RESUMO As neoplasias hormônio-dependentes podem originar-se de mutações genéticas resultantes da proliferação de células normais ou da multiplicação de células já transformadas por outros carcinógenos. Alguns hormônios e drogas anti-hormonais estão sendo utilizados com sucesso no tratamento dessas neoplasias em humanos. Apesar da freqüência elevada das neoplasias hormônio-dependentes nos animais, seu tratamento com hormônios antagonistas e fármacos anti-hormonais, bem como a identificação imunoistoquímica de receptores hormonais nas neoplasias não fazem parte da rotina dos hospitais veterinários. Palavras

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The effect of hypothyroidism on the solid form of the Ehrlich tumor in intact or castrated adult female mice was studied. Hypothyroidism was induced by treatment with propylthiouracil (PTU). Forty mice were divided into four groups: castrated hypothyroid, intact hypothyroid, castrated euthyroid, and intact euthyroid. The mice were inoculated with suspension cells into the left footpad. The tumor growth curve was determined by measuring the inoculated footpad during 12 days. At the end of the experimental period the mice were sacrificed. Hypothyroidism was associated with a reduction in size of the tumor only in the castrated animals. Although the neoplastic growth was lower, mean nuclear diameter, number of nucleolar organizer regions (NORs), and area of mitosis were higher. In conclusion, hypothyroidism resulted in a delayed growth of the tumor, but it did not affect the malignant features of the neoplastic cells. In addition, the isolated effect of castration caused only mild alterations, whereas hypothyroidism associated with castration resulted in a more prominent delay in the growth rate of the Ehrlich tumor.

ResumoOs tumores odontogênicos são alterações incomuns no cão. O ameloblastoma é considerado uma neoplasia odontogênica benigna, agressiva e não indutiva, comumente localizada na região dos dentes incisivos. Seu diagnóstico conclusivo é obtido através do histopatológico. Devido ao caráter expansivo desta neoplasia uma ressecção com margem cirúrgica adequada é necessária para que se tenha um excelente prognóstico. Um canino, macho, Pequinês de oito anos apresentou um aumento de volume na região rostral da mandíbula, aderido e de consistência moderadamente firme. A radiografia mandibular demonstrou a extensão da lise óssea causada pela neoplasia. O estudo histopatológico identificou a alteração como ameloblastoma. Conciliando dados do exame clínico, estudo radiográfico e histopatológico e após o esclarecimento do proprietário a respeito da estética pós-operatória, foi realizada uma mandibulectomia rostral bilateral. A avaliação radiografica e histopatológica das bordas do fragmento não demonstraram indícios tumorais. O paciente se encontra ativo e saudável sem indícios de metástase ou recidiva desde janeiro de 2010, quando foi realizada a mandibulectomia. Palavras-chave: Cão, tumores, mandíbula AbstractOdontogenics tumors are uncommon in the dog. Ameloblastoma is considered a benign, aggressive and non-inductive odontogenic neoplasia commonly located in the incisor teeth. Its conclusive diagnosis is obtained by histopathological examination. Due to the expansive nature of this neoplasia, its resection needs to have an adequate surgical margin so it will have excellent prognostics. A canine, male, Pekingese, 8 years old had an increased volume in the rostral region of the mandible, adhered, consistency moderately firm. Radiography revealed extensive mandibular bone lysis caused by the neoplasia. Biopsy identified the tumor as ameloblastoma. Combining data from the clinical, radiographic and histopatological study and after explain to the owner regarding the postoperative esthetic it was held a bilateral rostral mandibulectomy. The fragment removed was assessed radiographically and histopathologically for evidence of tumor at its edges. The patient is active and healthy without evidence of metastasis or recurrence. The radiographic and histopathologic evaluation of edges of the fragment showed no tumor evidence. The patient is active and healthy without evidence of metastasis or recurrence since January 2010 when mandibulectomy was performed.