I have been in the veterinary field since I was 14 years old - I won't tell you how many years that has been but it's been more than a minute. Things in veterinary medicine have changed quite a bit since I first came into this career. I could spend many hours discussing all the changes I have witnessed but today I am focusing on one big one - puppy socialization.
When I was first working as a veterinary assistant I got to hear my veterinarian's new puppy talk many times - so many in fact that it became ingrained in my mindset. At that time the major focus was on disease prevention and vaccine schedule and EVERYONE was told not to take their puppy outside until they received all of their vaccines. Basically what this meant was that these puppies should not see the outside world, where scary diseases were lurking, until they were between 4-5 months old. And as veterinary professionals we felt we were doing the best thing for these pets and their owners because we were ensuring these puppies received their proper vaccinations to keep them immunized against things like Parvovirus, Bordatella and Distemper Virus. And so for years there were puppies who were never exposed to other pets, other people, different situations, loud noises etc etc.
The reality of that situation is that we were depriving these puppies of so much by keeping them isolated until they reached the end of their vaccination schedule. As veterinary medicine has progressed and understanding of the canine brain and behavior has advanced, we have learned that puppies need to be socialized during that time period. Puppies are born without any fear however around 5 weeks of age they begin to develop a fear response. If puppies are introduced to new things in a negative way they will remain fearful of it - however if they are introduced to things in conjunction with positive reinforcement these puppies will create positive associations with these stimuli. The canine brain has a distinct window of opportunity to create these positive associations - ironically this window closes around the same age that vaccine schedules end. Therefore, if we wait until 16 weeks to say that a dog can start to socialize we have missed their entire window of opportunity - meaning that these pets will create fear responses to everything they come in contact with after 16 weeks of age. That's not to say that a dog cannot create positive associations later in life, but it takes more work and patience to create them.
Behavior issues are much more common in dogs that lack proper socialization - these are the dogs that become labeled as 'caution' or 'fractious' at the vet office when in reality they are truly just fearful. When dogs become fearful their responses can range from hiding and trembling to becoming aggressive, because they feel they have no way to escape a situation that is making them uncomfortable. When this happens these dogs are handled less and less which contributes more and more to their fearful behavior. Behavior issues are the leading cause of surrender of dogs to shelters and rescues before the age of 3. Ironically the risk of contracting infectious diseases during the first 16 weeks of life is lower than we once thought - yes, there are cases of puppies contracting parvovirus and distemper virus but to be truthful, most of those are shelter situations or high volume breeding situations. They are not the puppies who are being properly socialized so that they can create positive associations with other pets, people and situations.
Do I tell my clients to go crazy and take their juvenile puppy everywhere with them during this time? Of course not! What I do tell them is to socialize their puppy in a smart way. What does this mean? This means using good judgement as to where those pets go - my recommendations are to avoid places where we can't get a feeling on how other pets in the area are cared for. In my mind these places include dog parks, large pet super-centers/stores, large concert venues where many pets are going to be and we don't know if they have been cared for properly. However, great places to take your pet include friends and relatives homes where pets live that we know are well cared for. This allows pets to socialize in a manner that is safe but effective. Another option is to look for advertised puppy socialization classes often held at veterinary hospitals or small training centers - often these are specifically for socialization purposes and not for training purposes. Despite what most people think, veterinary offices are generally very clean places and are not harboring infectious diseases because so much thought is placed into floor materials, cleaning products etc to keep our hospitals as clean as possible. Having puppy class at a vet's office is a great option to socialize pets and also create fun and positive associations with your veterinary clinic for your pet.
I always recommend chatting with your veterinarian about best recommendations for your individual pet - ask them what they recommend for socializing your puppy - if you have an older dog inquire about things you can do to help them reduce their fear of certain stimuli. It's never too late to expose your dog to new things as long as we make each exposure fun and positive.