BackgroudExtramedullary hematopoiesis (EMH) is defined as the presence of hematopoietic stem cells such as erythroid and myeloid lineage plus megakaryocytes in extramedullary sites like liver, spleen and lymph nodes and is usually associated with either bone marrow or hematological disorders. Mammary EMH is a rare condition either in human and veterinary medicine and can be associated with benign mixed mammary tumors, similarly to that described in this case.Case presentationHematopoietic stem cells were found in a benign mixed mammary tumor of a 7-year-old female mongrel dog that presents a nodule in the left inguinal mammary gland. The patient did not have any hematological abnormalities. Cytological evaluation demonstrated two distinct cell populations, composed of either epithelial or mesenchymal cells, sometimes associated with a fibrillar acidophilic matrix, apart from megakaryocytes, osteoclasts, metarubricytes, prorubricytes, rubricytes, rubriblasts, promyelocytes, myeloblasts. Histological examination confirmed the presence of an active hematopoietic bone marrow within the bone tissue of a benign mammary mixed tumor.ConclusionsEMH is a rare condition described in veterinary medicine that can be associated with mammary mixed tumors. It's detection can be associated with several neoplastic and non-neoplastic mammary lesions, i.e. osteosarcomas, mixed tumors and bone metaplasia.

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SUMMARYThe effects of gestation and lactation on the dynamics of the thyroid hormones, triiodothyronine (T 3 ) and thyroxine (T 4 ) were evaluated in Crioula Lanada Serrana ewes from the plateau region in Santa Catarina -Brazil. To evaluate the effects of gestation, twenty four ewes were randomly divided into groups I and II. Group I was composed of 12 pregnant ewes and the control group (II) was composed of 12 non-pregnant ewes. The effects of lactation were evaluated in the same ewes of group I after parturition (LE) and in the control group (NL). Blood samples were taken in the first, second and third periods of gestation, at parturition, and at 30, 60 and 90 days of lactation. T 3 and T 4 concentrations were determined by radioimmunoassay (RIA). Pregnant ewes showed lower serum concentrations of T 3 and T 4 than those of non-pregnant ewes. At parturition, there was no significant difference in T 3 concentrations between groups I and II (p>0.05). During lactation, serum T 3 concentrations were lower (p≤0.05) in LE than in NL ewes. Serum T 3 concentrations were greater (p≤0.05) at lambing than during the lactation periods. Serum T 4 concentrations in LE at parturition did not differ (p>0.05) from those of NL ewes. During lactation, T 4 concentrations of LE were lower (p≤0.05) than those of the NL ewes. The results of this study have shown that gestation causes a variation in the T 3 and T 4 serum concentrations, and that lactation results in a decrease of serum concentrations of T 3 and T 4 in Crioula Lanada Serrana ewes. RESUMOOs efeitos da gestação e lactação sobre a dinâmica dos hormônios tireoidianos triiodotironina (T 3 ) e tiroxina (T 4 ) foram avaliados em ovelhas Crioula Lanada Serrana na região do Planalto Serrano Catarinense. Para avaliar os efeitos da gestação, foram utilizadas vinte e quatro ovelhas distribuídas aleatoriamente em dois grupos. O grupo I foi formado por 12 ovelhas gestantes e o grupo controle por 12 ovelhas não gestantes (grupo II). Os efeitos da lactação foram avaliados nas mesmas ovelhas do grupo I após a parição (LE) e no grupo controle (NL). Foram colhidas amostras sanguíneas no primeiro, segundo e terceiro terço da gestação, ao parto e aos 30, 60 e 90 dias de lactação. As concentrações de T 3 e T 4 foram determinadas por radioimunoensaio (RIA). As ovelhas gestantes apresentaram concentrações séricas de T 3 e T 4 inferiores àquelas não gestantes. Ao parto não houve diferença significativa nas concentrações de T 3 entre os grupos I e II (p>0,05). Durante a lactação as concentrações Archivos de zootecnia vol. 59, núm. 228, p. 510

