Parasite Infection (Leishmaniasis) in Dogs

Leishmaniasis is common in areas considered endemic, such as the Mediterranean basin, the Middle East, Central Asia, and South and Central America. This parasitic infection can cause serious, potentially life-threatening disease in dogs. After an infection, the parasite is deposited into the skin and infects local macrophages, one of the body’s major immune cells. From there, the macrophages containing the parasite spread throughout the body, allowing infection of numerous organs.

Dogs showing symptoms of leishmaniasis require immediate veterinary care to slow the progression of disease and minimize organ damage. Although leishmaniasis is a lifelong infection, dogs treated promptly can maintain a good quality of life with minimal symptoms.

Leishmaniasis is potentially zoonotic, and dogs are considered a major source of the parasite in endemic areas. Although direct transmission from dogs to humans does not occur, infection of a dog in the household may indicate that humans have been exposed to infected sandflies. Humans who are malnourished or immunosuppressed are most at risk.

The parasite responsible for leishmaniasis is primarily found in the Mediterranean, the Middle East, Central Asia, and South and Central America however, cases are also starting to appear in North America and Europe.

Other symptoms depend on which other organs are infected.

The causative agent of leishmaniasis is Leishmania, a protozoan parasite that is traditionally found in the Mediterranean, the Middle East, Central Asia, and South and Central America. Cases are also starting to appear in North America and Europe.

Dogs typically acquire the infection through the bite of an infected sand fly, which acquires the bacteria through feeding on an infected animal. Transmission from mother to puppies, venereal spread, and transmission through a contaminated blood transfusion can also occur. Immunosuppressed or malnourished dogs are at a higher risk of infection.

The symptoms of leishmaniasis reflect the widespread infection the disease causes. In dogs, leishmaniasis primarily affects the lymphatic system, the skin, and the eyes.

Diagnosis of leishmaniasis can be difficult, as the symptoms it presents are similar to many other conditions. Diagnostic tests include:

• Physical examination
• Bloodwork
• Urinalysis
• Cytology of a lymph node or bone marrow to identify the parasite
• Biopsy of the skin
• Identification of parasitic proteins in samples from the bone marrow or lymph nodes

Dogs remain infected with leishmaniasis for their entire lives, even with treatment. Treatment focuses on reducing symptoms, and preventing spread of disease to other animals. Management includes:

• Chemotherapy medications that stimulate the immune system against the parasite
• Dietary changes to prevent side effects of immunostimulant medications
• Regular application of topical insecticides to prevent sand flies from feeding
• Regular veterinary examinations to monitor for disease relapse or signs of organ damage

Leishmaniasis is a lifelong infection in dogs, even with appropriate treatment and management. In most cases, treatment improves symptoms and allows for a good quality of life. Mildly affected dogs have the best prognosis for resolution of symptoms, while dogs with very severe disease may have organ damage, particularly kidney failure, that is difficult to manage. Many severely affected dogs are euthanized for these reasons.

Leishmaniasis is contagious, and primarily spread through the bite of sand flies. Cats, horses, humans, and other mammals can also become infected. Reducing the risk of leishmaniasis involves topical insecticides, applied based on veterinary recommendations.

Always consult a veterinarian before choosing external parasite control. Many available products are toxic to pets, especially cats.

All dogs in areas where leishmaniasis is common require regular insecticide application as a preventative measure. In some countries, a vaccine against leishmaniasis is available, and reduces the risk of developing symptoms if a dog becomes infected. Avoiding breeding dogs positive for leishmaniasis can also help reduce spread, as the disease can pass from the mother to the puppies.

Leishmaniasis is common in dogs in areas where the parasite is endemic. Dogs are considered a major source of human infections of leishmaniasis.

• Chemotherapy
• Dietary changes
• Topical insecticides
• Regular veterinary examination