Positive for leishmania… now what?

Diagnosis, treatment and long-term prevention

Canine leishmaniasis is a complex and silent disease, capable of lying dormant for months or years before revealing its true intentions. This elusive behaviour means that speed and accuracy in diagnosis are determining factors for the animal’s prognosis. Early detection can guarantee a long life without major complications. Discovering it late, on the other hand, can mean living with irreversible organ damage that seriously compromises the dog’s health.

Globally, canine leishmaniasis is estimated to be endemic in around 50 countries, mainly affecting the Mediterranean basin and certain regions of South America. In the Mediterranean area, different studies place the seroprevalence of Leishmania infantum infection between 5% and 30% of the canine population, depending on the area and ecological conditions, and even above 20% in some specific areas of Spain and Italy.

Travelling with your dog: a 7–10% risk if you do not use protective measures

Mathematical models simulating dogs from non-endemic countries travelling to the Mediterranean estimated that, without protection, the average probability of a dog becoming infected after a trip to an endemic area is around 7.8–10.7%, depending on the scenario. When vaccine + repellent is combined in 80–100% of travelling dogs, the risk drops by more than 90%.

Source: https://pmc.ncbi.nlm.nih.gov/articles/PMC9507251/

However, the proportion of dogs that develop clinical disease is usually significantly lower than that of infected dogs: in many series, less than 10% of seropositive dogs show clinical signs at any given time, reflecting the enormous importance of subclinical carriers.

Therefore, the veterinarian must become a strategist: diagnosing, treating, closely monitoring and protecting against new attacks by the Leishmania infantum parasite. At Eurovet Veterinary Clinic, for example, we recommend that any dog living in or travelling to risk areas undergo annual preventive check-ups, even when apparently healthy, because the absence of symptoms never guarantees the absence of the parasite.

Diagnosis is not just about finding the parasite: it is about understanding the patient

The diagnosis of leishmaniasis is not based on a single result, but on the integration of all available information. Serology using ELISA or IFI is one of the initial pillars of diagnosis because it measures the amount of specific antibodies against Leishmania. When these values are very high, there is usually an active clinical picture, although not all dogs with a positive serological test are actually ill; some only reveal that they have been in contact with the parasite.

Rapid tests in the clinic: “express” diagnosis in minutes

Nowadays, there are rapid antibody tests (such as SNAP® or POC tests with recombinant antigens) that can tell you in 8–10 minutes, right in the clinic, if a dog has antibodies against Leishmania infantum. In a recent study, a point-of-care immunochromatographic test showed high sensitivity and specificity, comparable to laboratory IFI, which greatly facilitates the screening of apparently healthy dogs in endemic areas or before travelling.

Several studies have shown that in endemic areas, the percentage of seropositive dogs without clinical signs can easily exceed 70–80% of those infected, which means that serology must always be interpreted in combination with clinical, laboratory and epidemiological data.

When additional accuracy is needed, PCR comes into play. This molecular biology technique directly detects the parasite’s DNA in samples such as blood, bone marrow or lymph nodes, and is particularly valuable in subclinical stages or in situations where the disease is suspected but serology remains low. In daily clinical practice, this test provides great peace of mind for owners who want a quick answer to their uncertainty.

Finally, cytology or biopsy provide irrefutable proof when they allow the parasite to be observed inside macrophages: here there is no room for doubt, the enemy becomes visible under the microscope. To make the process easier for the owner, it is essential to explain that these tests are not a complication, but a way to save time and prevent organ damage.

This entire diagnostic process is carried out under the recommendations of LeishVet, the international group of specialists in leishmaniasis that has established reference guidelines for clinical classification and therapeutic decision-making, and which since 2009 has been updating its consensus on diagnosis, clinical staging, treatment and prevention.

A practical tip we give at Eurovet is for owners to bring a brief list of changes observed at home to each check-up: weight loss, apathy, excessive nail growth, skin problems, swollen glands, increased thirst… Any small detail helps to piece together the clinical puzzle and make decisions based on real data from the dog’s daily life.

General tests: an X-ray of the animal’s internal condition

Once the infection has been confirmed, we need to look further. The tests then become a map describing how the disease is affecting the dog’s vital organs. Blood tests often show altered total protein values: globulins are significantly elevated while albumin tends to decrease. This combination reveals polyclonal gammopathy, the result of chronic antigenic stimulation. In simpler terms, this means that the immune system has been on alert for a long time, building defences against the parasite, although this sustained effort wears down other essential functions, especially albumin production.

