Scoring clinical signs can help diagnose canine visceral leishmaniasis in a highly endemic area in Brazil

Canine visceral leishmaniasis (CVL) diagnosis is still a challenge in endemic areas with limited diagnostic resources. This study proposes a score with the potential to distinguish positive CVL cases from negative ones. We studied 265 dogs that tested positive for CVL on ELISA and parasitological tests. A score ranging between 0 and 19 was recorded on the basis of clinical signs. Dogs with CVL had an overall higher positivity of the majority of clinical signs than did dogs without CVL or with ehrlichiosis. Clinical signs such as enlarged lymph nodes (83.93%), muzzle/ ear lesions (55.36%), nutritional status (51.79%), bristle condition (57.14%), pale mucosal colour (48.21%), onychogryphosis (58.93%), skin lesion (39.28%), bleeding (12.50%), muzzle depigmentation (41.07%), alopecia (39.29%), blepharitis (21.43%), and keratoconjunctivitis (42.86%) were more frequent in dogs with CVL than in dogs with ehrlichiosis or without CVL. Moreover, the clinical score increased according to the positivity of all diagnostic tests (ELISA, p < 0.001; parasite culture, p = 0.0021; and smear, p = 0.0003). Onychogryphosis (long nails) [odds ratio (OR): 3.529; 95% confidence interval (CI): 1.832-6.796; p < 0.001], muzzle depigmentation (OR: 4.651; 95% CI: 2.218-9.750; p < 0.001), and keratoconjunctivitis (OR: 5.400; 95% CI: 2.549-11.441; p < 0.001) were highly associated with CVL. Interestingly, a score cut-off value ≥ 6 had an area under the curve of 0.717 (p < 0.0001), sensitivity of 60.71%, and specificity of 73.64% for CVL diagnosis. The clinical sign-based score for CVL diagnosis suggested herein can help veterinarians reliably identify dogs with CVL in endemic areas with limited diagnostic resources.