Abstract

Background: Canine leishmaniasis (CanL) is an important problem in veterinary medicine. Since 2011, a vaccine against leishmaniasis is commercially available in Europe. This vaccination allows an approximate four-fold decrease of symptomatic active infection risk. At present, clinical observations on vaccinated dogs are limited, and in controlled experiments it has been reported that a certain number of vaccinated dogs can still be infected. In practice, these cases could be difficult to interpret based on conventional serological diagnostic tools. The current case report describes a complex diagnosis of CanL in a vaccinated dog and emphasizes the role of molecular techniques as a useful diagnostic approach.

Case presentation: An intact female 6-year-old boxer dog weighing 28 kg vaccinated against leishmaniasis was admitted to the Veterinary Clinic with mild alopecia, moderate dermatitis with abundant dandruff and a diffuse and marked lymphadenomegaly. While no relevant alterations were evidenced by hematological and biochemical analyses, the indirect fluorescent antibody test (IFAT) for Leishmania infantum was positive with a titer of 1:1280, and a qPCR analysis targeting L. infantum kinetoplast minicircle DNA suggested the diagnosis of CanL. In light of the qPCR results, the dog was subjected to anti-Leishmania therapy with miltefosine for 28 days and allopurinol for 6 months. The dog was monitored 4 times after initial diagnosis until day 294, and a progressive overall improvement and complete clinical remission was observed.

Conclusions: This case report evidences a further complexity in CanL diagnosis in vaccinated dogs, underlining the utility of a molecular approach in these particular complex cases, as previously verified in borderline cases or during disease relapse.

Keywords: Canine leishmaniasis, leishmania infantum, qPCR, vaccine