A vet suggested it. I have had numerous discussions regarding platelet counts with vets. I personally believe this guideline was a result of "not good" breeding or chronically comprised greyhounds who had tick diseases. These guidelines were established in Texas as a result of a vet who was also a greyhound racing breeder.
It's a major issue with me. I have seen my greys have lower platelet counts and when put on doxy, see those platelets come up to reasonable levels. There is something we are not seeing or allowing for.
When you have a greyhound with lower platelets and brusing, that to me is a serious issue and I'd have them on doxy and do a tick panel.
I find it interested that many of the older greys I've had have higher platelet counts than the younger ones. Many of my older (meaning in the past and they were old) except for my first two greys, have had platelet counts of over 200,000.