Unveiling prognostic indicators in canine leishmaniosis: two decades of evidence

Background Canine leishmaniosis 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 variables. Methods 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, body weight), epidemiological (living conditions, travel history, preventative measures), and clinical variables (clinical signs reported by the pet owner and physical examination findings, antibody titers, 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). Results Young dogs and those displaying weakening 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 a first-line treatment had a five-fold 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 to stage I. Mortality risk was also significantly higher in dogs displaying weakening, gastrointestinal signs and lymphadenomegaly. Conversely, treatment with domperidone was associated with an 88% reduction in mortality risk. Conclusions 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.