An endoscope is basically a long tube with a light, through which the vet is able to see into inaccesible places, such as the stomach, airways, etc. The most basic endoscopes are just rigid hollow tubes with a lens system rather like a telescope. By shining a light down the tube, and looking through the eyepiece, the operator can see a magnified view of what is at the other end of the tube. More sophisticated endoscopes have fibreoptic fibres which conduct the light to the far end, which gives much better illumination. The most useful sort have not only a fibreoptic light source, but also fibreoptics to return the image to the eyepiece. The great advantage of this is that the tube can bend, enabling visualisation of organs deep inside the body.
We have several endoscopes at the practice. Most commonly, we use flexible fibreoptic endoscopes for looking in the stomach and small intestine of patients with vomiting or diarrhoea problems. Sometimes a diagnosis can be made just by looking. Often biopsies are taken, and a pathologist's report diagnoses the cause. Occasionally the cause of the problem can be removed there and then - for example, we recently removed two socks from a dog's stomach using the endoscope. This saved the patient from having major surgery.