Why are male dogs aggressive to female dogs?

Male dogs are aggressive to female dogs because they compete for food or territory. Dogs are very territorial animals, so male dogs are aggressive to female dogs. If a male dog is aggressive to a female dog, it may also be because the male dog hates the female dog and feels uncomfortable with the smell of the female dog, so he becomes aggressive to the female dog. However, sometimes a male dog is aggressive and a female dog is just playing and not really fighting with the female dog.