Los fitoestrógenos (FEs) son compuestos químicos provenientes del metabolismo secundario de algunos vegetales, tienen un efecto potencial sobre los parámetros reproductivos de los animales domésticos, al actuar como agonistas o antagonistas de los receptores estrogénicos. El objetivo de esta revisión es conocer los efectos que produce una dieta rica en FEs en la fisiología reproductiva de los animales de abasto. Se realizó una revisión sistemática en dos bases de datos mediante el uso de palabras clave relacionadas con los efectos que produce la ingestión de FEs en la dieta, sobre la reproducción de animales de abasto, únicamente se consideraron los estudios controlados desarrollados in vivo. Se encontraron resultados contradictorios, por un lado, la ingesta de un alto contenido de los compuestos polifenólicos, provenientes de distintos forrajes en la hembra bovina, estuvo relacionado con la disminución de la fertilidad, presencia de abortos y de quistes ováricos; por otro lado, la ingesta de alto contenido de FEs indujo un aumento en la calidad seminal de los machos de las especies: bovinos, ovinos y lepóridos; por lo que, dichos efectos se pueden atribuir a la concentración, al tipo de FEs, sexo, especie e incluso a la raza del animal.

The issue of stray cats and dogs is a global concern with considerable implications for animal welfare and public health. This review aims to provide an updated and comprehensive analysis of non-surgical contraceptive methods tested in studies controlled in vivo in feline and canine females. Immunocontraception via vaccination against gonadotropin-releasing hormone (GnRH), the luteinizing hormone receptor, zona pellucida proteins, and sperm, or use of viral-vectored delivery, is yet developing. Hormonal treatment (progestins, androgens, or GnRH) analogs act directly to block the reproductive axis. However, it produced essential side effects. Analogs of kisspeptin, non-steroid anti-inflammatory drugs such as firocoxib, and delivery of cytotoxins to the pituitary have shown non-conclusive results. Additional methods have also been tested, such as intraovarian injection of necrosing compounds or intravaginal and intrauterine devices. At present, neither of these methods offers permanent sterility that can replace surgical sterilization techniques. To our knowledge, none are currently authorized by the Food and Drug Administration (FDA) or the European Medicines Agency (EMA) for contraceptive methods or sterilization of cats or dogs. Therefore, it is necessary to continue the development of a compound that warrants the sterility of cats and dogs.

The use of biotechnologies in wild canids, such as in vitro oocyte maturation (IVM) and fertilization (IVF), has received little attention. One of the main reasons is the difficulty in finding a relevant in vitro model, and domestic dogs (Canis lupus familiaris) may be a viable alternative. In vitro oocyte maturation in dogs is not well established, but canine oocytes can spontaneously restart meiosis through adaptations of bovine IVM protocols resulting in maturation rates of 10%–39%. To continue with the development of IVM and IVF protocols, the use of analytical techniques is necessary, but they require a minimum amount of protein. Oocyte protein content has been previously reported in different species. Unfortunately, the protein content in the canine oocyte remains unknown. In the present study, two different Bradford‐based assays were used to determine the protein content in the immature oocyte of the domestic canines. To determine the protein content, 1500 immature oocytes were recovered from the ovaries of bitches and analyzed with Pierce 660 nm Protein Assay and Quant‐iT Protein Assay Kit. Oocyte protein content average with Pierce 660 nm assay was 0.222 µg/oocyte, while for the Quant‐iT Protein Assay Kit, the average was 0.205 µg/oocyte. Knowledge of the amount of protein contained in the canine immature oocyte will favour the design and development of experimental work with greater certainty and efficiency, as well as making efficient use of the samples, which will favour progress in the knowledge of the IVM of canine oocytes.