Updated: Dec 1, 2020
One thing that comes up when I'm working with clients who have done a great job with socialization and raising their puppies is when their dog is an adult and suddenly spooks completely out of no where. I'm boarding a Rhodesian Ridgeback this year that I've known since she was 8 weeks old. The owners take her everywhere, she does both daycare and dog parks, she went through group classes, and a three week training program. She sailed through the time I brought her with me to Lure Coursing. She's been shown in conformation before. The owners have done a really spectacular job with her, but it's almost Halloween and the decorations everywhere are posing a problem.
Kona the Ridgeback was very young last Halloween and very likely was not exposed to the oddity of blow up decorations, looming skeletons, and more. When she saw the first one on my street she went into full blown alert mode, barking and barking, and let me tell you her bark is deep. This is an excellent example of a socialization gap (she's also in a fear period, which doesn't help matters).
Despite our best intentions and most meticulous plans, there is always going to be something that we missed. That could be because it didn't occur to us to take out holiday decorations when it's not the season for that holiday. Or, it could be because life just doesn't cooperate. When I brought home Ash and Anubi, I was doing both dog boarding and fostering relatively frequently. As such, they got very accustomed to random dogs entering their house. When I brought home Amalu I started doing more boarding and board and trains, so she had a similar experience.
However, when I brought home Amidi, I wasn't doing much boarding at the time. This meant the first time she experienced a dog coming into her house was the first time that we boarded a dog when Amalu was a puppy. And that was very hard on her. She's fallen into the routine, but it took quite a few boarding dogs before she understood what was happening and even longer before she accepted it comfortably (she tended to spend most days curled up on her bed on the couch avoiding the other dogs). Now, while watching Kona this week, Ami has cuddled with her, played with her, and shared her toys with her. Her level of comfort is always going to be dog dependent, but she understands the system now.
Similarly, I discovered when I took Anubi to Tennessee that Ami had never boarded anywhere before. She is my happy outgoing girl, but when my parents watched her she was anxious and very uncertain. It hadn't even occurred to me that it would be a problem because she's so stable, but because she'd never done it before, particularly never having done it as a young puppy, it was hard and took her a long time to adapt.
For Anubi, his big socialization gap is dog shows and trials. He never experienced them before 8 months old and his level of comfort in those situations speaks volumes. The more we trial, the more he gets used to it, but it took a huge amount of exposure before he started to relax in show and trial environments.
For Amalu, who is my COVID puppy, it's mostly having people over to the house that she's missed out on. I'm honestly a bit of a hermit, so I don't have many people over anyway, but we've had pretty much no one over since I got her and I know if I had someone over now she'd struggle. I think trials and shows will be less comfortable for her than Ami, but we were able to get out to a limited amount this year, so she's seemed relaxed thus far.
My point, when talking about socialization gaps, is no matter how well you plan, you're going to miss something. I sure did. It's not the end of the world. It will be more work and exposure to get your adult dog comfortable with a specific new and novel thing, but it happens. Do your best, plan ahead, and then do your best with your adult dog to recognize what you missed.