptoms can also be caused by various other health conditions too, and so it is important to contact your vet immediately if you spot such symptoms or have any concerns, so that your vet can reach a formal diagnosis and determine the best course of treatment.

Always be sure to tell your vet if your dog has travelled outside of the UK (even if this was not recently) or if they have been in contact with any other dogs that have.