A fisiologia do ciclo estral da fêmea canina: Revisão bibliográfica

Abstract

Female dogs are monoestrous domestic non-seasonal species that do not depend on the season to ovulate and, therefore, their ovulation is spontaneous. The estrous cycle of female dogs is not something concrete, as each female dog has its own cycle and specific behavior in each reproductive phase. Puberty varies between six and 10 months in small dogs and eight to 24 months in large dogs. The reproductive cycle of female dogs is divided into four distinct stages: i) proestrus (lasting five to 20 days); ii) estrus (lasting four to 12 days); iii) diestrus (lasting 60 days); and iv) anestrus (lasting 120 to 240 days). Ovulation occurs in the face of a high dose of luteinizing hormone (LH) and follicle stimulating hormone (FSH), and can last from 48 to 60 hours after the peaks of these hormones. Diagnosis of the phases of the estrous cycle is performed through complementary exams such as vaginal cytology, hormone level measurement (progesterone and estrogen), ultrasound and vaginoscopy. The behavior of the dog will depend on which phase of the reproductive cycle she is in, since each phase has a predisposing hormone that causes changes and modifications in her behavior and reproductive anatomy. In view of this, it is important to seek to improve more effective methods for diagnosing the different phases of the estrous cycle. This could include research and development of new diagnostic techniques that are more accurate, faster and accessible to veterinarians.