Two 8-9wk old chicks dead 6wks apart - Mereks?

[Flannery Eau]

Hi Everyone! I am new to backyard chickens (both the website and the birds) this spring. My boyfriend helped me build a new coop with a large run, and the chickens are able to free range (with 2 dogs) in my well covered backyard in St Louis City. Currently, the flock is 6, but we have lost two to a short but deadly illness that we suspect is Mereks.

We got four month-old chicks first (still not sure if they had been vaccinated against Mereks or not) - 2 Barred Rocks and 2 Australorps. They did great and we had just moved them into the coop when the largest and robust of the four (Rosalind, one of the Australorps) started limping. We thought maybe she had banged it jumping down from the roost, but there was no redness, swelling, tenderness, or inflammation. She became increasingly lame, and two days later was barely able to walk. I brought her inside, spent a day with her on my desk (she basically slept the whole time, but did try to both drink and eat), and then found her later the next day dead.

To replace her, we bought two two-week old chicks, one Ameraucauna (Persephone), and one Rhode Island Red (Georgene), from the local feed store. The people at the store assured us that both were vaccinated against Mereks and had come from hatcheries. We kept them in the basement for a week or two, and then put them outside in a side run separate from the others, and then in the big girl's run, but separated by some chicken wire. We then took the separator down, but the two groups of chickens essentially functioned separately from each other. These two did great, were essentially inseparable, and were starting to go up and roost with the big girls, when I noticed the Ameraucauna was less balanced when I held her and looked a little clumsy when she was walking around the run. She then became unable to jump up on the top of the chicken run (about 2 feet up) even when Georgene was up there. One morning, I found her in a corner in the back of the run unable to move except by a lot of flapping and flailing of wings. This girl was a real fighter - I couldn't remove her from the yard because Georgene would put up such a fuss, and she herself fought so much when I tried to put her in a box alone, I decided to separate her in the yard by a fence but still put her in view of Georgene, who stayed by her all day long and left only in the evenings to roost. It only got worse - over about two days, she became increasingly paralyzed, and soon her head could only move in spasms. She had the characteristic Mereks posture - one foot way in front, and the other retracted behind, and would chirp and try to eat up until the end. She died yesterday and we buried her next to Rosalind under a redbud tree. Both of them died at almost the exactly the same age (8-9 weeks), but they are 6-7 wks apart in age.

To replace her, we bought two more chickens - Margaret (a buff orpington), and Henrietta (a new hampshire red). They are the same age as Georgene and have helped her deal with her loss. Now we have two groups of chickens - the older ones and the younger ones, and they still have little to do with each other except when it is roosting time.

I called the feed store and they said that such paralysis was probably a vitamin deficiency and that if it was Mereks, the whole flock would have been wiped out. She also said that if it was Mereks, they would have cutaneous lesions. It doesn't make sense at all. First of all, there are a number of types of Mereks, only one of which is cutaneous, and secondly, all of these chicks (or at least the new ones) should have been vaccinated against the virus. Also, looking at all the common vitamin deficiencies of chickens (thiamine, phosphorous, vitamin c, etc), none of the symptoms match. This leaves me with a few questions that I would love if people could answer!

1. What are the chances that this actually was Mereks disease? Considering that both chicks were probably vaccinated - is this a case of an illness because of the vaccination, or a faulty vaccination, or maybe I just happened to get two chicks that missed the vaccination? What percentage of vaccinated chicks acquire the disease through vaccination? Their early deaths indicate that they came to me with the disease, and so I am confused about the effectiveness of vaccination and what it means for my other chickens.

2. Are there any other diseases that could cause these symptoms?

3. If it was Mereks, what does that mean for the rest of my flock? If they are vaccinated, are they carrying the disease but simply won't manifest it? Do carriers have any symptoms (like lower egg production)?

Any thoughts would be helpful, and thanks for reading!

 

[Kedreeva]

Well in answer to your second question: avian botulism can also cause paralysis like what you are describing. If there's bad feed or those chickens got into something moldy, that could be a problem. If they managed to gobble up something poisonous, that could be the problem as well.

As for checking what it was, if it happens again there are sometimes places you can take the body for autopsy that will do it for little or no cost. The name of said places escapes me at the moment. But an autopsy would most likely be able to confirm what is going on with your birds.

 

[MotherJean]

I believe that Mareks and Newcastle Disease are the big two for causing paralysis in chickens. And, as you suspected, that person at the feed store gave you bad information. Mareks doesn't always show skin eruptions and when they do it can be so mild (like goose bumps) that most people wouldn't recognize it as a symptom at all.

A Mareks infected bird with visceral tumors or brain lesions will (on average) begin to show symptoms about 4 weeks after infection (it takes time for the tumors and lesions to grow). So that sort of fits with your circumstances.

Here's a likely explanation - your birds were never vaccinated. I say that because it's not usual for chicks sold to feed stores to have been vaccinated for Mareks at the hatchery since it normally means an extra cost tacked on to the cost of the chicks. Also, there are some potential buyers (i.e. the "pure organic" crowd) that do not want chicks that have received vaccines. As you have already discovered, feed store personnel are notorious for giving out bad info. When I bought a group of 6 chicks from my local feed store in March, I asked the clerk, "Have these chicks been vaccinated?" (I failed to specify Mareks) The clerk said, "Absolutely!" And, she gave me a copy of the hatchery's NPIP form for that lot of chicks. No where on that form did it say that they had been vaccinated for Mareks, so I called the hatchery directly to find out. The hatchery representative told me that they only vaccinate their breeding stock for Pullorum Typhoid and that Mareks vaccines are given to chicks only when ordered and paid for. I called the feed store and told the clerk what I had found out from the hatchery. Her response? "Huh. I thought they had been vaccinated. My bad."

To answer your questions, specifically....vitamin deficiency can cause Mareks-like paralysis, but it most often fatal only in very young chicks (say, within the first four weeks). Newcastle disease can also present neurological symptoms, but the virulent strains of that disease are rare in the U.S. What's the chance that your birds are infected with Mareks? If I were in your shoes, I'd assume that all are infected and act accordingly. I know that Dr. Peter Brown of First State Vet Supply has advised a good many people on flock management and vaccination in the wake of a Mareks outbreak. I suggest you contact him through his website.