Surprise co-infections: when Leishmania does not come alone

Several studies have shown that a significant proportion of dogs with clinical leishmaniasis are co-infected with other vector-borne pathogens, such as Ehrlichia canis or Babesia canis. A study conducted in the Mediterranean basin found that dogs with leishmaniasis were more likely to have rickettsial co-infections, which can aggravate anaemia, thrombocytopenia or weight loss and complicate follow-up. This explains why many clinicians request complete vector disease panels in addition to Leishmania.

In various clinical series of dogs with leishmaniasis, more than half of the patients present hyperproteinemia with marked hyperglobulinemia at the time of diagnosis, and hypoalbuminaemia is often correlated with more advanced disease.

Albumin also decreases because the kidney, damaged by inflammation, is no longer able to retain it properly and loses it through urine. In some cases, this phenomenon is compounded by a reduction in hepatic synthesis due to inflammation and liver involvement. For the dog, this translates into loss of muscle mass, weakness, and a tendency to develop oedema.

Urea and creatinine, the best-known markers of kidney function, may be elevated due to immune complex nephropathy. Leishmania causes the immune system to generate antigen-antibody complexes that are deposited in the glomeruli, causing progressive glomerulonephritis. When this happens, the kidney loses its filtering capacity and symptoms of chronic kidney disease appear. Several studies estimate that between 50% and 80% of dogs with leishmaniasis develop some degree of kidney disease during the course of their illness, and that severe proteinuria and end-stage renal disease are one of the main causes of death in chronic cases, more so than the parasite itself.

Here is an essential recommendation for owners: ensure optimal hydration, especially in summer. Providing constant access to fresh water, offering wet food when appropriate, or even resorting to supplements recommended by your vet can help protect the kidneys, which in leishmaniasis act as the “most fragile and most valuable” organ in the body.

Although less common, the liver can also be affected, resulting in slight increases in liver enzymes such as ALT or ALP. Fortunately, liver tissue usually recovers some of its function when the disease stabilises. In any case, owners should avoid administering any medication without first consulting their vet, as some household medicines can seriously damage the liver in these patients.

The blood count, meanwhile, reveals equally significant changes. Anaemia associated with leishmaniasis is usually normocytic, normochromic and non-regenerative, indicating that the bone marrow does not respond with sufficient erythroid production. In some studies of dogs with visceral leishmaniasis, anaemia is present in approximately half of clinical cases, while it is detected in a much smaller percentage of control or seronegative dogs.  Thrombocytopenia may occur as a result of platelet consumption or immune-mediated destruction, and it is not uncommon to find leukocyte abnormalities, ranging from increases due to inflammation to decreases when the bone marrow is depleted. This explains why owners sometimes observe nosebleeds, small red spots on the skin or unexplained tiredness: all of which should be reported to the vet immediately.

Finally, urine is the most honest indicator of kidney health. The presence of protein in the urine, measured by the urinary protein/creatinine ratio (UPC), marks the onset of kidney damage and helps to classify its severity. We now know that most dogs with leishmaniasis have mixed glomerular and tubular proteinuria, and that changes in UPC can predict kidney deterioration even before creatinine levels skyrocket. To facilitate urine sample collection at home, we usually teach owners a few tricks depending on the sex and temperament of the dog, and in some cases we offer assisted collection at the clinic to ensure reliable results that can guide the progression of the disease.

Treatment: what LeishVet says (and what we do in reality)

The standard treatment in Europe is based on the LeishVet Group guidelines, which recommend the combined use of a leishmanicidal drug (to reduce the parasite load quickly) and a leishmaniostatic drug (to prevent the parasite from multiplying again).

There are two main treatment strategies, both equally valid depending on the patient’s clinical situation:

1️⃣ The most classic protocol combines meglumine antimoniate (Glucantime®) administered subcutaneously daily for four to six weeks, together with oral allopurinol for at least six to twelve months. Clinical studies using this protocol indicate that a high percentage of dogs show clear clinical improvement in the first 4–12 weeks of treatment, and that in many cases, the average survival rate can exceed 4 years after diagnosis when proper follow-up is performed and renal complications are controlled.

How do owners really feel about giving their dog daily injections?

