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Treatment of leishmaniasis: everything you need to know

perro jardin

Medicines for canine leishmaniasis have improved a lot in recent years, but treatment is still long and complicated, and there is no guarantee of success. 

The old saying, "prevention is better than cure", was never so true as for canine leishmaniasis. Once this disease is contracted, the treatment is expensive and prolonged, and relapses or flare-ups are common. Also, although veterinary drugs have fortunately advanced a lot and it is now possible to manage this previously fatal disease, the parasite that causes it cannot always be completely eliminated.

It is therefore important to stress that, although treatments have improved substantially, when it comes to leishmaniasis, prevention is the key!

A crafty disease

Leishmaniasis is caused by Leishmania protozoan parasites; hence its name. These parasites can only survive inside the host's cells, where they reproduce. They manage to hide from the host's defences by invading macrophages, precisely the cells of the immune system that should be responsible for destroying them. These macrophage cells travel throughout the body and so spread the disease to many of the organs, making it very difficult to treat.

As well as outsmarting the body's defences, Leishmania causes confusion. Suspecting that something is wrong, the immune system reacts against the invader. However, the response is not always the most appropriate and can actually trigger the most serious effects of leishmaniasis (such as kidney failure).

Through the microscope, we can see dozens of parasites inside a macrophage. At any point, it will "burst," releasing more parasites that go on to infect healthy cells. (Image by Filipe Dantas-Torres, the annotations are ours).

The fact that an infected dog doesn't develop severe symptoms doesn't reduce the seriousness of the case, as it becomes part of the reservoir, where the agent lives, grows and multiplies, which is a key factor in leishmaniasis transmission.

Treatment and prognosis

Once symptoms appear in internal organs (caused by the immune response), the prognosis is poor, and the vet's choice of treatment will depend on the degree of severity. The most widely used drugs currently are meglumine antimoniate combined with allopurinol, but to be effective they have to be administered exactly as prescribed. The treatment can last for months and does not always achieve complete elimination of the parasite. However, it will allow our furry friend to lead a practically normal life and have very low parasite levels.

Before embarking on a treatment, it's important to know the exact prognosis. In the most severe cases of leishmaniasis, euthanasia―the toughest decision that pet owners face―may be the best option.

LeishVet, a group of veterinary experts in canine and feline leishmaniasis from the Mediterranean Basin and North America, has made a useful classification that takes into account the stage of the disease and its manifestations. We show a summary of this interesting information in the following table.

leismaniasis and prognosis

Information adapted from the LeishVet Group Report for Veterinary Clinicians.

Living with leishmaniasis

If your dog suffers from this disease, it is important to know that it cannot be transmitted to you by direct contact. Transmission of leishmaniasis occurs through the insect vector: the sandfly.

You need to keep in mind that, even with the best medical treatment, signs of the disease can reappear. This may happen for two reasons: first because a parasite load, even a tiny amount, can remain in the body; and second because reinfection is common, especially in high-risk areas, unless preventive measures are taken.

Leishmaniasis cannot always be cured, but loving and patient owners can keep it at bay and so help their faithful companion to enjoy a happy life. This means a long-term commitment: keeping to the treatment, attending regular veterinary check-ups, possible diagnostic tests, and diligently taking preventive measures.

How to prevent canine leishmaniasis

The basis of the preventive measures is avoiding being bitten by the vector, through the use of insecticides and repellents. Vaccination also plays an essential role in the control of this disease. It is also important to be aware of the level of risk in the area where you live and to know which months have the highest sandfly activity there.

A simple and accessible preventive measure for all owners is the use of repellent collars which, in addition to protecting our four-legged friend from sandfly bites, will also safeguard them from fleas and ticks.

In any event, if you notice any symptoms of leishmaniasis in your pet, go to the vet as soon as possible. The sooner you act, the better!