Many toxic plants are unpalatable, so animals avoid them where possible. However, this is not always the case; locoweeds, for example, are addictive and once a horse has eaten them, it will continue to eat them whenever possible, and can never be exposed to them again.
Micrograph of melanosis coli, with the characteristic mucosal lipofuscin-laden macrophages (brown). Melanosis coli, also pseudomelanosis coli, is a disorder of pigmentation of the wall of the colon, often identified at the time of colonoscopy.It is benign, and may have no significant correlation with disease. The brown pigment is lipofuscin in macrophages, not melanin.urther information: Factitious diarrhea. The most common cause of melanosis coli is the extended use of laxatives, and commonly anthraquinone containing laxatives such as Senna and other plant glycosides.
The causes of this kind of Melena are the same as when the stool is tarry. In addition, this type of Melena is also associated with anemia which is causes due to the loss of iron along with the blood.black, tarry, sticky and foul-smeling stool that is usually caused by gastrointestinal hemorrhage.elena can also occur due to bleeding ulcers. Ulcers are sores that develop in the lining of the stomach due to infection by Helicobacter pylori bacterium. Drug overdose can cause tarry stool as well. Prolonged use of pain relievers can irritate the stomach and cause stomach ulcers and melena.