More recent evidence proves that the major contribution to the smell of flatus comes from a combination of volatile sulphur compounds (vsc).[5][12] it is known that hydrogen sulphide (h2s), methyl mercaptan, mm (also known as methanethiol, mt), dimethyl sulphide (dms), dimethyl disulphide (dmds) and dimethyl trisulphide (dmts) are present and cause the smell.Those compounds are the one percent that cause the smell.
Symptoms include a whitening of the lens, which is a clear part of the eye needed for focussing, and the problem impairs sight and may even lead to blindness. The whitening or cloudiness is opaque and thus cannot be seen through. Inherited cataracts can occur at any age in the affected dog.
Dogs tend to rely more on motion than focus, though. They have trouble seeing objects closer than about 10 inches and must use their noses to find the kibble that spills out of the bowl. The visual acuity of dogs is about 20/75, although the German shepherd, Rottweiler, and Schnauzer appear to be even more nearsighted.