I stopped reading horse magazines a long time ago when I realized that all they do is repeat themselves with the same article, year after year, with different photos and different wording. After you know how to groom and tack up, keep your horse cool in summer, keep your horse warm in winter, know your horse breeds, know the show rules, know the trail riding rules, know when to call a vet, keep your heels down, and know how to haul a horse, those magazines aren't really worth your dollar.
The last magazine I subscribed to and still read (many subscriptions I had for years, I just hardly read the magazines when they came in) was Equine Health, I believe. You can always learn from a magazine like that.
Horse health has always intrigued me so this magazine was right up my alley. At least, I believe it was Equine Health. It was a while ago. If it wasn't specifically Equine Health, it was deffinitely a health related magazine.