Mucosal Leishmaniasis: An Atypical Form of Canine Leishmaniasis (Prospective Screening Carried Out Over 983 Dogs)
*Pablo Gomez Ochoa, Manuel Gascon Perez, Maria Teresa Verde Arribas, Carmen Aceña Fabian, Juan Antonio Castillo Hernandez, Cristina Rodriguez Serrano
Canine leishmaniasis is an endemic zoonotic disease highly widespread in the Mediterranean basin. There is a broad spectrum on clinical features ranging from local cutaneous forms to visceral forms, depending mainly on host's immune response. Mucosal leishmaniasis is an atypical presentation form produced by metastatic leishmanial dissemination all through the mucous membranes that was firstly described by Font et al. in 1995. To try to describe five new cases of mucosal leishmaniasis is the first objective of this work, one of the cases was localized on a bitch nipple, and that, to the authors' knowledge hasn't been previously described. Second objective is focused in the study of the incidence of this rare leishmaniasis type, in order to make a right valuation within the differential diagnosis of tumor-like lesions of mucous membranes.
The present study was accomplished over 983 dogs that were brought to "Facultad de Veterinaria de Zaragoza" during the 2000-2001 years period. All of them underwent serological leishmania analysis by means of DAT. Since 76 of the dogs were confirmed as leishmania positive, their mucous membranes were carefully watched afterwards. On five, out of the 76 dogs, proliferative lesions were found. Therefore a thorough history record was made on each of these dogs. So, tissue impressions, and/or needle aspirations (according to locations), and N-N-N medium isolation from the lesion, lymph node and bone marrow, and leishmanin skin test, were performed.
According to obtained results, mucosal leishmaniasis prevalence was established about 0.50% and incidence, only considering the number of risky animals to manifest this kind of disease only those sick, was 6.57%. Injuries were found in: gums, tongue, penis, nose and nipple. Just one of the dogs, showed another symptomatology and other three dogs from the five studied, had been previously treated. On tissue impressions and needle aspirations smears, inflammatory cells were discovered (macrophages with vacuolated cytoplasm, lymphocytes, neutrophils, plasma cells) over all five dogs. Amastigotes presence came up on four dogs, being the parasite isolated on all the animals. Leishmanin skin test became positive for all the dogs, with a mean value of 11 mm.
Mucosal leishmaniasis is caused by bloodstream dissemination of infected macrophages from spleen, bone marrow...to other tissue. Explanation, nowadays, seems to be clear: little trauma stimulate macrophagic migration. Considering the relatively high incidence, obtained in this assay, proliferative lesion appearing, might be taken into account in dogs with active leishmaniasis, as in animals previously treated. Moreover, although not too frequent, mucosal leishmaniasis must be included in the differential diagnosis of mucous membranes tumor-like lesions with mycobacterial granulomas, generalized mycosis, transmissible venereal tumors, eosinophilic granulomas and other neoplastic processes.