Leishmaniasis in Dogs

What is leishmaniasis?

The causative agent of canine leishmaniasis is the single-celled protozoan Leishmania infantum. It undergoes a host change between sand flies and mammals: In the sand fly (genus Phlebotomus), the parasite exists as a flagellated promastigote form; in the mammalian host, it exists as a non-flagellated amastigote form within macrophages. When the sand fly bites, promastigotes enter the skin, are taken up by cells of the mononuclear phagocytic system, and are distributed via the lymphatic and bloodstream primarily to the spleen, liver, bone marrow, and lymph nodes.

Transmission by sand flies

Leishmania, the causative agents of leishmaniasis, are small, obligately intracellular protozoan parasites transmitted by sandflies. The sandflies ingest the parasites when they bite an infected host. The Leishmania parasites continue to develop within the sand flies’ bodies (biological transmission) and are transmitted to a new host when the fly bites.

The incubation period for leishmaniasis ranges from a few weeks to many years. Leishmaniasis is not endemic in Germany, despite the importation of infected animals. The disease is typically found in the Mediterranean region, Asia, South America, and parts of Africa.

The main area of distribution is the Mediterranean region; other endemic areas are located in Asia, the Middle East, Central and South America, and Africa. In Germany, the disease is not considered endemic and occurs primarily in imported animals or following stays abroad. Dogs are the most important reservoir for human infection, which gives the disease zoonotic significance.

Symptoms of Leishmaniasis in Dogs

The wide variety of possible symptoms makes it very difficult to diagnose leishmaniasis. Early signs include fraying of the ears (as if the edges had been nibbled by flies). This often leads to small cracks, usually accompanied by scaling on the ears, head, and eventually the entire body. The condition is accompanied by small, open ulcers (skin sores). These sores are usually round and heal extremely poorly. Starting with hair loss, these ulcers gradually spread to the head, hind legs, and eventually the entire body. Affected animals suffer from loss of appetite, excessive claw growth, nosebleeds, and chronic diarrhea, and they lose weight. This is followed by anemia, lameness, and ultimately kidney failure, which is the most common cause of death in affected dogs.

The clinical picture is exceptionally diverse, ranging from subclinical infection to severe multisystemic disease. Characteristic features include skin lesions with scaling, hair loss, and poorly healing ulcers—often on the edges of the ears and the head—as well as excessive claw growth (onychogryphosis), swollen lymph nodes, weight loss, and nosebleeds. The course of the disease depends heavily on the individual’s immune response; progressive kidney damage is the most common cause of death.

Rapid Tests for Leishmaniasis

The clinical signs are nonspecific, which is why diagnosis plays a central role. In dogs with a compatible clinical picture, the detection of specific antibodies against Leishmania is the most common method; a positive serological status correlates well with the disease in affected animals.

The Fassisi® LeishMa detects antibodies against Leishmania in serum, plasma, or whole blood. Antibodies against Leishmania are also detected in the combination tests EhrLeish (together with Ehrlichia canis), CanVecto 4, and CanVecto Trio, which facilitates the simultaneous screening of multiple pathogens from a single sample in cases of vector-borne diseases and when there is a relevant travel history.

References can be found here.