Some of this is not a training problem, and treating it like one wastes time your dog may not have. If they are distressed when you leave, if they growl or guard their food, their toys or you, if they are frightened on the lead, or if anything about them changes suddenly at any age, contact your vet the same day. A tip from a website, ours included, is not the answer. If it cannot wait, contact your nearest emergency vet now.
With a Saluki, watch for change. Failing sight, an underactive thyroid and a weakening heart all show up in how they behave before they show up anywhere else: bumping into furniture at dusk, hesitating on stairs they have always taken, going quiet, breathing faster while they sleep, losing interest in the run they used to love. Bloat (GDV, a twisted stomach) is most common in large, deep-chested dogs, so skip walks and hard play shortly before and after meals. A swollen, tight belly, retching with nothing coming up, sudden restlessness or drooling is an emergency: contact your vet now. The other changes are easy to put down to age, which is why they are worth raising early.
They'll keep your side of the bed warm. If they stop wanting to leave it for their run, tell your vet.