One brown and one blue eye - only in flash photos
Posted 21 August 2007 - 09:36 PM
Posted 22 August 2007 - 06:50 AM
I had a blue-eyed dog CERF'd once and they told me it was normal for blue eyes to reflect very RED off the back of the retina, and normal brown eyes I forget what they said, but my dogs all reflect an uncolorful white/yellow in most photos...
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Posted 22 August 2007 - 07:50 AM
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Posted 22 August 2007 - 10:00 AM
When you photograph a dog or cat with a flash, you will see a reflection
of color from the tapetum lucidum. You can also see this effect when
your headlights shine into an animal's eye. The tapetum lucidum (or "bright
carpet") is a layer of cells behind the rod and cone layer of the retina.
These reflective cells serve to intensify light in nocturnal situations.
This layer acts as a mirror, reflecting light back to the rods and cones.
In dogs this layer is present in one third of the back of the eye. As the
dog matures, the color of the tapetum changes from slate gray to violet to
red-orange at about 4 months of age. Some dogs, like huskys and collies
with blue irises (subalbinotic) lack a tapetum lucidum.
Rick Huneke, D.V.M./M.P.H. Faculty, Division of Comparative Medicine, Washington University School of Medicine
Posted 22 August 2007 - 10:22 AM
I asked my husband the photography geek if he had any idean and he was clueless too.
My old dog, Lily, when her eyes reflect in the porch light at night, are two different colours, but I know she has some cataracts in the "different" coloured eye which she was supposed to have operated on but now we've got the cancer diagnosis and she's healing so slowly I am reluctant to do it.
Posted 22 August 2007 - 12:20 PM
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Posted 22 August 2007 - 02:59 PM
Humans exhibit "red-eye" in flash photos because we do not have a tapetum layer behind our retinas, as dogs do, which enhances their night vision. Normally, a dog's tapetum (regardless of iris eye color) will reflect green or blue or yellowish-silver. In blue-eyed dogs, particularly in ones with merle body coloring, I have read that yes, as was mentioned above, their tapetums often can be less developed than usual, thus allowing the retinal blood vessels to be readily apparent and to reflect red in flash photos, as in humans--but that phenomenon in blue-eyed dogs is considered a normal variant.
In your BROWN-eyed dog, however, one would not expect the tapetum to be depigmented. Thus, if you have taken several flash photos of your dog, as you mentioned, and this red/blue eye reflection occurs 100% of the time, I would say that the eye reflecting blue in flash photos is normal, but that the one eye reflecting red in your flash photos would almost certainly seem to indicate tapetal hypoplasia (less developed than normal in the tapetum), as in blue-eyed dogs. I believe that this alone does not indicate an eye or vision problem, per se--perhaps your dog will only see a little less well at night in the affected eye.
You mentioned you were concerned about Collie Eye Anomaly, but this cannot be diagnosed from a flash photo. Essentially, the color of the reflection in a flash photo and possible tapetal hypoplasia have nothing to do with CEA, and do not indicate its presence or its absence, as far as I know. What may be confusing is that chorioretinal (not tapetal) hypoplasia is the pathognomonic (essential) finding in CEA, meaning that the choroid, or vascular (blood vessel) structural layer behind the retina is less developed than usual (as opposed to the tapetum), and this is not something that you could diagnose in a flash photo. If this were CEA, there would also be a number of other associated findings, and I believe that CEA is always in BOTH eyes, though the defects may not necessarily be symmetric. Again, I do not believe that tapetal hypoplasia is linked to chorioretinal hypoplasia, but that is something that a vet would need to confirm for you, as the only real way to ascertain any definitive diagnosis would be to have your dog's eyes examined by a board-certified veterinary ophthalmologist. If it were my dog, I would take him, just so I could be sure that there was nothing wrong! You say your guy is four months old, so it may be a good idea anyway to get a baseline eye examination on him before he gets much older--I believe CEA is present at birth and does not progress (unlike like PRA), although some CEA-positive dogs will exhibit a "go-normal" phenomenon as they get older, in which the initial CEA chorioretinal hypoplasia is masked by late development of the tapetum, making it impossible to differentiate these dogs from CEA-clear dogs, which is why dogs are best examined for CEA at <8 weeks of age.
I really hope that helps! You certainly made a very astute and interesting observation about your dog's eyes.
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