Clinical descriptions for the Tibetan Terrier appear the same as late-onset PRA in other breeds. The mode of inheritance appears to be autosomal recessive, with diagnosis around 5 years. Age of onset not precise, as there is insufficient early-age data to confirm. It is very likely that the first clinical signs appear earlier than 5 years, as owners tend to notice the onset once the disease has impacted vision. No mutations have previously been associated with PRA in the breed. The Tibetan Spaniel seems to develop the disease either later or more slowly, as diagnosis averages around 7 years. It may be that there are other, unknown forms of PRA in the breeds.