4 Months to 6 Months
At 4 months old, pups begin to teethe and chewing becomes an issue. This is a stage where, like young children, pups want to put everything in their mouth. What you, the new owner, have to do is "go with the flow." That is, accept that puppy
chewing is an inevitability. Do not try to prevent it but rather redirect it onto appropriate objects. For example, if you catch the pup chewing on an electric wire, issue a short sharp command such as "Out," abruptly remove the wire from the puppy, or the puppy from the wire, and relocate him onto an acceptable chew object, say a puppy-sized Kong or olfactorily-enhanced rope chew toy.
At this stage of development, puppies often exhibit fits of "the maddies" and periodically tear around the house, running across the furniture, practically bouncing off the walls. This is a release of their natural exuberance and is to be expected. However, you shouldn't have to tolerate destruction of your home. One way to circumvent the latter is to puppy-proof your home to prevent the damage or, when possible, to herd the youngster outside to blow off steam.
At about 5 months, if you have more than one pup, you may find that play becomes more aggressive and associated with some nipping, growling, and general displays of dominance. Many males, and some females, will begin humping each other at this stage as they rehearse for their adult roles. Such behavior is acceptable as long as it is not directed towards you. If you find yourselves the substrate for any aggressive behavior or leg humping it should be immediately addressed in the manner described above.
Although you should have been training your puppy from the time you acquired him, the 4 to 6 month window, with vaccinations in place, is the usual time for formal puppy training classes outside the home. Such classes are extremely helpful as long as they are conducted in a non-confrontational way. Puppies can be taught to sit, lie down, wait, stay, leave it, and other such useful commands that will stay with them for the rest of their lives. Once these behaviors have been learned they can be reinforced, even insisted upon, periodically throughout life to make sure that they stay well-honed.Conclusion
The 8 week to 6 month period of puppy development is a thrilling one in which development is rapid and the effects of proper schooling are immediately apparent. This period of development is almost as important for the puppy as the first two months of life. Good coaching goes a long way toward producing a happy, respectful, and well-behaved juvenile and later, adult dog. And the reverse is also true that lack of attention or improper training will leave its mark. The thing that many new puppy owners fail to appreciate is that puppies, during this period, are really quite like human toddlers. They rely on us, they need us, they look up to us, and they learn from us. During this time, they need a lot of our attention and time if they are to be properly looked after. It is not sufficient to acquire an 8-week old pup and imagine you can simply tend it like a house plant and watch it develop and blossom. No, it requires our attentiveness, physical presence, and guidance, to produce the kind of adult dog that we all dream of.