Marek’s management

[Mixed flock enthusiast]

Recently had a definitive diagnosis of Marek’s from necropsy at state lab, trying to figure out what to do now. Note that: A) we are attached to these chickens and want to keep as many as possible, B) we would still like to do some breeding in the future, but these will be replacement birds for us, not for sale. There are three groups of chickens, 1) 7 month old barnyard mix, five pullets and one cockerel. All vaccinated as day old chicks with the usual cell free vaccine. 2) 8 five month old pure breeds from local breeder, not vaccinated. 3) four 2 month old chicks from same breeder, not vaccinated. We have most group 1 and 2 birds in a coop/run. None of these have shown disease yet. 50 feet away from this coop is a tractor that had a silkie and Frisian gull cockerel. We lost the gull to Marek’s 10 days ago, silkie still looks normal. Note that guineas constantly move between tractor and coop, and that I had two unvaccinated coop chickens out with the silkie two weeks ago. Therefore, I expect all coop birds have been exposed. The youngest, group 3 chicks are some distance from coop, separated by our house. There, we’ve lost 3 of 7 chicks, with Marek’s confirmed in the last. Three remaining birds look healthy, one I’m worried about but no obvious Marek’s yet.

Plan: euthanize any birds that show lameness or wasting. I’d like to get more vaccine and vaccinate/revaccinate groups 1/2. I realize this is probably ineffective, but before eventually combining groups, I’d like to be confident that all have been vaccinated or exposed since no one in the coop has been sick yet. I had planned to separate group 1 into their own pasture coop so I guess I’m still planning to do that. Two weeks after vaccination, I plan to put the silkie cockerel into a “bachelor pad” with black copper Marans cockerel from group 3. I had planned to integrate the rest of group 3 birds into main coop. Should I wait until they are full grown (6 months) at this point so they will have gotten the virus under control as much as possible first? Or should I vaccinate and wait two weeks then move them in?

Any thoughts appreciated!

 

[Rose Quartz]

I'm pretty sure they can only be vaccinated as day olds.

 

[Mixed flock enthusiast]

I'm pretty sure they can only be vaccinated as day olds.

There is very little recent information on the old HVT vaccine that is accessible to backyard flocks, but there is so indication that the newer Marek’s vaccines have better efficacy with revacination. At any rate, I’m not seeing that vaccinating late will cause problems, just that it’s unlikely to work. I realize vaccination of coop chickens is kind of a Hail Mary move, but I’m only seeing lack of effect as the down side, unless someone has other information?
https://www.researchgate.net/public...ckens_against_Marek's_Disease_-_A_Case_Report

 

[EggSighted4Life]

Good morning.

Sorry for your losses.

Vaccinated birds NOT welcome here...They can still catch MDV and JUST not display symptoms such as the tumors that cause the paralysis and STILL be shedding live virus among the whole flock. I rather dispatch any that display and let it cull itself out than helping it to perpetuate and live on happily UNdetected.

What is the "usual" cell free vaccine?

There has been a gene identified that does create resistance to MDV.. and I breed for resistance in my stock.

Revaccinating is a waste of time, money, and energy IMO.

Best thing you can do to control MDV after diagnosis... partly depends on your goals. Some people like @rebrascora works to minimize stressors and I'm sure she will share her other stuff. I personally dispatch immediately anyone limping with no sign of injury. And importantly... keep nutrition adequate and do NOT diminish nutrients with with empty calorie treats. Don't invite wild birds to your yard by hanging feeders. And don't bring in any birds from someone else's pasture.

I personally would do all my integration NOW... and think getting the virus "under control" is wishful thinking... BUT I am here to learn and to see what works for other people also.

The most accurate and well written information I have seen on the subject was written by one of our very own BYCer's. Experience is the mother of all teachers...
https://www.backyardchickens.com/articles/the-great-big-giant-mareks-disease-faq.66077/

I know it seems scary, hang in there!

 

[Wyorp Rock]

Plan: euthanize any birds that show lameness or wasting. I’d like to get more vaccine and vaccinate/revaccinate groups 1/2. I realize this is probably ineffective, but before eventually combining groups, I’d like to be confident that all have been vaccinated or exposed since no one in the coop has been sick yet. I had planned to separate group 1 into their own pasture coop so I guess I’m still planning to do that. Two weeks after vaccination, I plan to put the silkie cockerel into a “bachelor pad” with black copper Marans cockerel from group 3. I had planned to integrate the rest of group 3 birds into main coop. Should I wait until they are full grown (6 months) at this point so they will have gotten the virus under control as much as possible first? Or should I vaccinate and wait two weeks then move them in?

