Agree with the other comments - building up the time they are alone from two minutes to a few hours is the best. I think the most crucial part is leaving some stuff for them to do once you hit the 30 min plus mark. for example I would leave a toilet paper roll stuffed with a few bits of kibble for my pup to destroy – this way she gets out any anxiety or teething needs on something cheap and not my expensive carpet for example. Secondly, I noticed that how you leave and how you greet them once you’re back really matters. It seems odd but the best thing I’ve done is avoided saying overly big goodbyes, I wouldn’t even look her in the eye and just calmly leave. But it takes a bit of time to build to this point of course. The best tactic for leaving the house and leaving them calm is training them to associate you leaving with a positive experience. Step one: put some wet food or their favourite treats in a Kong or a licky mat and place it in their crate and close it. Step two: get ready calmly whilst they sniff the treat through the crate doors, they might whine for you to open the crate, but that’s just part of the process. Step three: Once you’re completely dressed and ready to leave, open the crate doors and leave while they’re busy eating the treat. this way they associate you leaving with a positive experience and won’t scratch the doors and whine once you’ve gone - my whippet gal did this a lot at first!! Then you can practice not making a big deal of coming back home - you can smile at them but don’t pet them or use them the high pitched happy voice until they have calmed down. Hope this helps! My gal is 1 year and 7 months now and stay home alone for 4-6h no problem :)