I have read somewhere that dogs have a different colour spectrum to humans and they see blue and yellow but do not see red.
Does anyone know anything about it here?
My dog has difficulty seeing his red ball in the grass but i thought it was because it is a similar shade so it disappears against the green. Obviously I was wrong but am very interested in this subject.

>My dog has difficulty seeing his red ball in the grass but i thought it was because it is a similar shade so it disappears against the green.

This will help. The red ball is probably a similar tone (not 'shade' - there's a difference!) and so appears to be vry similar in colour. This usually doesn't matter because dogs use their noses much more than their eyes to find things - even dogs with both eyes removed will be able to find things through scent.

There was a time when we were told that dogs did not see any colour at all but then they decided that the receptors in a dog eye were the same as ours - it is now possible they have decided that dogs can not see red. Not sure it matters as I can never understand how we know what we see as red is the same as others see when they think they see red, we see what we have been told is red but have no way of comparing it to what other see as red - if you see what I mean and do not see red at my reply :-)

Interesting link.....it helps to explain why our old Rott used to go ballistic in her crate when we passed a red or yellow lorry but far calmer with green and blue stuff.
Chris

I can't say I have ever seen any colour preference in the Yankees, but two of the pugs react very stongly  .... to PINK!  At first it was only Puglet, and being completely soppy about her I put it down to her being very girly.  She always went for pink toys first, and when I am sewing insists on "trying on" anything in pink - bit hard when it was something like a cushion cover, but I tend to pander to her whims so go along with it (she is very spoilt).  As she is fairly convinced she is a person not a dog (hand reared, fussed over and petted, never told off as too tiny,  etc, etc) it seemed just part of her oddities.  But now we have Pipsqueak (nephew's pug) who will  always go for a pink toy first, if offered a preference - does not impress nephew too much as he says it is further evidence that Pipsqueak is gay :)