Any thoughts appreciated!

I think culling birds that show symptoms would be your best bet.
Vaccinate? That would be up to you after you do a lot of reading/research. Bird that are vaccinated may have less tumors, but they can still become infected with the virus. Many, many posts of vaccinated birds that still have paralysis, wasting and sometimes eye problems.
Here's a very good place to start with you research.
http://www.backyardchickens.com/a/the-great-big-giant-mareks-disease-faq

 

[Mixed flock enthusiast]

Good morning.

Sorry for your losses.

Vaccinated birds NOT welcome here...They can still catch MDV and JUST not display symptoms such as the tumors that cause the paralysis and STILL be shedding live virus among the whole flock. I rather dispatch any that display and let it cull itself out than helping it to perpetuate and live on happily UNdetected.

What is the "usual" cell free vaccine?

There has been a gene identified that does create resistance to MDV.. and I breed for resistance in my stock.

Revaccinating is a waste of time, money, and energy IMO.

Best thing you can do to control MDV after diagnosis... partly depends on your goals. Some people like @rebrascora works to minimize stressors and I'm sure she will share her other stuff. I personally dispatch immediately anyone limping with no sign of injury. And importantly... keep nutrition adequate and do NOT diminish nutrients with with empty calorie treats. Don't invite wild birds to your yard by hanging feeders. And don't bring in any birds from someone else's pasture.

I personally would do all my integration NOW... and think getting the virus "under control" is wishful thinking... BUT I am here to learn and to see what works for other people also.

The most accurate and well written information I have seen on the subject was written by one of our very own BYCer's. Experience is the mother of all teachers...
https://www.backyardchickens.com/articles/the-great-big-giant-mareks-disease-faq.66077/

I know it seems scary, hang in there!

Thanks for responding, interesting to read your perspective since I’m kicking myself for not insisting that we only acquire vaccinated chicks! I’ve read that FAQ, thanks for linking it. I’m a virus researcher (alphaherpesviruses in horses and monkeys, ironically) so I’ve also been reading as much of the scientific literature as I have time for. It’s so hard to apply the work done for large scale poultry industry to back yard flocks! The “regular vaccine” is the Herpesvirus Turkey, serotype 3, live virus in media without cells or cell-free. This is the one that you can order from Stromberg, ValleyVet, etc. It’s not the “gold standard”, cell-associated vaccine that is stored in liquid nitrogen.
http://m.thepoultrysite.com/news/37156

 

[rebrascora]

You are clearly much more knowledgeable than me as regards vaccines and how they work and I assume you are aware of the issues with the vaccine which is available to backyard flocks. If the vaccine was effective at preventing Marek's then I might be more enthusiastic about it, but since it is known to be "imperfect" or leaky, I am of the belief that it may be responsible for the more aggressive strains of Marek's which seem to be becoming increasingly common. I am of a similar opinion to @EggSighted4Life that I prefer to "know my enemy" than have spies in the camp. That said, I have one of the milder strains that have not perhaps had the opportunity to mutate, because I don't vaccinate and my flocks are finding their equilibrium with the disease as the years pass. I breed from survivors. I broody rear chicks within the Marek's flock. I actually support my Marek's birds as long as they are prepared to fight the disease and only euthanize once they lose interest in food. One of my broodies this year had an outbreak of Marek's in Jan/Feb and recovered. He chicks are 5 months old, so I am approaching the critical point for them to start exhibiting symptoms and keeping my fingers crossed. Her eggs were a new experiment this year as I purchased hatching eggs for the first time instead of hatching from my own flock to see how the new blood stock would cope.

I do not know what I would do in your situation, with you already having a mixture of vaccinated and unvaccinated and since you are still in the early stages of your diagnosis, you will not really know how aggressive or otherwise, the strain you have is. It takes time to get to know it and learn how best to manage what you have so all I can say is follow your gut instinct. I would disinfect the coops where you had symptomatic birds. The risk of infection is highest in the coop in my opinion, where the reservoir of infected material is highest and most easily made airborne and hence inhaled. Virkon S in one of the few disinfectants which is active against the virus and here in the UK can be purchased very cheaply is small sachet sizes that dissolve in a bucket of water for £2 a sachet. Because birds are only shedding the virus whilst they are symptomatic, it makes sense to have a coop clean after you have had an outbreak.

