An endoscope is a flexible fibreglass tube which enables us to check the inside of certain organs through a light source and a lens.
In the case of horses we especially use this device to get an image of the airways in case of respiratory problems like laryngeal paralysis or recurrent airway obstruction (RAO).
We can also use an endoscope to cover mares by hysteroscopy or endoscopy. This procedure involves looking with the endoscope just against the oviduct and injecting the sperm (mostly frozen sperm) locally in very small quantities.
We can also check the stomach of foals for gastric ulcers with a very thin endoscope, as described in one of the articles.