You may like to believe that you and your pets are one big family, but not all pets will agree. Sometimes dogs just don't get along! Two female dogs can sometimes coexist, but life is often difficult in a two-dog household unless the two dogs are of opposite sexes.
You may consider your dog to be a family member, but he is also a predator. As a predator, he considers other dogs to be competition for “his” resources. Dogs particularly compete for food, reproductive rights and human attention. Aggression problems that arise between two dogs after the younger of the two matures to adulthood usually occur because the younger dog wants to elevate himself in social status over the older dog. However, humans are also often to blame for discord between housemates.
Multiple Dog Households
Pet owners like to treat all of their pets equally, showing equal amounts of love and attention, giving equal numbers of treats, and greeting their pets at the same time as each other. However, this equal treatment can disrupt the functioning of the pack if one dog is dominant over the other. It is absolutely natural to want to punish one dog for growling at or jumping on another. However, these bloodless battles are vital to keeping the peace, with the dominant dog reminding the social climber how rude he is being. When pet owners protect the dog getting growled at or jumped upon, they lower the social status of the dominant dog and elevate the submissive one. This interference in the natural order of social status adjustment can cause serious problems later.
Same-sex aggression occurs in many breeds, especially terriers. Both males and females can be aggressive toward one another; however, neutering will typically have more of an effect on reducing same-sex aggression in males than spaying will have on aggressive females. Females that come into heat will not usually affect the status quo, unless she experiences changes in her temperament during that time. Adding a third dog to a pair of female dogs will create a change in the social structure, sometimes causing aggression where none existed before. All hope is not lost, even when females start to challenge each other for dominance. With proper obedience training and reinforcement, some females do get along with one another. Avoid female pairs unless you are an experienced pet owner. If you already have a pair of female dogs and find it difficult to control them, animal behaviorists can help find a solution to your problem.
Unplanned Pregnancy, Testosterone & Aggression
One disadvantage to the male-female pair is the surprise litter of puppies that may arrive if neither dog has been sterilized. Although some breeds do not get along well in multiple-dog groups of any kind, male-female groups typically get along better than same-sex female groups. Spaying and neutering is vital in male-female groups. Not only does spaying and neutering prevent accidental pregnancy, but neutering also reduces testosterone levels in males. Testosterone itself is not the cause of fighting; rather, testosterone does cause “intact” males to fly off the handle more easily and prevents them from cooling off quickly.