Necropsy photo's **GRAPHIC** Marek's disease, for info

[coach723]

This is informational for those that may have never dealt with this.
I have Marek's in my flock, most of my symptomatic birds have had occular symptoms, I have not had a bird with the common paralysis.
This bird was acting normally until 4 days ago, illustration of how well they can hide disease. No occular symptoms in this bird, no paralysis.
Found her standing with eyes closed, and a doughy crop. When I picked her up she was very thin. She was wormed in mid March and I did not note any issues then.
Treated to try to get the crop moving. Nothing was passing through her, even fluids, she was bringing everything back up even when not being handled. One small abnormal dropping in 48 hours, she was severely dehydrated and I could not get fluids in her. So I culled and opened her up. I did not send off for necropsy since I already know I have Marek's. This is what Marek's can do to a bird. Sorry for some pics that are blurry, was doing this rather quickly. As you can see she had tumors everywhere, liver wasn't too bad, but did have tumors, heart and lungs likewise, but everywhere else was affected. Gizzard was huge and crammed full (you can see it in the first picture), lower digestion had just stopped, her intestines were very impacted by tumors.

 

[samanthaoverton]

Thank you for sharing. That way others can know what to look for. I'm sorry your flock is going through this.

 

[Tankueray]

I can only speak to my flock,

No problem, that's why I asked all the questions, because there just isn't enough real, small flock data out there.

The visceral ones have been much faster to die, at least once they are sick enough that I know, and I'm not sure til I open them up.

In adult flocks that carry it without a lot of morbidity, the sudden sickness and unexplained death thing is pretty common and sometimes the only indicator.

For now I'm sticking with it and trying to make it work and breed for resistance. Won't know how that goes for a long time, I'm afraid. Have some growing out right now (my own hatch), and am watching closely to see when/if any show any symptoms.

That's really all you can do. Usually where I've seen the tell-tale signs is when they're reaching sexual maturity; I've never seen chicks with paralysis like in the literature, nor anything other than unexplained death or stunted growth in the under 16 weeks crowd. When I'm talking to flock keepers around here and they mention symptoms in birds that are about to go into lay for the first or second time, or newly minted cockerels up to one year, that's where the most likely "traditional" symptoms show up. That may be where the problem lies too, that mature adults are more often visceral and the young are more likely to present with symptoms. Like I said I've never seen ocular, but unfortunately I've never seen one presenting with symptoms recover either, and if they're being cared for and fed, it can take months for the disease to finally win. It's heartbreaking sometimes.

I haven't gotten any vaccinated birds as I have concerns about the leakiness of the vaccine, I'd rather deal with the devil I know. At least for now.

So that was the reason for one of my other questions, whether you knew if any of the parent lineage had been vaccinated. My curiosity was whether you actually had some resistance already and that's why only ocular and visceral.

Long, boring vaccine explanation ahead. (Click the button to read.)

Spoiler

Let's see if I can remember this....

There are three serotypes of the virus used in the vaccines on the market, MDV-1 (makes tumors), MDV-2 (doesn't make tumors), and MDV-3 (Turkey Herpesvirus, doesn't make tumors, similar, but not deadly to chickens). This gets kind of confusing because they denote the vaccines and the virus serotypes the same.

MDV-3 was the first vaccine (technically that's not true), based on a Turkey Herpesvirus (HVT), not Marek's. (Like the initial discovery that cowpox infection could protect against smallpox.) This is the one that you or I could order from most suppliers and keep in the fridge. (I actually do use this one.) It's not as effective as the others, and that's why it's not as widely used by the industry anymore. It's pretty ineffective against very virulent (vv and vv+) strains.

MDV-2 was the first one based on CVI988 (which is an MDV-1 strain that didn't present with tumors). It doesn't get used much because it's also not very good against vv/vv+ strains and the Rispens vaccine came along and was much more appealing to industry. It has to be maintained in liquid nitrogen.

MDV-1 - The one most often cited for leakage is the Rispens(CVI988) version based on serotype MDV-1, also the most common version currently used in industry and by commercial hatcheries (i.e., the gold standard), because it's good against vv and vv+ strains. It has to be maintained in liquid nitrogen.

BTW - They knew fully about the "leakage" when developing MDV-1 and MDV-2, more accurately, they tried a bunch of recipes and the only ones that would perform well enough also would still be infectious. Leakage kind of implies that it was an accident, but it was always a known challenge.

There's also evidence that MDV-2 and MDV-3 are basically negated by maternal antibodies (mom has fought the virus successfully, not sure if mom vaccinated with Rispens would do it too). But I'd read a newish study not long ago about giving a second vaccination of another serotype to help out. I believe that study had a group that was allowed to have the maternal antibodies dissipate prior to vaccination. I don't remember what that particular result was, but the overall consensus seemed to be that a late vaccination or a booster might be slightly more effective long-term and didn't seem to cause any harm, but they also didn't let the chickens live to maturity, so no real data on how well it worked. (In other words, "how do we decrease condemnation for tumors in 8-week old broilers to increase profits?")

So my current take on it is that using the HVT based vaccine will offer some protection by immune system training, but isn't actually Marek's and won't spread Marek's on its own. If an HVT vaccinated flock was challenged with Marek's could they spread it then? I believe they could, and it could be that by masking Marek's is how the vv strains came to be, but at the same time, that doesn't make sense from a biological perspective. Every organism's primary purpose is to reproduce, killing your host isn't very good for that, which is why the Herpesviruses are so hard to eradicate, they go dormant in the host, but some can spread without any indication of an active infection (and they generally aren't fatal). If anything, I would have expected that by suppressing the tumor inducing capacity of Marek's and using it so widely in industry, that's how the vaccines helped the disease to become ubiquitous and the vv/vv+ mutations were from some other selection pressure. It may be that the key to curing the disease is whatever it was that it was forced to overcome with those mutations.

