國外作Interbreeding已經有很久的歷史了!大部分Interbreeding的牛頭梗都over size但是頭型的表現會較純迷你型的優秀!遺傳性疾病也較少,PLL就是其中的一種. 英國,澳洲的迷你就是因為這個問題所以有做Interbreeding, 主要原因是為了擴充迷你的基因庫,來解決這個問題.

PLL Description:
This is a condition where the lens is partially or fully dislocated from the threads that hold it in position within the eye. These tiny threads, sometimes called ligaments are known as zonules and it is they that weaken and break causing this condition. How quickly and how many break determines the speed of onset of this condition. Using normal ophthalmic instruments (such as your own vet may possess) it is difficult to even see these small threads. What the experienced ophthamist (not your own vet) should also be looking for is a wobble in the lens as the dog moves his head around. This indicates that the zonules are becoming weak. Weak zonules is called subluxated, completely detached (luxated)

The term luxation means the displacement or dislocation of the lens from its normal position in the eye (i.e. behind the iris and on the line of vision) There are several causes of lens displacement,for example ocular diseases such as glaucoma or cataract. However, the most common form of the condition in the United Kingdom is inherited and is called primary lens luxation. It is seen principally in the terrier breeds, may affect either *** and arises spontaneously in middle age (3 - 7 years). Sometimes both eyes are affected at the same time but usually there is an interval of weeks or months in between. Once one eye is affected the other will invariably follow sooner or later.

In an affected eye, the lens usually moves forward, coming to lie behind the cornea. Occasionally it may pass backwards into the vitreous body. Sometimes it may move between the two sites. An anteriorly luxated lens causes an opacity (cloudiness) of the central corne

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