The United States Pony Clubs, Inc. has partnered with Merck Animal Health to bring you a series of blogs based on current horse health. This first post was written by Dr. Bryant Craig, DVM, Merck Animal Health Equine Technical Services Veterinarian. While all intestinal parasites are concerning, one of the most lethal threatens horses during their first 18 months of life. The Suspect Ascarids, also known as roundworms, are migrating parasites that travel through the bloodstream to the horse’s liver and lungs during their juvenile stage before returning to the small intestine to develop into a mature parasite. Because of this migration, clinical signs of an ascarid infection can vary…