They don’t all take 3 months off work to sit with their dogs?
I tend to think this the is one of those 'self selecting' things. Those people with older dogs that they had from puppies fit into 1 of 4 scenarios:
- They planned and so were able to be home or arrange suitable cover care for when they were out
- They got lucky and got a dog that was relatively ok with being left
- They got a dog that hated being left, was very distressed BUT got lucky that the distress did not last into adulthood. Maybe they never even realised HOW distressed the pup was and eventually it just got used to being left.
- They got a dog that hated being left, was very distressed and never got used to it, they got rid of the dog because they couldn't cope with the problem.
What that means is that a large % of people feel able to say 'I got a dog and left it alone for 2 hours a day and it was fine'. As you're finding out, that's not guaranteed (or typical).
Slow and steady is the way. If you try to push the dog quicker than she can cope with you risk setting up lifelong behavioural problems. Before she can be left for any length of time, she needs to know:
a) she is home. After just a day or two she will not recognise that where she is as home. That takes time.
b) she is safe. That means she needs more time to get used to her environment plus needs to have outgrown the baby phase in which her instinct is telling her that being left alone = unsafe. As it would in the wild. She needs her mum. Her mum isn't here so she needs you.
c) you will come back. For her to learn this you need to break being left into tiny increments, a few seconds in the next room, building up to a minute in the toilet, building up to 5 ins in the garden, to 10 mins popping to the shop, to 20 minutes going for a run - and so on. This could take weeks/months.
d) that being left alone is not scary - going too fast will teach her the opposite, that being left alone is awful and results in her being so distressed she vomits (something she has started to learn already).
Brace yourself, OP - it is going to be a long and bumpy ride! In my experience, once you crack one behaviour thing, another thing appears and you have to work on that. This continues until the dog is fully mature (18 months / 2 years).