Wanted to share our experience so far. We adopted in April 2019 and gave our girl (Sally) Drontal and Advantage Multi monthly, on a schedule staggered weekly (started with Advantage Multi, started Drontal 3 weeks later, another dose of Advantage Multi 1 week later, another Drontal 3 weeks later) for about 3 months. Her poops have always been on the verge of pudding, but were holding shape pretty well by the end of this course of treatment. She started having a really loud gurgly stomach with no appetite in the morning and some diarrhea a couple of weeks ago and we finally brought her (and a sample) to the vet this week and she came back positive for hookworms.
All the vet has prescribed is Panacur for three days, and then repeat for three more days in a couple of weeks. After reading this thread I'm a bit worried that this isn't going to be enough, especially given the course of treatment with Drontal and Advantage Multi that clearly didn't get rid of them (it's unlikely this is an environmental thing: she doesn't poop in our yard and is rarely around other dogs for much time unsupervised). I'm also a little concerned because when I asked the vet if she should be on Advantage Multi in addition to the Panacur, the vet told me that Advantage Multi was only for fleas and ticks...
So we're going to reach out to our adoption group for advice and may be looking for another vet who is more versed with greyhounds too. In the meantime, I'm planning on getting a bunch of doses of Advantage Multi to start her on that again. And once we're through the Panacur and get her re-tested, if she's still positive I may get some Drontal as well and try the Prison Greyhounds program, or something similar. Latest link to it is here: https://prisongreyhounds.org/Hookworm%207-2018.pdf
Edit: Thought I should share a photo too since this is my first post :).