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.
It is very important to regularly clean and check your Shih Tzu's eyes. Some dogs have allergies which causes excess discharge around the eye. Older Shih Tzu's are known to develop cataracts which can be corrected with surgery. If not treated, the dog may become blind in the eye that has the cataract. The distinctive large eyes can easily be scratched which may cause an ulcer.