How common is Coloboma in chickens?

[ambe0487]

One of my original girls as always had a strange eye and as I’ve hatched over the last 3 years I’ve noticed it is coming more and more often.

Here are a few examples from my flock

 

[coach723]

I know absolutely nothing about this, a new one for me, but found this info, I'm sure there is more. It appears to be genetic and more prevalent in females than males from my quick read.

https://www.ncbi.nlm.nih.gov/pubmed/15529996
https://academic.oup.com/jhered/article-abstract/61/3/95/793792?redirectedFrom=PDF
http://journals.plos.org/plosgenetics/article?id=10.1371/journal.pgen.1007246

 

[rebrascora]

Are you sure it isn't ocular Marek's?

 

[Eggcessive]

Coloboma is common in humans, birds, and other animals, and can be caused by a genetic mutation. A misshapen pupil can also be a sign of ocular mareks. Is the color of the iris the same as the other side? Do any of these chickens have a grey eye?

 

[Nambroth]

I am not sure how common coloboma is in chickens, but it does strike me as strange that you are experiencing it in so many (?) of your birds. Are the ones that have it related? If so then it might well be genetic. If they are unrelated, is there the possibility that you have a strain of Marek's that presents most frequently as ocular Marek's? Have you had any other signs of illness or deaths in your flock over the last three years that align with Marek's symptoms?

Grey eyes or blindness in the eye can be a sign of Ocular Marek's, but itsn't necessarily always present. My Faverolles hen started presenting ocular Marek's at 4.5 years old and she never developed the grey eye, just the "keyhole" or drippng shape to her pupil.

It's a bit hard to tell from your photos but sometimes chickens do have mottled looking irises, as well. Is the pupil shape actually changing, or is it just dark pigmentation on the iris? It may require someone to help you hold the bird and a strong light to look into their eyes to see if you can tell. Coloboma is a malformation.

 

[ambe0487]

Sorry, long day here. Thanks for all your replies.

The gal in the first photo is from when I first put them out in their coop at 8 weeks. I hatched those birds inside (shipped eggs) and they had no exposure to other birds during that time. None of the others from that hatch have this issue.

As for the rest, the fibro girl with white feathers is not related to the gal in the first photo but is the aunt of all the rest of the birds above.

None of the birds have grey eyes and all birds have same color for both eyes.

I hate to even write this for fear of jinxing myself but I have had zero losses or major illnesses in my flock since I hatch my originals 3 1/2 years ago.

All of them seem to have had it from a young age most were at least 6 weeks of age when I’ve noticed.

If it is Ocular Mareks, should I be seeing it in the rest of my flock or in he other birds my broody’s have hatched? I’ve been hatching under my broody’s the last 2 years pretty consistently and I have 3 other flocks that typically take some of my hatchlings. I’d have to think someone would be showing signs as well from their flocks if it were contagious as I’ve read.

@Rebascora, @Eggcessive @Nambroth

 

[Eggcessive]

Here is a study about coloboma being hereditary in a flock:
https://www.ncbi.nlm.nih.gov/pubmed/15529996

Since it doesn’t seem to be affecting them or causing any illness or symptoms, I probably would not worry about it.

 

[drumstick diva]

agree. This is the first time I have heard about coloboma. I will have to check that thread out.

 

[ambe0487]

Sorry I forgot to add that there doesn’t seem to be any vision propblems in any of the birds. The one boy (blue with large comb) has more of what I would call a stargazer pattern in both of his eyes so maybe it’s just his coloration. I don’t see any keyholes on his eyes.

 

[ambe0487]

I talked to a gal that has 4 of my birds from this same hatch and 2 have the weird spots or misshapen eye as well. One boy and one girl. I checked through the rest of my flock and no other have this. So with exception of my older girl, all the rest have been from this same gene pool exclusively who have this.