Just a quick update:
I brought Luke back to the vet today. He's lost 8 pounds in the last 9 days, the vet drew a blood sample and we should have the results by Saturday, She's thinking it's might be Addison's , the blood test should help us figure out what we're dealing with. on that note the prescribed him steroids see if that helps him improve.
I asked about Luke's initial Hookworm test last month and she said he had a very small amount of hookworms at that time.
Thank you all for help, its been great to be able to talk to other greyhound ownersto help luke get better.