This is my explanation as to why some Siamese cats are cross-eyed or at least it is possibly part of the reason. Crossed-eyes are fairly common amongst Siamese cats. You’ll also see it random bred cats too but some people treat the condition as a normal part of the anatomy of this cat breed. That is incorrect because breeders are breeding it out. You’ll probably see it much more in Thailand together with the Siamese kinked tail that has been bred out in the West. At one stage the kinked tail was as common as the cross-eyed gaze for this famous cat breed.
The condition is inherited. It is a genetically based condition. Robinson’s Genetics¹ say that the albinism gene has “other effects” on the Siamese cat. What they mean is; effects other than the coat pattern and color with which we are so familiar.
They go on to state that the albinism allele² causes a disruption in the visual pathway “preventing these cats from having full binocular vision”. I disagree that the Siamese cat does not have full binocular vision, by the way. They further state that Siamese cats “neurologically compensate” for this anatomical anomaly. In my view, we see the effects of the compensation in the crossed-eyes, also called a squint. The technical term for misaligned eyes is “strabismus”. The cross-eyed cat has horizontal strabismus as far as I am aware.
A study³ concluded that the brain of one of the extremely popular white tigers that we see in zoos (and which are sadly highly inbred) showed an abnormality of the visual pathway similar to the “abnormalities that are associated with albinism in many other mammals”. The authors state that:
There is a close relationship between the reduced pigment formation, the pathway abnormality, and strabismus.
The image on this page explains more behind my conclusions that reduced pigment formation (of melanin) due to the presence of the albinism gene causes the misrouting of the optic nerve.
I can’t, at the moment, explain why only some Siamese cats have a squint. There is perhaps more going on with respect to genetics than stated, I suspect. Or it may be that some cats just compensate without showing a squint and some cats just grow out of it (correct it as stated).
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- Robinson’s Genetics for Cat Breeders and Veterinarians page 169. The quote in the image is from this book too.
- Allele: one of two or more versions of a gene.
- Ref: Genetic Abnormality of the Visual Pathways in a “White” Tiger