As unfortunate as it is, I look forward to following your journey. Your commitment to working with Marek's is more valuable to small-scale and hobby poultry than a hundred research projects dedicated to industry. Thank you for doing it, and if ever you find yourself in need of some words of support or find yourself in Texas and in need of a cold beer, just let me know.

 

[coach723]

Thank you for all that, the vaccine info is very interesting. Some of my cockerels have started showing occular symptoms at about 6 months old. One of my young ones, they are 14 weeks now, has odd eyes, so am watching them, but they were odd early on, so may just be an anomaly. Not the shrinking, pinched pupil that I usually see, just kind of irregular with darker spots on the iris. Almost like coloboma, but not quite, and he's super skittish so haven't tortured him with trying to look closer yet. We'll see. So far the hens I've lost to visceral have been about 1 year old or older, so not seeing the point of lay losses that one might expect. At least not yet, we'll see how my pullets that are 14 weeks do. It's an odd virus with so many different possible manifestations. I lost two birds before I knew I had Marek's that I could not find an obvious cause for and no symptoms that made me think Marek's. So I wonder if they were. Did not find tumors in them, but found no other obvious cause either.

 

[casportpony]

This is one of my roo's, he's 6 years old.

Great pictures! you should enter @All4Eggz's contest!
Eye-Deal Poultry Eye Photo Contest

 

[Gizabelle]

Thank you for sharing your pictures and experience.
I have Marek's in my flock as well (confirmed by state lab). I lost another hen shortly after receiving the report and considered opening her up to see for myself, but couldn't bring myself to do it.
I'm so sorry about your birds. Marek's is truly awful, but stick with your survivors long enough and you may find resistant birds. Of my 5 remaining hens, 2 have made it past the two year mark, so it looks (knock-on-wood) like these two at least wil be ok.
Best wishes to you.

 

[coach723]

This is one of my roo's, he's 6 years old.

 

[casportpony]

This is informational for those that may have never dealt with this.
I have Marek's in my flock, most of my symptomatic birds have had occular symptoms, I have not had a bird with the common paralysis.
This bird was acting normally until 4 days ago, illustration of how well they can hide disease. No occular symptoms in this bird, no paralysis.
Found her standing with eyes closed, and a doughy crop. When I picked her up she was very thin. She was wormed in mid March and I did not note any issues then.
Treated to try to get the crop moving. Nothing was passing through her, even fluids, she was bringing everything back up even when not being handled. One small abnormal dropping in 48 hours, she was severely dehydrated and I could not get fluids in her. So I culled and opened her up. I did not send off for necropsy since I already know I have Marek's. This is what Marek's can do to a bird. Sorry for some pics that are blurry, was doing this rather quickly. As you can see she had tumors everywhere, liver wasn't too bad, but did have tumors, heart and lungs likewise, but everywhere else was affected. Gizzard was huge and crammed full (you can see it in the first picture), lower digestion had just stopped, her intestines were very impacted by tumors.

So sorry for your loss, but thanks for sharing.

 

[Tankueray]

Wow, thank you for the eye photos! Definitely not the floating gray eyeball that seems to be the most common picture out there. The distinction I was always told was that the pupil/iris was no longer round, and both eyes are different, which is quite clear in your roo. The hen looks more round and I'm with you, I'd be hesitant to call it if there wasn't already a diagnosis. The top eye looks not round, the bottom one looks pretty normal, except for the eclipse looking ring, but I might write that off as age too.

I had a pullet at one point that looked like she had kermit the frog eyes, I think there's a pic somewhere in one of my threads. The pupil was very dark from extra melanotic genes making it look that way, but the opening to the iris was still round and still reacted to light as it should (both the same). Disease can destroy color (as in the grey eye), but I've never seen it add it and the eye still be fully functional, so I hope I'm in the clear, but now I'm a bit freaked out and going to look at everyone's eyes tonight.

 

[Saaniya]

This is informational for those that may have never dealt with this.
I have Marek's in my flock, most of my symptomatic birds have had occular symptoms, I have not had a bird with the common paralysis.
This bird was acting normally until 4 days ago, illustration of how well they can hide disease. No occular symptoms in this bird, no paralysis.
Found her standing with eyes closed, and a doughy crop. When I picked her up she was very thin. She was wormed in mid March and I did not note any issues then.
Treated to try to get the crop moving. Nothing was passing through her, even fluids, she was bringing everything back up even when not being handled. One small abnormal dropping in 48 hours, she was severely dehydrated and I could not get fluids in her. So I culled and opened her up. I did not send off for necropsy since I already know I have Marek's. This is what Marek's can do to a bird. Sorry for some pics that are blurry, was doing this rather quickly. As you can see she had tumors everywhere, liver wasn't too bad, but did have tumors, heart and lungs likewise, but everywhere else was affected. Gizzard was huge and crammed full (you can see it in the first picture), lower digestion had just stopped, her intestines were very impacted by tumors.
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I lost one of my boy in October he also had a slow crop issue what happened is that on a hot day he ate food without having water first which locked his system and lead him.towards death I tried Almost everything he seems to be improve in middle but went downhill and died in melena