Ocular Mareks? (With pics)

[FeatherCrest]

Today, I noticed that one of the eyes of my rooster (4yo) changed colour. He usually has feathers almost covering his eyes, so I am not sure how long this has been, but max 3 months (last time I gave him a trim). He appears happy and healthy.

Are there any other possible causes than ocular Mareks? Our chickens are vaccinated, but one year ago we lost one hen to visceral mareks, so isn't it odd that we alsof have a different strain in the flock?

First pic: new colour
Second pic: original

 

[Kiki]

It's actually not too odd to have a different type of Marek's.
When you lost the last bird did you have a necropsy performed?

 

[FeatherCrest]

It's actually not too odd to have a different type of Marek's.
When you lost the last bird did you have a necropsy performed?

Not a necropsy, but the vet did a blood test which showed it was most likely mareks.

 

[coach723]

I also have Marek's in my flock. I have had some birds that only showed ocular symptoms, some others have only had the visceral form and it wasn't known for sure what it was until necropsy. I've had birds with ocular symptoms live for a couple of years and then pass from visceral tumors. It can vary a lot from bird to bird. In my flock I've never (yet) seen the typical forward/back legs or paralysis. It looks to me that it's very likely that it's ocular Marek's in your bird, based on what I've seen in my birds. When I see eye changes like that, with the grayish ring around the pupil, that's generally what it is. None of my birds has developed the completely gray iris that is often shown in pictures though. I see color changes in the iris, often the gray ring, irregularly shaped pupils and the pupil slowly shrinks til it looks like a tiny pin hole on those that live long enough. Both eyes are usually affected eventually, though they will not look the same. I recently lost the roo pictured below, this was taken awhile ago, but you can see the gray ring around the pupil and that both eyes have it but one is much worse. And the iris's are paler than they were, but not the total gray. The biggest thing I've learned about Marek's is that it is very often not exactly like the literature describes it, the symptoms are much more varied in reality, two birds may not look the same or have exactly the same symptoms. Below his pictures is one of my hens that I believe has it also, her eyes look different than his, but as you can see, are paler and the pupil is very misshapen.
I have seen progression to blindness in as little as a year, many take longer than that, at least how it's been here. Both birds pictured below have been symptomatic (ocular) for two years. The roo suddenly started losing weight and getting weak, and died from visceral tumors. The hen is still here.

 

[FeatherCrest]

I also have Marek's in my flock. I have had some birds that only showed ocular symptoms, some others have only had the visceral form and it wasn't known for sure what it was until necropsy. I've had birds with ocular symptoms live for a couple of years and then pass from visceral tumors. It can vary a lot from bird to bird. In my flock I've never (yet) seen the typical forward/back legs or paralysis. It looks to me that it's very likely that it's ocular Marek's in your bird, based on what I've seen in my birds. When I see eye changes like that, with the grayish ring around the pupil, that's generally what it is. None of my birds has developed the completely gray iris that is often shown in pictures though. I see color changes in the iris, often the gray ring, irregularly shaped pupils and the pupil slowly shrinks til it looks like a tiny pin hole on those that live long enough. Both eyes are usually affected eventually, though they will not look the same. I recently lost the roo pictured below, this was taken awhile ago, but you can see the gray ring around the pupil and that both eyes have it but one is much worse. And the iris's are paler than they were, but not the total gray. The biggest thing I've learned about Marek's is that it is very often not exactly like the literature describes it, the symptoms are much more varied in reality, two birds may not look the same or have exactly the same symptoms. Below his pictures is one of my hens that I believe has it also, her eyes look different than his, but as you can see, are paler and the pupil is very misshapen.
I have seen progression to blindness in as little as a year, many take longer than that, at least how it's been here. Both birds pictured below have been symptomatic (ocular) for two years. The roo suddenly started losing weight and getting weak, and died from visceral tumors. The hen is still here.
View attachment 3555553
View attachment 3555554
View attachment 3555559

Thanks for this, very helpful! (Although I don't like reading that ocular mareks does not mean they will not get the tumors - I was really hoping blindness was the worst that would happen). I recognize what you said about the symptoms not being exactly as described in the literature. Makes things even more difficult. I hope your hen stays around for a long time!

 

[Bobsfarm]

Thank you for this thread

My 3yo partridge star developed a pinpoint pupil a few weeks back (I'd never heard of occular mareks before that or any cause to think of mareks as I'd not knowingly had it in my flock) We did lose 1 of our old girls suddenly leaving 1 alone so we did a hasty covid purchase of 2 partridge stars, copper Maran and a leg bar from a reputable breeder.

Lost 2 of the flock early on but I suspected that they might have been too young and quite submissive and struggling with flockdown. They just lost condition and seemed to give up, the other 2 were fighting fit.

We got rescue hens in March this yr, quarantined them for 8 weeks. Then our old partridge star developed this pinpoint ppupils.

Her other pupil is now shrinking and today she was a bit puffed up and had a brief wing droop.... still flew onto the gate tho

Is it inevitable all will develop mareks? Even the ex Batts?

 

[coach723]

If it's Marek's then all of them have been exposed. Not every bird will necessarily develop symptoms or die. It can be very variable depending on many factors, the strain they have, individual immune systems, some breeds are more susceptible than others. With Marek's it's kind of a waiting game. If you have only a predominantly ocular strain then your losses may be less and they may live longer. The visceral form causes tumors in organs and can be sneaky and seem like a sudden death or sudden illness, and you may not know until necropsy, for sure. If you lose one that you suspect is Marek's it's a good idea to have a necropsy done with labs to positively identify it. Then there is no question. There is also a test that can be done on a live bird with a blood sample, if you are interested in doing that this is one source I know of:
https://www.vetdna.com/application/forms/aviansubmittalform.pdf
There are some things that can mimic Marek's symptoms. I have never seen the cutaneous form or the leg paralysis in my flock, only ocular symptoms and visceral tumors.
This is a good article, my journey has been similar, I think no two stories will be exactly the same:
https://www.backyardchickens.com/ar...-i-learned-to-deal-with-mareks-disease.76944/
Another useful article:
https://www.backyardchickens.com/articles/the-great-big-giant-mareks-disease-faq.66077/
And a long thread in which you may find some nuggets of usefulness:
https://www.backyardchickens.com/th...ding-for-resistance-to-mareks-disease.894589/