A recent qualitative study interviewed owners who administered daily injections of meglumine antimoniate at home. Many described the experience as stressful and emotionally draining, fearing they would hurt their dog or associating injection time with anxiety for both themselves and their pet. Even so, most said they would choose the treatment again given the clinical improvement, although many confessed that if there were an equally effective oral alternative or one with fewer injections, they would prefer it without hesitation. This type of data helps veterinarians understand that therapeutic success depends not only on the drug, but also on how “sustainable” the protocol is for the family.

2️⃣ The alternative, which is particularly interesting when injections are difficult to administer, consists of miltefosine (Milteforan®) administered orally for twenty-eight days, also accompanied by allopurinol for a prolonged period. In specific studies, this combination has been shown to significantly reduce the parasite load and improve clinical manifestations in a large number of patients, with response rates rivalling the classic protocol when cases are properly selected and analyses are monitored.

In recent years, studies have been published evaluating “two-phase” protocols, beginning with allopurinol monotherapy for about three months and adding antimony compounds or miltefosine only in cases where clinical remission is incomplete or relapse occurs. In a cohort of dogs treated in a non-endemic country, the estimated six-year survival rate in cases managed with allopurinol (followed by leishmanicidal therapy when necessary) was around 75–80%, illustrating the potential of structured, long-term medical management.

Nutrition: it does not cure leishmania, but it can change the game

Reviews on parasitic diseases in small animals highlight that a well-formulated diet, rich in high-quality protein, omega-3 and micronutrients such as vitamins A, D, E, B12, zinc and selenium, helps to improve the immune response, reduce inflammation and promote recovery, although it is not a substitute for drug treatment. This is particularly relevant in dogs with kidney disease or weight loss linked to the disease.

At Eurovet, we explain to owners that their dog may improve significantly in a matter of weeks, but this does not mean that the parasite has been eliminated. In fact, we recommend establishing a written treatment schedule for the home, noting times, observed changes and check-up dates, because regularity in treatment is one of the keys to success. We sometimes even suggest using mobile phone alarms or weekly pill boxes so that owners can administer the medication without forgetting or accidentally doubling up.

Allopurinol, the cornerstone of maintenance, is administered for at least eight months, ensuring complete coverage of the vector’s peak season—the Mediterranean summer. During this period, it is essential to monitor for signs of xanthine urolithiasis: changes in urination frequency, straining when urinating, or the presence of blood should prompt an immediate check-up. Long-term follow-up studies have reported isolated cases in which the formation of xanthine stones has even necessitated nephrectomies, underscoring the importance of regular urine checks.

Even so, the overall message is hopeful: several studies conclude that, with protocols based on antimonials or miltefosine combined with allopurinol and proper follow-up, many dogs enjoy average survival rates of more than 4–6 years after diagnosis, and some reach figures similar to those expected in dogs of the same age without leishmaniasis.

Eurovet, pioneers in alternative therapies 🌿🐶

At Eurovet Veterinary Clinic, we have been integrating well-founded alternative therapies into the treatment of leishmaniasis for years. In fact, we began using Artemisia annua long before scientific studies confirmed its effectiveness against leishmaniasis. Today, research supports what we have been seeing in our patients for years: less inflammation, better overall health and a more balanced recovery when combined with official treatment. Our integrative approach is based on science, rigorous analytical control and innovative natural solutions so that dogs live longer and with a better quality of life.✨🩺 

Monitoring and prevention: living with the enemy under control

Overcoming the initial episode of leishmaniasis does not mark the end of the road, but rather the beginning of a new relationship with the disease. The dog will always be more susceptible to developing symptoms again if their immune system becomes unbalanced or if they are re-exposed to the infected sand fly.

For this reason, very specific periodic check-ups are established after treatment. The first check-ups are usually carried out between one and three months after the start of treatment to assess clinical progress, monitor kidney function and detect early signs of improvement or complications. A further check-up after six months allows us to establish whether the animal remains stable and whether the parasite load is decreasing. From then on, annual check-ups (or every six to twelve months in more delicate cases) serve to adjust medication, prevent kidney complications and reinforce protection against the vector. At Eurovet, we always suggest that owners keep a clinical progress notebook, where they can store reports, analytical charts and notes on changes observed at home.