I have had some birds make some pretty miraculous recoveries even after extended periods of paralysis, sadly others are not so lucky. The virus does seem to settle down to a low level after the first year or so though without vaccination in my experience.

 

[Mixed flock enthusiast]

Thanks Rebra. I guess that my main question is going to be tough for anyone to answer. I don’t know if the first group of breeder chicks was already exposed to Marek’s or if they are just now getting exposed. We did lose 2/15 of those earlier chicks, no necropsy so could have been Marek’s. However, we’ve lost almost half of the new chicks, so I’m thinking that the first group may not have been exposed until recently, transferred from the new chicks. If that’s the case, then mixing the two chick groups could be bad, since the newer chicks would be expected to be shedding more since the infection is more recent. However, if it’s already worked through the older chicks, then combining should be fine. Housing is an issue; I’ll need to build if I need to keep newer chicks separate for four more months... I’m trying to get ahold of the breeder to ask her this, but she’s not returning my correspondence, and I’m not sure that she would really answer this question anyway, since it would mean admitting to the sale of chicks that she knew were exposed to Marek’s.

 

[rebrascora]

The act of uniting the two flocks of chicks will cause stress and that will probably trigger some that are carrying the virus to have an outbreak, so you may find an increase in incidence of symptoms after combining them but it may not necessarily be because they have been newly infected, by members or one flock or the other. Time scales can be quite telling in that respect. If you get symptomatic birds in the first couple of weeks of mixing the flocks then they were already infected and carrying the disease, if it is 3+ weeks after mixing them that you start to see sick birds then they were probably newly infected. That doesn't help you to decide what to do but just what to consider if you go for that option.

I think you have to find somewhere to draw the line between what is or is not practical (ie. building a new coop) and will it be enough to reduce the risk to the birds (even the act of moving them to a new coop will cause some stress). I have undoubtedly been taking risks by raising chicks within my Marek's flock and this year an even greater risk was in using purchased hatching eggs from another breeder.... There is the possibility that some will get the disease and possibly die but some (maybe all if I am lucky) will not. I have to take responsibility for that decision and see where it leads me and make choices next year based on what happens. It isn't easy, but you have to accept that there will be deaths and learn how to manage them to minimize it, but don't allow it to ruin or dominate your whole chicken keeping experience, otherwise what is the point.

 

[Mixed flock enthusiast]

The act of uniting the two flocks of chicks will cause stress and that will probably trigger some that are carrying the virus to have an outbreak, so you may find an increase in incidence of symptoms after combining them but it may not necessarily be because they have been newly infected, by members or one flock or the other. Time scales can be quite telling in that respect. If you get symptomatic birds in the first couple of weeks of mixing the flocks then they were already infected and carrying the disease, if it is 3+ weeks after mixing them that you start to see sick birds then they were probably newly infected. That doesn't help you to decide what to do but just what to consider if you go for that option.

I think you have to find somewhere to draw the line between what is or is not practical (ie. building a new coop) and will it be enough to reduce the risk to the birds (even the act of moving them to a new coop will cause some stress). I have undoubtedly been taking risks by raising chicks within my Marek's flock and this year an even greater risk was in using purchased hatching eggs from another breeder.... There is the possibility that some will get the disease and possibly die but some (maybe all if I am lucky) will not. I have to take responsibility for that decision and see where it leads me and make choices next year based on what happens. It isn't easy, but you have to accept that there will be deaths and learn how to manage them to minimize it, but don't allow it to ruin or dominate your whole chicken keeping experience, otherwise what is the point.

Yeah I am really struggling with the responsibility, especially because the coop birds look healthy and include my daughter’s beloved silkie and showgirl and my favorite cream legabars! I’m really afraid that we are going to lose them. I finally reached the breeder and that was not helpful. NPIP certified but doesn’t necropsy her dead birds and doesn’t seem very interested in hearing that we’ve lost half of what she sold us two months ago. I think that I’m going to build a small coop out front and ride things out for a bit. It’s possible that we are in the calm before the storm and our favorite 5 month chicks are about to start dying. I think I’m in the “above all, do no harm” frame of mind.