I was goingto post exactly the same thing for North Goa!
I know of one place valled Greenlands in Cavelossim, or close to.
I went riding there last year on their equivalent of our Red Rum. A retired Race Horse - known for his galloping.
Very Fast Horse indeedy.
You might be able to ride horses in the North but not in the beach, its worth looking around when your there tho.
Please let me know if you find anything in the mean time !
Bobbi