Foi realizado um estudo retrospectivo dos resultados dos exames citológicos provenientes dos arquivos do Serviço de Citopatologia do Laboratório de Patologia Animal, Faculdade de Medicina Veterinária e Zootecnia, Universidade Estadual Paulista, Botucatu, São Paulo, entre janeiro de 1994 e dezembro de 2008. Do total de 139.986 animais atendidos no Hospital Veterinário da instituição, 11.468 (8,2%) foram encaminhados para exame citológico. Desses diagnósticos, 57,28% corresponderam a lesões neoplásicas, 19,28% a lesões inflamatórias e 14,79% a processos não neoplásicos (imunológicos, degenerativos, hiperplásicos ou displásicos). Não foi possível concluir o diagnóstico por meio do exame citológico em 7,28% dos casos e não haviam informações diagnósticas registradas em 1,37% dos casos. Dentre os animais que mais receberam indicação para exame citológico destacaram-se os caninos (92,06%), seguidos pelos felinos (4,08%), bovinos (1,77%) e equinos (1,30%). Lesoes neoplásicas foram as mais comumente observadas e foram mais prevalentes nos cães (59,18%), afetando principalmente animais com idade média de 119,60 meses e principalmente fêmeas (61,61%). O incremento anual observado ao longo dos 15 anos de aplicação da citologia demonstra que o exame citológico é um método de suma importância para confirmar, sugerir ou afastar o diagnóstico de diversas afecções, inclusive neoplasia, em todas as espécies animais.

We read with special interest the article 'Canine hair-follicle keratinocytes enriched with bulge cells have the highly proliferative characteristic of stem cells' by Kobayashi et al. 1 published in Veterinary Dermatology. The study showed encouraging results, suggesting the existence of an epithelial stem cell compartment, based on immunohistochemistry, culture, microdissection and flow cytometry analysis.Currently, there is increasing interest in the follicular stem cell compartment, because this cell type is characterized by extensive growth and differentiation capacity, which may be applied to the development of new strategies in regenerative medicine and gene therapy. 2,3 Although occasionally forgotten, one of the applications of this new field of research resides in the better understanding of adnexal tumour differentiation and further elucidation of the histogenesis of a given tumour. 3 Despite interest in this approach, there are few studies describing the use of immunohistochemical markers to localize stem cell candidates in animal neoplasms. 1,2,4,5 Among these markers, CK15, CD34 and nestin are the only proteins that have been used in stem cell identification in veterinary medicine. 1,2,4,5 Immunolabelling for cytokeratin 15 (CK15) has been reported in sweat gland neoplasms, basal cell carcinomas, trichilemmomas and squamous cell carcinomas. [6][7][8] In contrast, pilomatricomas and Merkel cell carcinoma yielded negative results, [9][10][11] and in a clear cell adnexal carcinoma of a dog only 1% of neoplastic cells, which are supposed to have follicular origin, were positive for CK15. 12 The protein CD34, a hallmark of haematopoietic stem cells, recently demonstrated its value as a follicular stem cell marker in murine bulge keratinocytes. 13 The presence of mRNA and CD34 glycoprotein was demonstrated in the isthmic region of canine hair follicles by in situ hybridization and immunohistochemistry. 7 These findings support the hypothesis that dogs have a bulge-like region, similar to humans and mice. 5 Despite this, no studies regarding CD34 expression in cutaneous neoplasms from animals have been made to date.Finally, the neuroepithelial stem cell protein nestin, which was initially identified as a marker for neuronal progenitor cells, 3 was identified in the middle region of hair follicles in healthy dogs. 2 Nestin expression was variable in sweat gland tumours, 6 squamous cell carcinomas, 8 peritumoural stroma of basal cell carcinomas, trichoblastomas and trichoepitheliomas, 3 but was negative in Merkel cell carcinomas. 8 Expression patterns of other stem cell markers, such as B-lymphocyte-induced maturation protein-1, p63, CK19, CD200 and pleckstrin homology-like domain family A member 1, 3 need to be investigated in veterinary medicine, both in normal skin and in neoplastic skin disorders.