A dog can be aggressive towards other dogs in the same house or with unfamiliar dogs. This is considered normal. Sometimes though, a dog becomes excessively aggressive towards other dogs. This behavior can be due to learning and/or genetic.
Inter-dog aggression normally happens in non-neutered dogs of same sex from the age of puberty (six to nine months) or when they are socially mature (at 18 to 36 months).
Growling, biting, snapping, lip-lifting and lunging towards other dogs are some of the common symptoms of dog aggression. These behaviors may be accompanied by fearful or submissive body postures, crouching, tucking the tail under, lip-licking and backing away. More discreet signs of social control are noticeable before a severe inter-dog aggression incident in the same household. One tactic a dog may use is staring and blocking the other dog’s entrance into a room. A specific condition sometimes triggers the aggression, even though the dogs normally get along well.