A survey of 155 veterinarians in Portugal analysed how they manage long-term follow-up of leishmaniasis. Clinicians estimated that approximately 43% of dogs they monitor annually experience some form of relapse during their lifetime, and that owners’ financial constraints are one of the factors that most adversely affect the frequency of check-ups and early detection of relapses. In other words, it is often not medicine that is lacking, but the ability to apply it continuously. In follow-up studies of dogs treated with standard protocols, it has been found that relapses rarely occur “suddenly”: weeks or months before, antibody titres begin to rise again, proteinuria reappears, or parameters such as globulins and creatinine worsen. In a classic follow-up study, all dogs that relapsed showed increased IFI titres and parasite load in the lymph nodes before or at the same time as clinical signs appeared. The moral of the story: repeating periodic tests is not a whim, it is the way to see problems coming.

Long-term prognosis: more than half of dogs do better than expected

A recent study that followed dogs with leishmaniasis between 2000 and 2022 analysed which prognostic factors were associated with a good outcome. More than half of the patients (51.3%) had a “good outcome,” defined as needing less than one cycle of leishmanicidal treatment per year and remaining stable, while 22% required frequent treatments and 26.7% died or were euthanised due to the disease. Renal parameters, the magnitude of proteinemia, and the initial clinical stage were key in predicting these outcomes, once again underscoring the importance of early diagnosis and careful analytical monitoring.

Protection against sand flies is an absolute cornerstone of prevention. Positive dogs—and those living in endemic areas—should wear repellent collars or use pipettes throughout the risk season. In addition, it is important not to let dogs sleep outside at dusk or dawn, and even to consider using impregnated mosquito nets in environments with high sand fly density. A useful tip is to schedule the renewal of the repellent collar or pipette application on the first day of each month, so that the owner never overlooks it. Recent consensus in veterinary dermatology emphasises that intensive vector control is one of the most effective strategies not only to protect dogs, but also to reduce the zoonotic risk to the people who live with them.

Vaccination is also part of the overall strategy, although it has specific indications: it is mainly recommended for healthy, seronegative dogs, as its aim is not to prevent infection, but to reduce the risk of clinical disease in case of exposure. In animals that have been treated and, over time, show negative or very low serological titres, the veterinarian may assess vaccination on an individual basis depending on the epidemiological situation. In addition, we explain to owners that the vaccine is most effective when combined with a solid vector protection plan and adapted nutrition that promotes a strong immune system.

The key point for owners to understand is that leishmaniasis is controlled, not eliminated. With proper treatment, constant monitoring and vector protection, the vast majority of dogs can enjoy a completely happy, healthy and active life for many years. In some follow-up studies, the rate of dogs alive several years after diagnosis reaches 75–80% when evidence-based protocols are applied and regular clinical monitoring is maintained, confirming that, when managed correctly, leishmaniasis is no longer a death sentence but becomes a manageable chronic condition.

Conclusion

Managing canine leishmaniasis requires a comprehensive view of the patient and a sustained commitment over time. It is not just a matter of “curing the crisis”, but of maintaining immune balance, protecting vital organs and preventing the parasite from regaining ground. Preventive medicine, vector control, regular check-ups and the active involvement of the owner transform a potentially devastating disease into a perfectly manageable challenge.

When science is combined with daily care at home, the vast majority of dogs affected by leishmaniasis can enjoy the rest of their lives with joy, well-being, and plenty of time to keep wagging their tails.

Scientific references and recommended reading 

Solano-Gallego, L., Miró, G., Koutinas, A., Cardoso, L., Pennisi, M. G., Ferrer, L., Bourdeau, P., Oliva, G., Baneth, G. (2009) – Directions for the diagnosis, clinical staging, treatment and prevention of canine leishmaniosis. – Veterinary Parasitology – Classic LeishVet consensus on diagnosis, staging, treatment and prevention of canine leishmaniasis. – https://www.sciencedirect.com/science/article/abs/pii/S0304401709003124

Solano-Gallego, L., Fernández-Bellon, H., Morell, P., Fondevila, D., Alberola, J., Ramis, A. (2011) – LeishVet guidelines for the practical management of canine leishmaniasis. – Journal of Small Animal Practice – LeishVet practical guide for the clinical management of canine leishmaniasis, with staging and recommended treatment protocols. – https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3125381/

LeishVet Group (2018) – Canine and Feline Leishmaniosis: Guidelines. – LeishVet (consensus document) – Summary and updated version of LeishVet recommendations for diagnosis, treatment and prevention in dogs and cats. – https://www.leishvet.org/wp-content/uploads/2018/09/EN-Guidelines.pdf

