I have owned LGDs for 15 years and altho’ I first got purebred Pyrs bc of their rep as “calm & good with young children as well as livestock” (I had 3 yo twins at the time), what I personally discovered ab the Pyrs is that both of your main concerns are valid at some point or another (which is why I no longer use Prys…read on)
1). My purebred Pyrs did indeed have a wanderlust that regularly took them outside our fencing on ‘adventures’, so instilling a healthy respect for fencing at a very young age is PARAMOUNT. Once your dog is big enough to really start doing his/her job, it’s too late. At 100 lbs, a dog can pretty much do what he wants & fencing becomes a ‘suggestion’ not a hard & fast boundary; so puppyhood is the time to institute that respect. As puppies they will test fencing by digging underneath or pushing through holes or loose gates, so the best & most reliable “correction” I have found is with electricity. You can’t always physically be there every time bad behavior strikes, but electrical fencing can. That said, my mature 140lb LGD will still take a hit of electricity in pursuit of a predator…if he is after a fox or coyote, we will hear the “yip!” as he clears the fence & hits the hot wire. He always comes back after he has run off the offender, but not until he has made his way around the entire outside perimeter & peed on every living tree & bush as a reminder to any other predators not to get close. He always gives us a tired, withering look when he returns as if to say, “you 2-legged idiots…of course there’s no danger INSIDE the fencing, it’s OUTSIDE the fencing where I’m needed!” To fence train, start with puppy inside a small area that you can electrify so every time he ‘tries’ a fence, it ‘reminds’ him to stay back. It may sound a little harsh, especially with a cute puppy, but these early lessons will pay off big later. Enlarge the area over time & if you see him starting to disrespect fencing, backtrack & put him where he will get a ‘correction’ if he messes with fencing. Raising a good LGD is not a hands-off endeavour…it takes some effort in the first year +, but once you have laid down the ground rules, as the dog matures & his centuries-long breeding becomes evident, you will have a truly masterful guardian who will give both human & animap predators pause about approaching.
2). Harrassing young animals during puppyhood is part of the growing-up that all LGDs do in their first year & it’s up to you to make sure it doesn’t end tragically. That LGD puppy should never be left alone with younger weaker animals that he could harm. I made a tragic mistake one summer with a 1yo Pyr puppy & a young llama about the same age. First off, never put a dog & llama together in same pasture…llamas do not like canines & are used as guardian animals themselves so what was I thinking, right? I thought raising the 2 babies together…blahblahblah, stupid human thinking she could reverse centuries of innate breeding…I thought for sure that even if the dog chased, the llama was swift enough to get away; but I hadn’t counted on the dog’s endless energy to chase. He never caught the llama but he literally gave it heat stroke bc he constantly wanted to “play chase”. It was all a game to him & he literally wore the young inexperienced llama out. I will carry the guilt of the death of that animal to my own grave, so believe me when I tell you that a young unsupervised dog’s appetite for stalk-chase-capture, even in a supposed guardian dog, is hard wired, boundless & must be shut down early & often. Many times this can be done by having an older & experienced LGD (never worked for me…my older female just sat & watched as the younger one tried to stir up sheep) OR by only penning the young dog with older livestock who won’t put up with any misbehavior & will dominate the dog by charging it. I have a very cranky old doe who will “straighten out” almost any young canine who gets rowdy with her. She has “taught” several of my young LGDs about how not to act around livestock & while it is sometimes difficult to watch the education (she dominates by butting & sometimes rolling the dog who yipes & retreats), she has been very effective. The dog learns to walk slowly & with deference through the herd & not to make trouble. I had concerns that such treatment would produce a cowering dog, but never fear. Reliably, once mature & faced with a real predator threat, the dog & the goat traded places in the hierarchy & the dog protected the very animal that had been “schooling it” so harshly for months.
Truly amazing to witness. When my dogs were young, no mstter the breed, they ALL tried to harrass young livestock (both lambs & kids & also chickens, altho the latter could generally run faster & fly up out of reach or over fences). That said, once the dogs matures, they have been magnificently effective at keeping any sort of predator, both 4 legged & 2 legged away. An LGD is not fully mature until age 2, so there is always going to be a period of behavioral exhuberance. That’s why God made parents & consider yourself a canine parent. You don’t have to “train” an LGD to do his job, but while he’s young & maturing, you DO have to make sure he has fewer opportunities to do the wrong thing, ie: curtail him & keep him out of trouble until his brain has time to catch up to his body. Same as with human youngsters. I promise that if you do this, you will have YEARS of worry-free guardianship of your herds & flocks. There is no more perfect predator repellent on earth than a good LGD. I prefer the Akbash…a Turkish breed, same all-white coloring, curlier tail, overall bigger body, less overtly friendly than Pyr…just a little more standoffish & less of a wanderer.
Best of luck to you.