Other health concerns
Primary Lens Luxation (PLL) is the partial or complete dislocation of the lens, and normally occurs at 4 years of age. Clinical signs are not visible before the age of 3 or after 7, so a visual eye test should be carried out annually. It will normally affect both eyes, with one going some weeks or months after the other. Research suggests a recessive inheritance in Border Collies and some terrier breeds, although it is not specific at this stage. It is known to be non-congenital, ie not there at birth. It is the most common cause of secondary glaucoma, and so can lead to blindness and loss of the eye. However, it can also be a secondary complication of primary glaucoma. Treatment is the prompt surgical removal of the lens.
Central Progressive Retinal Atrophy (CPRA, also known as Retinal Pigment Epithelial Dystrophy, or RPED) normally starts around 18 months of age, and is caused by the build up of waste material from spent photoreceptors (the rods and cones that enable any mammal to see). The material would normally be metabolised by the epithelium to be excreted in a healthy dog. The build up of waste lipopigments then compromises the effectiveness of the retina.
The dog may become unable to work on bright light, although vision in dim light may not degenerate until the disease is quite advanced. In fact, an affected dog may not go blind, but may retain a degree of peripheral vision.
This disease is not to be confused with General Progressive Retinal Atrophy (GPRA – to date, not recognised in Border Collies) which does always result in blindness. The inheritance is unknown as things stand, but everything indicates that it is complex, and that environmental factors have an influence. It is thought that poor diet and lack of Vitamin E can affect the phenotype.
Primary Glaucoma has recently been identified in Border Collies. It is an extremely painful condition, where increased pressure of the fluid inside the eye causes damage and ultimately blindness and loss of the eye itself. It is a degenerative process, and once the optic nerve is has started to deteriorate, the vet will only be able to slow progress, they will not be able to save the sight.
Gonioscopy is not recognised as an official test for the Border Collie yet, although a number have been carried out. Mode of inheritance is not yet determined, although research in other breeds suggest it is genetic.