Tamponi, C. (2020) – Seroprevalence and risk factors associated with canine leishmaniasis. – Thesis / Epidemiological study – Review of seroprevalence and risk factors for canine leishmaniasis in endemic areas of the Mediterranean. – https://d-nb.info/1224230752/34

Gálvez, R., Montoya, A., Cruz, I., Martín, O., Checa, R., Chicharro, C., Marino, V., Miró, G. (2020) – Latest trends in Leishmania infantum infection in dogs in Spain: mapped seroprevalence and sand fly distributions. – Parasites & Vectors – Study mapping canine seroprevalence and sand fly distribution in Spain, showing high-risk areas. – https://repisalud.isciii.es/bitstreams/cec2a00e-45e4-445c-87fc-d7b289bde508/download

Baxarias, M., Altet, L., Brachelente, C., et al. (2023) – Serological survey of Leishmania infantum in dogs. – Veterinary Medicine and Science – Serological study quantifying the prevalence of infection and proportion of clinically ill dogs in canine populations. – https://onlinelibrary.wiley.com/doi/pdf/10.1002/vms3.1172

Poli, A., Abramo, F., Mancianti, F., Nigro, M., Pieri, S. (1991) – Renal involvement in canine leishmaniasis. – Nephron – Classic work demonstrating that renal involvement is a natural sequela of Leishmania infantum infection in dogs. – https://pubmed.ncbi.nlm.nih.gov/2046828/

Martínez-Subiela, S., Strauss-Ayali, D., Cerón, J. J., Baneth, G. (2013) – Acute phase protein and renal markers in dogs with leishmaniosis. – Research in Veterinary Science – Study showing a high prevalence (≈50–80%) of kidney disease and proteinuria in dogs with leishmaniasis. – https://www.sciencedirect.com/science/article/abs/pii/S0034528813002270

Pardo-Marín, L., Ruiz de Gopegui, R., Pastor, J., et al. (2017) – Evaluation of various biomarkers for kidney monitoring during canine leishmaniasis. – BMC Veterinary Research – Study confirming the frequent presence of mixed proteinuria (glomerular and tubular) and the usefulness of renal biomarkers in CanL. – https://link.springer.com/article/10.1186/s12917-017-0956-0

Torres, M., Bardagí, M., Roura, X., Zanna, G., Ravera, I., Ferrer, L. (2011) – Long-term follow-up of dogs diagnosed with leishmaniasis. – The Veterinary Journal – Long-term follow-up study showing lasting clinical improvements and survival rates of several years with appropriate treatment. – https://pubmed.ncbi.nlm.nih.gov/20594876/

De Jong, M. K., Homan, C., Herremans, T., et al. (2023) – Survival time and prognostic factors in canine leishmaniasis in a non-endemic country treated with a two-phase protocol. – Parasites & Vectors – Evaluates a two-phase protocol with allopurinol and leishmanicidal therapy, with estimated 6-year survival rates of around 75–80%. – https://link.springer.com/article/10.1186/s13071-023-05777-2

Kaempfle, M., Große, M., von Samson-Himmelstjerna, G., Schnyder, M., Pantchev, N. (2025) – Treatment of Leishmania infantum infections in dogs. – Microorganisms – Review of efficacy and survival with protocols based on allopurinol and leishmanicidal combinations in canine leishmaniasis. – https://www.mdpi.com/2076-2607/13/5/1018

Oliva, G., Roura, X., Crotti, A., Maroli, M., Castagnaro, M., Gradoni, L., Lubas, G. (2010) – Guidelines for treatment of leishmaniasis in dogs. – Journal of the American Veterinary Medical Association (JAVMA) – Review of therapeutic protocols, dosages and reference combinations for the treatment of canine leishmaniasis. – https://avmajournals.avma.org/view/journals/javma/236/11/javma.236.11.1192.xml

Noli, C., Saridomichelakis, M. N., Fondati, A., et al. (2024) – World Association for Veterinary Dermatology (WAVD) consensus on canine leishmaniasis. – Veterinary Dermatology – International dermatological consensus updating recommendations on cutaneous manifestations and vector control in canine leishmaniasis. – https://onlinelibrary.wiley.com/doi/abs/10.1111/vde.70006