1 Yr old Hen: Sudden blindness in one eye

[Tower]

We have an approximatively 1 year old hen who suddenly (within 24 to 48 hours) developed a blindness in one eye. To test this we brought her into a dark room and used a flash light, her left side the pupil contracts normally, her right does not contract and shows no reaction to the light. She is craning her neck to look using her good eye, also she does not appear to be eating, she's lethargic, and from what we can tell is not defecating. We examined her vent and that appears to be clean. We first discovered her condition when observing her attempting to get out of the coop and was having difficulty walking around. She appeared to have a injured leg however she has no reaction when handling her physically and no apparent injury or pain. She has lost most of the feathers around her neck as have a few other of our hens, however they are not exhibiting this behavior.

Their environment is an enclosed run around a 11 x 37 ft rectangle (enclosed as well from above). Little vegetation is in their run (they devour anything that comes up). There are 14 hens sharing this area with a large coop. They free range and are fed an organic layer feed, scratch and other organic vegetables from our meals. They also receive twice weekly yogurt for additional protein. Weather lately has been fairly damp as we live in the Pacific Northwest.

We have brought her inside and separated her from the other chickens till we can determine the cause, any advice would be most helpful. I have also included some pictures to illustrate her feather loss:

 

[matthewschickens]

Mine had something like that happen to her: https://www.backyardchickens.com/forum/viewtopic.php?id=287621

Hope that helps and Welcome!!

Matthew

 

[Sir Birdaholic]

I think we may have 2 different issues. The feather loss may be due to mites, & as for the blind eye & limping, you may want to read up on Mereks disease. Just my opinion, I'm not a vet. Good luck.

 

[Tower]

Ocular Mereks was something we researched, however we were not sure if 1 year olds were too old for this type of Mereks in addition her eyes show no visible problems (no grey or cloudy coloration).

Secondly she is part of our second generation which we rescued as adults from an over populated farm (we took a total of nine hens). Our first generation were hatchery birds and they are vaccinated against Mereks. We have eight three week old hatchery chicks inside in our brooder which were also vaccinated against Mareks. We are concerned about the 2nd generation, since we have had another bird that has had various health issues (eye infection, and prolapsed vent ((all of which have been treated and that particular bird appears to be fine). We are concerned about adding our third generation into this flock due to problems that are appearing with the 2nd generation. Should we consider culling all the 2nd generation birds to ensure the flocks health?

Mites appear to not be the issue as we treated them a number of times with diatomaceous earth and out of the 14 birds we have only four that exhibit loss of feathers on their necks only (all of which are 2nd gen).

Thanks again your help is very much appreciated.

 

[Tower]

Bump

 

[MotherJean]

There's some very good information on Marek's on this thread: https://www.backyardchickens.com/forum/viewtopic.php?id=349905

Specifically, go to post #8 where you'll see photos of Marek's eyes. One form creates the gray iris. Another looks somewhat normal except the pupil is generally dilated and uneven. Both are blind. Also, while it is true that Marek's generally afflicts birds between 5 and 25 weeks, the PoultryOne article notes that MD "can appear even later if the bird had 'latent' MD and is substantially stressed. However, if the bird is a few years old, I would suspect a similar disease called Lymphoid Leukosis (which does pass to the egg). Both diseases will produce internal lesions (or tumors), detectable upon postmortem examination, but LL does not produce paralysis."

You ask about culling the 2nd generation. Personally, I would cull any birds that are clearly sick or unthrifty. So long as you exercise some precautions when bringing in subsequent additions to your flock (vaccinations and isolation from the 2nd generation birds until new birds are at least 5 months old), it may not be necessary to cull the entire 2nd generation because of suspected MD. Even with the 2nd gen birds gone, Marek's can remain in the environment and infectious for over a year. It's not easy closing that door once it's been opened.

Whether you cull or you don't, I strongly suggest that you practice good bio-security when bringing in any new birds to your flock. If you'd like more info on best practices of bio-security, you can find it at the USDA website here: http://www.aphis.usda.gov/animal_health/birdbiosecurity/