Made available in DSpace on 2015-03-26T13:47:00Z (GMT). No. of bitstreams: 1 texto completo.pdf: 161262 bytes, checksum: 556284ca69c59d692ceef51305bf3697 (MD5) Previous issue date: 2006-09-26 / Universidade Federal de Viçosa / The hair cycle has been extensively studied in humans, sheep and laboratory animals, however there is a lack of studies on dogs. Besides varying according to the species, breed, sex and general health conditions, the hair cycle is mainly affected by climatic variations. The objective of the present work was to analyze and increase our understanding of the hair cycle in three dog breeds with different coats, in the city of Viçosa-MG (latitude -20°45'), in different seasons throughout the year. A total of 21 male healthy dogs, distributed in 3 groups according to coat type, were used in the study. The group Boxer (GB) represented the short-hair coat type consisting of six Boxer dogs, the group Labrador (GL) represented the medium-length-hair coat type consisting of eight Labrador dogs, and the group Schnauzer (GS) represented the long-hair coat type consisting of seven Schnauzer dogs. Hair samples were collected monthly from the area of the shouder over a one-year time period. The trichogram evaluation was used to identify the hair cycle phases through the morphological analysis of hair follicles. The environmental temperature and photoperiod duration in Viçosa-MG were obtained and compared with telogen and anagen hair numbers of the animals in study. Boxer and Labrador dogs showed a larger number of telogen hairs than Schnauzer dogs, and it was found that the cyclic activity of hair follicles in Boxer and Labrador dogs are associated mainly with the variation in the environmental temperature and in a lesser degree with the photoperiod variation, however, apparently the same did not happen with Schnauzers. In addition, it was found that Boxers and Labradors had a larger number of telogen hairs during the hottest months of the year, and an increase in anagen hairs during the coldest months. There was no difference for telogen and anagen hair numbers in the hottest and coldest periods of the year for Schnauzers. / O ciclo piloso tem sido mais estudado nos humanos, ovelhas e em animais de laboratório, porém existem poucos estudos nos cães. Além de variar conforme a espécie, raça, sexo e condições gerais de saúde, o ciclo piloso é influenciado principalmente por variações climáticas. O presente trabalho teve como objetivo analisar e melhorar o entendimento do ciclo piloso em três raças caninas com diferentes pelames que habitam na cidade de Viçosa-MG (latitude -20°45 ), nas diferentes estações do ano, durante o período de um ano. Foram utilizados um total de 21 cães sadios, todos machos, distribuídos em 3 grupos conforme o tipo de pelame. O grupo Boxer (GB) representou a pelagem do tipo curta e foi constituído por seis cães da raça Boxer, o grupo Labrador (GL) representou a pelagem do tipo intermediária e foi constituído por oito cães da raça Labrador e o grupo Schnauzer (GS) representou a pelagem do tipo longa e foi constituído por sete cães da raça Schnauzer. Foram coletadas amostras mensais de pêlos da região da articulação escapuloumeral durante o período de 1 ano. Utilizou-se o exame tricográfico como método de identificação das fases do ciclo piloso por meio da análise morfológica dos bulbos pilosos. A temperatura ambiental e a duração do fotoperíodo da cidade de Viçosa-MG foram obtidas e comparadas com os números de pêlos telogênicos e anagênicos dos grupos de animais deste estudo. Observou-se que os cães da raça Boxer e Labrador apresentam um número muito maior de pêlos telogênicos quando comparados com os cães da raça Schnauzer e que a atividade cíclica dos folículos pilosos nos cães das raças Boxer e Labrador está associada principalmente à variação da temperatura ambiental e em menor grau à variação do fotoperíodo, contudo o mesmo aparentemente não ocorreu nos cães da raça Schnauzer. Além disso, observou-se nos cães da raça Boxer e Labrador um maior número de pêlos telogênicos durante os meses mais quentes do ano, e um aumento dos pêlos anagênicos nos meses mais frios e nos Schnauzers não houve diferença nesses números nos períodos mais quentes e mais frios do ano.

Yes / BACKGROUND: Diffuse alopecia areata (DAA) often leads to a complete hair shedding within a few months. OBJECTIVE: To explore features and mechanisms underlying DAA. MATERIALS AND METHODS: Scalp and hair root dermoscopy were conducted on 23 DAA patients throughout the disease process, 20 patchy Alopecia areata patients, 23 acute telogen effluvium (ATE) patients and 10 normal controls. Histopathology was also evaluated. RESULTS: We found almost all hair roots were anagen in early stage DAA in 18 patients (18/23, 78.3%) within the first 4-8 weeks after hair loss onset. Anagen effluvium (~4 weeks) was followed by catagen (~4 weeks) and then telogen/exogen (~8 weeks) effluvium with overlap. Hair root and proximal hair shaft depigmentation was more prominent in later DAA disease stages. Black dots, exclamation mark hairs and inconsistent thickness of hair shafts were found more often in early than later DAA (Ps < 0.01). Early DAA histopathology revealed more prominent inflammation and hair follicle regression than that observed in the later stages. Patchy alopecia areata patients showed mixed anagen, catagen and telogen hair roots while ATE patients showed increased exogen and mildly decreased hair root pigmentation. CONCLUSION: Sequential cyclic staging of shed hairs in DAA indicates the insult may be hair-cycle specific. We suggest that DAA is initially an anagen effluvium disease involving an intense inflammatory insult, later progressing to a brief catagen effluvium, and then to telogen effluvium with premature exogen, in later stages of DAA. / This study was supported by the following grants to Xingqi Zhang: National Natural Science Foundation of China (81573066); Natural Science Foundation of Guangdong Province (2014A030313098).