Is signalment associated with clinicopathological findings in dogs with leishmaniosis?

Relapses in canine leishmaniosis: risk factors identified through mixed-effects logistic regression

BACKGROUND

Canine leishmaniosis (CanL), caused by Leishmania infantum, is an important vector-borne parasitic disease in dogs with implications for human health. Despite advancements, managing CanL remains challenging due to its complexity, especially in chronic, relapsing cases. Mathematical modeling has emerged as a powerful tool in various medical fields, but its application in understanding CanL relapses remains unexplored.

METHODS

This retrospective study aimed to investigate risk factors associated with disease relapse in a cohort of dogs naturally infected with L. infantum. Data from 291 repeated measures of 54 dogs meeting the inclusion criteria were included. Two logistic mixed-effects models were created to identify clinicopathological variables associated with an increased risk of clinical relapses requiring a leishmanicidal treatment in CanL. A backward elimination approach was employed, starting with a full model comprising all potential predictors. Variables were iteratively eliminated on the basis of their impact on the model, considering both statistical significance and model complexity. All analyses were conducted using R software, primarily employing the lme4 package, and applying a significance level of 5% (P < 0.05).

RESULTS

This study identified clinicopathological variables associated with an increased risk of relapses requiring a leishmanicidal treatment. Model 1 revealed that for each 0.1 increase in the albumin/globulin ratio (A/G) ratio, the odds of requiring treatment decreased by 45%. Conversely, for each unit increase in the total clinical score (CS), the odds of requiring treatment increase by 22-30%. Indirect immunofluorescence antibody test (IFAT) was not a significant risk factor in model 1. Model 2, incorporating individual albumin and globulins values, showed that dogs with high IFAT titers, hyper beta-globulinemia, hypoalbuminemia, anemia, and high CS were at increased risk of relapse. Both models demonstrated a good fit and explained a substantial amount of variability in treatment decisions.

CONCLUSIONS

Dogs exhibiting higher CS, dysproteinemia, anemia, and high IFAT titers are at increased risk of requiring leishmanicidal treatment upon clinical relapse in CanL. Regular monitoring and assessment of risk factors prove essential for early detection of relapses and effective intervention in CanL cases. The contrasting findings between the two models highlight the complexity of aspects influencing treatment decisions in this disease and the importance of tailored management strategies to improve outcomes for affected dogs.

Distribution of and Relationships between Epidemiological and Clinicopathological Parameters in Canine Leishmaniosis: A Retrospective Study of 15 Years (2009-2023)

Leishmaniosis is a vector-borne disease caused by protozoan parasites of the genus Leishmania, which are zoonotic and have an important impact on animal and public health globally. Between 2009 and 2023, blood samples from domestic dogs with clinical suspicion of leishmaniosis were received from 286 veterinary medical centres throughout mainland Portugal. An enzyme-linked immunosorbent assay (ELISA) was utilised to detect antibodies against Leishmania infantum antigens. Additionally, a complete blood count and tests for total proteins, urea, creatinine and alanine aminotransferase, as well as protein electrophoresis, were also performed. No significant relationship between sex and breed was observed. The age distribution was bimodal, with the highest prevalence of disease occurring at 2-5 years of age and a secondary peak occurring at 6 years or over (p < 0.001). No statistical correlation was observed between creatinine and urea across the ELISA serological groups. In contrast, both the gamma globulin levels (r = 0.45; p < 0.001) and the albumin/globulin ratio (r = -0.36; p < 0.001) exhibited moderate correlations with the ELISA. These findings support recent seroprevalence studies in dogs, with some geographical areas in Northern Portugal exhibiting the highest values, which may be the result of geographical shifts in parasite circulation due to climate change.

