In older adults, mild thickening, calcification, or both of a trileaflet aortic valve without restricted leaflet motion (i.e., aortic sclerosis) affects about 25% of the population older than 65 years. Calcific aortic stenosis (Fig. 1) , however, affects approximately 2% to 3% of those older than 75 years.alcific aortic stenosis, formerly referred to as degenerative, affects trileaflet aortic valves, often in patients with other risk factors for atherosclerotic disease. The aortic valve leaflets undergo an active disease process, with lipid deposition, inflammation, and osteo-calcific changes.
The three most common toxic weeds to horses that may be contained in hay are: Hoary alyssum, wild parsnip and poison hemlock. 1  Hoary alyssum - Hoary alyssum is a perennial weed. 2  Wild parsnip - Wild parsnip is mainly found in ditches and fields and is a biennial and is poisonous to horses. 3  Poison hemlock - Poison hemlock is poisonous to horses.
Most horses are domesticated, and are protected by people from their predators, or natural enemies. Almost all horses that live in the wild are descended from ancestors that once belonged belonged to people. These domesticated ancestors escaped and became wild again. Thousands of years ago, before horses were domesticated, their main predator was the wolf. Wolves were one of the few animals that were fast enough and smart enough to chase, catch, kill and eat horses. Even now, the wolf is one of the few predators that eats wild horses. Grizzly bears and mountain lions may also occasionally attack a horse.