[header] How to know if your dog is losing its eyesight [title] Look for cloudy pupils. [step] When a dog's vision begins to suffer with age, you may notice a change to the eye color itself. Cataracts are often a cause of loss of vision related to age, and can be easily seen by looking at your dog's eyes. 
[substeps] Cataracts are marked by a cloudy appearance around a dog's pupil. Monitor your dog's eyes frequently as it ages, as cataracts are easier to treat and reverse if caught early.