W.L. Tafuri

Canine visceral leishmaniasis: a remarkable histopathological picture of one asymptomatic animal reported from Belo Horizonte, Minas Gerais, Brazil

A remarkable histopathological picture of one asymptomatic dog naturally infected with Leishmania infantum (syn. chagasi) has been presented. Intracellular parasites were ease found in macrophages of all exanimated organs, especially in skin. Embedded paraffin tissues of liver, spleen, axillary and popliteal lymph nodes, and skin (ear, muzzle and abdomen) were stained by hematoxylin and eosin and by immunocytochemical reaction (streptoavidin-peroxidase method) to detect parasites. All organs showed an intense parasitism associated to severe pathological changes. All lymph nodes had conspicuous histological architecture alterations. Lymphocytes were replaced by macrophages stuffed with an intense number of amastigotes forms of Leishmania. The lymphoid nodules (without germinal centers) and the mantle zones in the cortex that surround the follicles were markedly attenuated. Livers showed small intralobular granulomas composed by macrophages loaded with amastigotes. Spleens had an intense depression of the white pulp whereas the lymphocytes were replaced by parasitized macrophages. All fragments of different anatomical region of skin (ear, muzzle and abdomen) showed a diffuse chronic inflammation. The cellular exudate was composed by macrophages, plasmocytes and lymphocytes. Macrophages loaded with amastigotes were ease found in all tissue fragments, but more intense in ear and muzzle. Thus, this fact enhances the importance of asymptomatic dogs in the epidemiology of visceral leishmaniasis.

A new methodology for the improvement of diagnostic immunohistochemistry in canine veterinary pathology: automated system using human monoclonal and polyclonal antibodies

The authors describe their experience with an automated immunohistochemical system applied to canine tissue samples. Twenty human cellular markers specific monoclonal and polyclonal antibodies and two different antigen retrieval methods were used in normal and neoplastic breast tissue, as well as skin samples obtained from female dogs of pure and mixed breeds. The antibodies tested were the most frequently used in human and veterinary medicine studies, employed with diagnostic purposes in breast pathology, as well as in cancer research. Most of them may be used to study other normal and abnormal tissues and included cytokeratins, progesterone receptor, c-erbB2, p53, MIB-1, PCNA, EMA, vimentin, desmin, a-actin, S-100, pan-cadherin, and E-cadherin. The results demonstrated that using an automated staining system it is possible to use different human markers in veterinary pathology. The advantages of automated immunohistochemistry are improved quality, reproducibility, speed, and standardisation.

Detection of Leishmania infantum in the smegma of infected dogs

Considering the venereal transmission of visceral leishmaniasis from dogs to bitches, the aim of this study was to verify if the penile surface and smegma from infected dogs can be the source of parasites in bitches. Twelve Leishmania infantum infected dogs had semen and smegma samples collected for submission to PCR identification of the DNA of the parasite. Semen (41.7%) and smegma (50.0%) have similar positive incidence (P>0.05; Fishers exact test), with 58.3% of the dogs positive for semen and/or smegma samples. The proportion of positivity for both semen and smegma was 33.3%, but 8.3% was positive only for semen, and 16.7% only for smegma, revealing a moderate agreement between tests (K=0.5; Kappa index). It was concluded that Leishmania infantum is present in the smegma of contaminated dogs and it can be a source of parasites for the semen and the bitch.

Hepatic granulomas in canine visceral leishmaniasis and clinical status

The histopathological description of intralobular hepatic granulomas in animals with a defined clinical status (asymptomatic, oligosymptomatic and symptomatic animals) was reported. Seventy-one mongrel dogs naturally infected with Leishmania chagasi were obtained from two Brazilian endemic areas: Joao Pessoa, PB and Belo Horizonte, MG. The hepatic parasite load was determined and compared to granuloma formation. Liver fragments from all infected animals showed remarkable leishmaniotic granulomatous inflammatory reaction. Granulomas with variable size were constituted by macrophages (parasitized or not with amastigotes of L. chagasi), some epithelioid cells, small numbers of lymphocytes, plasma cells, and rare neutrophils. Asymptomatic dogs had higher numbers of granulomas than oligosymptomatic and symptomatic animals from both geographical regions. However, the average diametric size of granulomas was very heterogeneous in all groups, independently of the geographic region (P>0.05). Parasite tissue load did not show any difference among liver fragments of all animals, especially when considering the defined clinical status and/or their geographic origin.

Avaliação de diferentes fixadores na preservação das características histológicas de pele de orelha de cães

Os fixadores biologicos desempenham um papel importante na qualidade final da histologia. Na rotina veterinaria, a biopsia de pele e um procedimento comum e a escolha do fixador e primordial para resultado final adequado. Os fixadores mais usados sao a base de formalina, ainda que sejam toxicos, cancerigenos, de baixa penetracao e de fixacao lenta. Mesmo assim, nao existe um fixador ideal que substitua as suas qualidades. O objetivo deste trabalho foi avaliar qualitativamente a preservacao das caracteristicas histologicas de pele de cao utilizando diferentes fixadores de tecidos incluidos em parafina, cortados e corados pela hematoxilina-eosina. Utilizou-se uma caneta Punch de 4 milimetros para coletar amostras de pele de orelha em seis cadaveres de caes. Apos coleta, os tecidos foram fixados em: (1) Bouin, durante seis horas; (2) Carnoy, durante quatro horas; (3) formaldeido tamponado 10% durante 24 horas, todos sob refrigeracao (4oC). Posteriormente, os tecidos foram processados, cortados e corados em hematoxilina e eosina. As lâminas foram avaliadas, as cegas, por quatro patologistas diferentes, que consideraram aspectos qualitativos a seguir: (1) qualidade da coloracao; (2) preservacao das caracteristicas histologicas; e (3) preservacao dos limites citoplasmaticos utilizando a escala de LIKERT de pontuacao para cada lâmina. O fixador com a maior media de pontuacao em todos os itens foi o formol tamponado com 3,76 pontos, seguido pelo Bouin (3,39) e pelo Carnoy (2,52). O formol pode trazer riscos a saude do profissional que rotineiramente o manuseia, portanto se faz necessaria a busca por fixadores com as mesmas qualidades, mas menos nocivos a saude.