Systemic diseases of the dog and cat frequently cause ocular signs.  The basic ocular examination is non-invasive and can be performed with relatively inexpensive equipment. A thorough ocular examination can therefore be a powerful tool for the detection of systemic disease. This presentation discusses some of the ocular manifestations of systemic disease seen in dogs and cats, however is by no means extensive, and many more interesting examples can be found in the primary literature and textbooks!