This period is a little more difficult to pinpoint due to the different rate of speed with which dogs mature. But, somewhere between that forth and seventh month of the dog is going to enter into what is commonly called "fear of new situations" periods. One day your pup will be working like a dream and be a well-adjusted dog, and suddenly the next day his training seems to have gone to pot, and he becomes fearful of almost everything that is new to his environment. This is a very difficult period for the dog.
While the common belief is still prevalent that you should not begin training a dog until it reaches six months of age, this is the worse possible time to introduce a dog to a training class.
He is going through a fear period, and nothing could be more of a "new situation" than a training class to a dog who has never been exposed to a large number of dogs and a large number of people, plus noise and confusion.
Dog shows and trials are set up to admit pups only when they reach six months of age. Again, this is the worst time to take a dog for the first venture into the strange world of dog shows. If you plan to show, then make sure your pup is exposed to matches and training classes prior to this period, so that it is not a new situation to him when he reaches the "proper age".
This period can last well into maturity, and if an event occurs that frightens the pup badly, it may permanently stay with him. So be cautious in handling him during this time. Don't insist that he make friends with your long, lost "Uncle Harry" if he appears afraid.
Take him with you when you visit new places, but if he appears fearful, let him stay in the car, or keep him where you can observe him at all times, so that you can reassure him, if needed.
What makes this period even more difficult is the fact that many pups are reaching sexual maturity, which again alters their personality. This is a time when once again the pup is going to try to assume what he considers to be his rightful place as "pack leader". You must be firm in insisting that you will retain this position, while at the same time avoid a real trauma that is going to remain with him if he is in the "fear of new situations" period.
If the pup has been raised according to the charts on the preceding pages, you are going to have fewer problems with the sexual maturity than you would have with a pup that has been raised permissively.
According to Dr. Michael Fox, "When permissively raised pups reach sexual maturity they may become even more difficult to handle, showing extreme indifference to their owners and violent aggression when disciplined to forcibly restrained. Humane destruction is the fate of many such dogs; owners who wanted to raise their pet permissively should have chosen a more submissive and sociable breed or have had it castrated early in life to reduce the chances of sex-related aggression and dominance fighting that is associated with maturity."
As stated in the beginning of this article, raising a litter of puppies properly is difficult enough, but multiplying that by six or ten, or even twelve means devoting full time to the task. But, the rewards are great, especially when your new puppy owners call you to state "I never knew owning a puppy was such a joy. Other dogs I have owned were pests, but this one is so good, and so obedient, I can hardly believe it".