Canine Cytokines Profile in an Endemic Region of L. infantum: Related Factors

Canine leishmaniosis is caused by infection with parasite Leishmania infantum, which are transmitted by sandflies Phlebotomus. Canine leishmaniosis is an endemic disease in the Mediterranean region. The immune response could vary between hosts and determines the severity of the disease and clinical features. The aim of this study was to analyze the serum levels of cytokines TNF-α, IFN-γ, IL-2, IL-6, and IL-8, which are related to the activation of Th1 or Th2 immune responses in dogs living in the L. infantum endemic region. Moreover, we intend to relate and correlate these levels with different factors, such as sex, age, diet, lifestyle, and breed. Epidemiological data and serum were recovered for seventy-eight dogs, and serum levels of cytokines described previously were analyzed by using the ELISA method. The results showed differences in serum levels of IFN-γ, IL-2, and IL-8 between breeds. The lifestyle also affected serum levels of IL-2. The main conclusion of this study is that Ibizan hounds and crossbred dogs have a serological profile of cytokines that seems to indicate certain protections against infection by L. infantum compared to boxer and purebred breeds.

Retrospective study of canine peripheral lymphadenopathy in a Mediterranean region: 130 cases

Lymphadenopathy is a common clinical concern in dogs. Causes of lymphadenopathy include neoplasia, infection, and immune-mediated diseases. Seasonal infectious diseases should be considered as a potential cause of lymphadenopathy in endemic regions, such as the Mediterranean region. Therefore, the purpose of this study was to evaluate the causes of peripheral lymph node enlargement in dogs in a Mediterranean region (north‑eastern Spain). In addition, we aimed to assess the relationship between peripheral lymphadenopathy and other clinical data. Medical records of dogs admitted to two referral hospitals in Barcelona (Spain) with peripheral lymphadenopathy and cytological evaluation of lymph nodes, during a 4-year period (2015 to 2019) were included. One hundred and thirty dogs met the inclusion criteria. The most common final clinical diagnoses were lymphoproliferative neoplasia (36%) and dermatological disease (18.4%), followed by vector borne infectious disease (VBID; 16.5%). In the VBID group, 19 dogs were positive for Leishmania infantum and two dogs were positive for heartworm antigen. The presence of lymphadenopathy as the only clinical sign, generalized peripheral lymphadenopathy and internal lymphadenopathy was more frequent in dogs with lymphoma. The patients with metastatic neoplasms had significantly more localized lymphadenopathy compared to the other diagnosis groups. Twenty percent of the dogs had fever and this was more frequent in the immunemediated disease group. Our findings suggest that lymphoma is the most likely cause of lymphadenopathy in dogs. Clinicians should consider lymphoproliferative neoplasia in dogs with general peripheral lymphadenopathy concurrent with internal (abdominal or thoracic) lymphadenopathy and without other clinical signs. A higher incidence of immune-mediated disease was found in the population of febrile dogs included in this study.

Nutritional Modulation of the Immune Response Mediated by Nucleotides in Canine Leishmaniosis

Leishmaniasis is an emerging, uncontrolled, and neglected zoonotic disease. Climate change is contributing to its ongoing global expansion. The dog is the main reservoir; hence the importance of implementing effective treatment, prevention, and control measures in this animal species to protect public health. However, although the standard treatment for canine leishmaniosis (CanL) is effective, it does not provide full parasitological clearance, and side effects and drug resistance have been described. The host's immune system plays a key role in the establishment and evolution of leishmaniasis. Dietary nucleotides modulate the immune response and, given their reported efficacy and safety in sick and clinically healthy Leishmania-infected dogs and because they represent a sustainable option with no associated side effects or resistance, they could be included within the prevention, treatment, and control strategies for leishmaniasis. This article briefly summarizes the scientific literature on CanL management, including unresolved issues, and reviews the scientific evidence on immunomodulatory effects of dietary nucleotides in different animal species. It also proposes a CanL management algorithm, including nucleotides. It is concluded that nutritional modulation of the immune response with nucleotides can contribute to better management of leishmaniasis following a One Health approach, especially in the COVID-19 era.