A year or so pre-COVID, I was headed up toward Mt Langley about 2km before the PCT intersection (I think) and I saw a dog trotting unleashed toward me. It was one of those aggressive dogs, not sure of the breed.
It stopped. I stopped. Then it growled and showed its teeth as it slowly approached me. I started to climb a tree.
Then, a pack of dogs of the same breed followed over the trail all off leash, along with the owner.
The owner seemed annoyed with me for 'trying to hide from the dog'. WTF?
They all passed me and went on their way.
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Years ago the Shepherds' Pass trail was closed to human exploration because the native species (sheep) had abandoned the area. Not saying it was due to irresponsible pet owners, but it very well could have been.
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When you sign a permit for Mt Whitney you have to agree that no pets are allowed into SEKI. It is one of those boxes you initial. Yet, some hikers ignore this.