The anecdotes below represent the worst case scenarios of owning a Jack Russell Terrier. Same-sex aggression and aggression towards other breeds of dogs is well documented with this terrier.
Smooth coats shed the most, dropping hair continuously year round.
Rough coats maintain the guard and dead coat, requiring manual shedding a few times a year. The broken coat is an intermediary coat, between the two types. They are extremely intelligent, continue to test their limits throughout their life. This ability to train their owners can include displays of aggressive behavior. Untrained, unsupervised dogs rarely meet their life expectancy.