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.

Colour vision depends on the presence of colour-sensitive cells (called cones) being present in the retina at the back of the eye, and also the brains ability to interpret the nerve signals transmitted from these cells 

The cat is a predatory animal that often hunts by night, or in dim lighting. As a result it has evolved an eye that is especially adapted to "seeing in the dark" - although some light is actually needed to see anything. 

There are two types of light-sensitive cells in the retina :

• Rods - which are more sensitive and can detect small glimmers of light 
• Cones - which provide more detailed vision and detect colour. There are three types of cone which absorb different colours of light - red, green and blue

Humans have a ratio of about 4 rods for every cone, whereas the cat has about 25 rods for every cone. From this we can conclude that cats have better vision in dim lighting, and that they probably can not see as much detail as us due to the relatively low number of cones.

Scientists thought cats were probably unable to see colours for many years, but we now know that they do have green and blue-sensitive cones in the retina and they can be trained to recognise different coloured objects including red, blue and white. However, green, yellow and white probably appear very similar and red objects probably appear to be grey as cats do not seem to have red-sensitive cones.

Updated October 2013