You should seek the advice of your veterinarian if your pet is ill as only he or she can correctly advise on the diagnosis and recommend the treatment that is most appropriate for your pet.

One of our most precious senses is sight and unfortunately pets can be born blind  - or lose their sight later in life. What are the causes and consequences ? 

Very  few animals are born without sight due to a congenital absence or deformity of the eyes, or of the nerves which carry messages between the eye and the brain, or due to abnormalities in the brain itself. Such animals do not usually survive, but if they do they need life-long protection from dangers in their environment which require sight to identify and avoid.

Blindness can be :

• Partial, or
• Complete

and it's onset can be :

• Sudden, or
• Gradual

Of course to be totally blind both eyes must be affected and animals live a normal life with only one functioning eye.

Animals generally cope very well with slowly progressive loss of sight, even if it becomes complete. They adapt very well to their environment and, providing owners do not move furniture and other objects around, they learn where obstacles are and rarely bump into them. For many pets vision is not the main sense that  they rely on - hearing and smell are just as important.

Sudden onset blindness can be more difficult as it can lead to disorientation and panic. With time however, even these animals will adapt very well to their new predicament.

Blindness can be caused by many disorders of the eye, the nerves connecting the eye to the brain, or the brain itself. Some examples are:

• Advanced pigmentation of the front surface of the eye (the cornea)
• Advanced opacity due to cataract formation in the lens
• Diseases of the light-sensitive part of the eye (the retina) eg retinal atrophy or degeneration
• Increased pressure within the eye - called glaucoma
• Trauma to the eye or head
• Damage to the retina due to generalised diseases eg high blood pressure (hypertension) which can be primary or secondary to other diseases such as kidney failure, and can cause retinal haemorrhages, or detachment of the retina.
•  Brain tumours

Recognising blindness can be difficult with gradual onset blindness because animals cope so well, however tell-tale signs are a reluctance to walk around in unfamiliar places, bumping into objects, uncertainty when negotiating steps or occasional disorientation due to loss of bearings. Loss of visual recognition of owners may also be obvious and sometimes a blind dog will refuse to move and barks until the owner contacts it by voice or physical contact. In old animals blindness can be complicated by a loss of cognitive senses including  recognition of the environment and owners. 

Some causes of blindness can be successfully treated, for example a cataract lens can be surgically removed and, provided the retina is intact and functioning, sight can be restored. Some forms of brain tumour can also be successfully treated if they are localised and accessible. On the other hand some diseases cannot be treated satisfactorily eg retinal degeneration, and sometimes an underlying cause eg kidney failure must be treated as well. 

If you are concerned that your pet might be losing it's sight ask your veterinarian to examine it because the earlier the cause is identified the better the chances of treating it successfully.

Updated October 2013