Unveiling prognostic indicators in canine leishmaniosis: two decades of evidence

Canine leishmaniosis (CanL), caused by Leishmania infantum, can be subclinical or present as a systemic, chronic, and potentially fatal disease. Treatment response in sick dogs is influenced by many factors associated with the host, the vector, and the environment. This study aimed to identify risk factors for poor prognosis in CanL, focusing on demographic, epidemiological, and clinical/clinocopathological variables.

A retrospective analysis was conducted on a cohort of 300 dogs with CanL diagnosed between 2000 and 2022. Two logistic regression models were built to identify variables associated with an increased risk of relapses requiring repeated leishmanicidal treatments or of mortality due to CanL. A database with several variables was used to perform the study. These included demographic (age, sex, breed, and body weight), epidemiological (living conditions, travel history, and preventative measures), and clinical variables (clinical signs reported by the pet owner and physical examination findings, antibody titers, and LeishVet clinical stage), treatment history (first-line treatment, drug combinations), and outcome, among others. All analyses were conducted using R software and applying a significance level of 5% (P < 0.05).

Young dogs and those displaying weakness and ocular signs were more likely to develop relapses and require multiple leishmanicidal treatments, while weight loss was associated with a decreased risk. Additionally, dogs treated with miltefosine in combination with allopurinol as first-line treatment had a fivefold higher risk of needing multiple leishmanicidal treatments than those receiving meglumine antimoniate and allopurinol. Medium- to large-sized dogs had a fourfold higher mortality risk than small dogs, while this risk was almost 25 times higher in dogs in LeishVet stage IV compared with those in stage I. Mortality risk was also significantly higher in dogs displaying weakness, gastrointestinal signs, and lymphadenomegaly. Conversely, treatment with domperidone was associated with an 88% reduction in mortality risk.

Our study highlights important risk factors for poor prognosis in CanL that should be carefully considered by clinicians and researchers when managing sick dogs, particularly regarding therapy decision-making.