Acute blindness is a frightening experience for both the owner and animal. This lecture will discuss the most common ocular diseases causing acute blindness and the approach to a complete ophthalmic examination optimizing diagnostic accuracy. We will explore glaucoma, diabetic cataracts, retinal detachment, posterior- and panuveitis as well as optic neuritis. Sudden acquired retinal degeneration syndrome (SARDS) is another canine disease that causes acute blindness and we will review diagnosis and treatment options. Animals presenting with acute blindness require rapid diagnosis and intervention to optimize the chances to preserve visual function.