Leishmaniasis in dogs is a parasitic disease that is incurable and can be fatal without treatment. Early diagnosis and the use of medications, however, can positively influence the course and symptoms. Dogs should be protected from infection by preventing contact with the pathogen and the sandflies that transmit it.

From Sandfly to Dog – Transmission of Leishmaniasis

Leishmaniasis is one of the Mediterranean diseases in dogs. The disease is caused by Leishmania infantum, a single-celled parasite that infects and damages body cells. The parasite is endemic in southern Europe countries such as Southern France, Spain, Portugal, Italy, Greece, Turkey, Bulgaria, and Croatia. Therefore, dogs living in these countries or traveling there are at risk of becoming infected with leishmaniasis. Fotunately leishmaniasis is usually not found in the United States.

Canine leishmaniasis is a vector-borne disease, transmitted from sandflies to dogs. When female sandflies of the genus Phlebotomus bite infected animals, they acquire the parasite during their blood meal.

In the sandfly, Leishmania infantum undergoes further development – from the immobile (amastigote) to the mobile (promastigote) form. The promastigote form reaches the salivary glands of the sandflies. When the fly bites another animal, it injects the parasite into the host with its saliva.

In dogs, the parasitic single-celled organisms are engulfed by immune cells, where they multiply and transform into the immobile forms. After being released from the cells, they enter the bloodstream, spread throughout the dog’s body, and can infect other organs.

Leishmaniasis is a zoonosis. Humans can become infected with Leishmania and develop various clinical manifestations affecting the skin, mucous membranes, or internal organs. In addition to dogs, many rodents and foxes also harbor the parasites and are considered reservoirs. Besides transmission through sandflies, direct transmission has also been described.

Symptoms of Leishmaniasis in Dogs

Following an infection with the parasite, the manifestation of subclinical, mild, or severe clinical signs depends on the dog’s immune response. Additionally, the incubation period (time until the onset of leishmaniasis symptoms) can range from months to years.

The disease typically takes a systemic course in almost all dogs. Around 90 percent of canine leishmaniasis cases also present with skin alterations.

Common symptoms of canine leishmaniasis include:

The disease progression is divided into four stages, based on the severity of clinical symptoms and the level of detected antibody titers.

While the first two stages are characterized by mild symptoms and laboratory value changes, stages three and four involve severe illnesses with clear signs of kidney failure, which is also the most common cause of death in dogs with leishmaniasis.

The prognosis for dogs with leishmaniasis is cautious. Complete elimination of the pathogen from the body is not possible. However, clinical symptoms can often be improved and controlled with treatment. Relapses are common, and dogs showing signs of kidney failure have a poor prognosis.

Diagnosis and Treatment of Leishmaniasis in Dogs

Dogs originating from or traveling to endemic areas should be tested for Mediterranean diseases in dogs, specifically leishmaniasis.

For this, a blood test is necessary, usually conducted three months after the stay. Cell or tissue samples from the skin, lymph nodes, or bone marrow can support or confirm the diagnosis.

If leishmaniasis is diagnosed in a dog, regular check-ups should occur to monitor the progression of the disease and detect kidney problems early. For dogs with a positive Leishmania test, it is recommended to have check-ups every three to six months. Possible accompanying diseases also need to be clarified for preventive and treatment decision-making.

Various medications are available for the therapy of canine leishmaniasis. Allopurinol, Miltefosin, or antimonials are commonly used as monotherapy or in combination. Depending on the clinical manifestation of the disease and the medication, treatment may be necessary for weeks, months, or lifelong.

The earlier the treatment of infected dogs occurs, the higher the chance of delaying the onset of the disease or keeping the symptoms in check. The use of medications depends on the stage of the disease. If the dog is suffering from an advanced stage of leishmaniasis with existing kidney function alterations, additional treatment for kidney failure is indicated.

In addition to fluid therapy and additional medications, specific nutrition may be necessary.

Prevention of Leishmaniasis in Dogs

The most important measure for preventing canine leishmaniasis is avoiding exposure. If possible, dogs should not travel to endemic areas and should not have contact with infected dogs. If staying in Mediterranean countries, keeping the dog indoors during the fly activity of sandflies (twilight hours) can be helpful.

Mosquito nets on windows and doors, as well as mosquito nets (mesh size less than one millimeter) over the sleeping area, help repel sandflies. Additionally, spot-on preparations or collars with repellents should be used.

For several years, there has been a vaccine that can be used in Leishmania-negative dogs planning to travel to endemic areas. This vaccine aims to prevent severe clinical manifestations of the disease. However, it does not protect against infection.

Special Nutrition in Case of Infection

Dogs with leishmaniasis should receive a diet containing high-quality proteins that optimally supply the dog with nutrients. Like healthy dogs, the nutritional and energy needs should be determined, and the diet adjusted accordingly.

If symptoms of kidney problems or changes in kidney values are present, the dog may need a special diet for kidney disease. If dogs are receiving Allopurinol as part of leishmaniasis therapy, the diet should also have a low purine content.

A side effect of Allopurinol is the inhibition of Xanthine Oxidase. This enzyme is involved in the conversion of purines to uric acid via hypoxanthine and xanthine. When inhibited by Allopurinol, an increased formation of xanthine crystals occurs, which can deposit in the urinary tract and lead to kidney stones.

Beware of Leishmaniasis in Humans!

If your dog is infected with leishmaniasis, extreme caution is required as the disease can be transmitted from dogs to humans — and is often life-threatening for humans. There is a risk of infection if, for example, you are attacked by an infected dog or if the pathogens are transmitted through an open wound of the animal.

The Three Forms of Leishmaniasis

Leishmaniasis is classified into three forms — cutaneous leishmaniasis, visceral leishmaniasis, and mucocutaneous leishmaniasis.

Cutaneous leishmaniasis is the most common form, affecting the skin of humans. In visceral leishmaniasis, both the skin and internal organs are involved. It often occurs as a co-infection with an HIV infection.

The third type — mucocutaneous leishmaniasis — affects the mouth and mucous membranes, with the nasal-pharyngeal region being particularly affected.

When to Consult a Doctor

If you suspect an infection, it is crucial to consult a specialist in dermatology, infectiology, or tropical medicine. This should be done if you, for example, experience high, irregular fever, or have had it, or if you notice anemia, weight loss, or spleen pain. The doctor can diagnose a possible disease using skin or mucous membrane samples and discuss specific therapeutic measures with you.