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What is Marek's Disease?

Marek’s disease is a very common disease that may affect your chickens. It spreads quickly through a flock, affecting young birds between the ages of 8 and 20 weeks of age. If you raise chickens, it is vital to understand the signs of this virulent disease so that you can take action against it. There is no cure, with prevention being the most important course of action to take. The disease occurs most commonly as the nervous form, with progressive paralysis in one or both limbs, and sometimes showing in the neck or wings as one of the main symptoms.

Marek’s disease is highly contagious amongst chicken flocks and is caused by the herpesvirus. There is no cure and it brings a high mortality rate.

Symptoms of Marek's Disease in Birds

  • Vision impairment, with a change in the eye colour showing a grey iris or irregular pupil 
  • Skin change in texture around the feather follicles, often appearing raised and bumpy 
  • Lameness and leg weakness without any visible signs of swelling or heat within the limb 
  • Partial or progressive paralysis of the limbs is a typical symptom of Marek’s disease 
  • The paralysis can also affect your chicken’s neck or wings causing your bird distress  
  • Loss of weight due to the inability to reach the water and their feed  
  • Difficulty in breathing 
  • Diarrhea 

Types

  

Nervous Form

 The most common type of Marek’s disease begins as a progressive paralysis of the neck or wings, and limbs, affecting the sciatic nerve (main leg nerve). If your bird has this type of MD it may seem uncoordinated on its feet. Paralysis takes over very quickly and blindness can occur.

Visceral Form

This presents as tumors within the internal organs of your bird such as ovaries, spleen, liver and heart. Symptoms include depression, paralysis, loss of weight, anemia (pale combs) and sometimes diarrhea. Your bird may die suddenly without any sign of the disease.

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Causes of Marek's Disease in Birds

  • Marek’s disease is caused by the herpesvirus or more specifically, it is a DNA virus 
  • This highly contagious disease (among your chickens) is spread by chicken dander (dust) through inhalation 
  • This condition increases the risk of other diseases as the immune system is compromised 
  • It can also spread rapidly through contact with other contaminated chickens in the flock 
  • Dander from other wild birds, the wind, human shoes can all spread the disease 
  • It can be spread through environmental factors such as an infected enclosure
  • MD can survive in the soil where chickens are kept for at least five months
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Diagnosis of Marek's Disease in Birds

If your notice any of the symptoms of Marek’s disease within your bird population you will need veterinary assistance to diagnosis this condition. On examination, the symptoms will be a major factor, and if any of your flock have died, a post mortem will confirm your veterinarian’s analysis. With post mortem findings, the enlargement of the nerves such as the sciatic nerve will be obvious, and changes within the internal organs may be visible. 

There is a vaccination (for commercial poultry but small doses are not yet available to the backyard bird keeper) against MD that is advisable for your birds; it is not a cure, it only helps your bird to build up a resistance to the disease. In other words, just because your bird is vaccinated it is no guarantee that it will not catch this disease. Marek’s disease is a common virus that occurs where there a flock of chickens being raised. It can spread rapidly in unvaccinated birds, so that they become infected. They can carry the virus for life and can shed the virus through the feather follicles which then spreads rapidly in the dust and fluff in the environment. One thing to note, it is not spread from the hen to the chick through the egg, and the meat and eggs from infected birds are perfectly safe to eat.

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Treatment of Marek's Disease in Birds

There is no cure or treatment for Marek’s disease. Those birds who are diseased should be removed from the others, and sadly humanely destroyed. Close monitoring of your remaining birds to see if they are infected is important. Although vaccinations are commonly used for those commercial poultry farmers, it is not available in small doses for the hobby poultry keeper. If you are buying new birds choose from a commercial source that has vaccinated its stock. Although it will not prevent your birds from getting this disease, it will make them more resistant to it.

Preventative measures are also important, such as ensuring chicks are separated and reared so that they don’t get the infected fluff and dust of older birds. A regular clean out of the shed or enclosure, and equipment such as feeding bowls is very important. Disinfecting these areas will help prevent MD. Superior quality feed and regular treatment from parasites is also good practice. By practicing good management, it will ensure your birds have the best chance to resist Marek’s disease. Consult your veterinarian regularly as to the annual care for members of your backyard flock.

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Recovery of Marek's Disease in Birds

There is no cure for this disease. There is only prevention and management of your birds. Because MD is spread via chicken dander and dust, maintaining good conditions within enclosures is important. Sterilising of the utensils, perches and even relocating the birds to another enclosure while you turn over and treat the soil (if you have a dirt floor) is a good routine to get into. MD is not contagious to humans thankfully. But care with new breeding stock or chicks from reputable breeders who vaccinate their birds is important. Because this disease is so contagious it can travel through your flock of birds leaving them decimated within weeks. Prevention is an essential part of bird rearing management.

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Marek's Disease Questions and Advice from Veterinary Professionals

Need pet health advice? Ask a vet

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Ask a Vet

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Milk and Oreo

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Bird

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6 Months

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Critical severity

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0 found helpful

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Critical severity

Has Symptoms

Leg Paralysis Won’T Eat Or Drink

We had 9 chickens about 6 months old. We went on vacation and my parents kept an eye on them. When we got home one chicken would not get up. My parents said she was acting weird for a few days. We brought her inside and it was as if her legs were paralyzed. She died that night. Two others we noticed could not hop up onto their roosting bars and one layed down at the back of the coop. The next day she hadn’t moved. Her legs are paralyzed and she won’t eat or drink. We separated these two chickens and the one has not been able to use her legs since Thursday. We are giving her water with electrolytes with a syringe. We don’t think she will make it. The other chicken is still able to walk and eats and drinks fine. She’s just moving slowly and not herself. Could this be Marek’s disease? Please help!

Sept. 16, 2018

Milk and Oreo's Owner

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Group of chickens

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Plymouth Rocks

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7 Months

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Moderate severity

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2 found helpful

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Moderate severity

Has Symptoms

Mareks

I have some Plymouth Rock one pullet died very suddenly another very unwell stumbling took her the vet did a necropsy came back not Mareks but a very rare tumour. Then 2 day's ago my rooster he was about 8 months ago started limping then could not walk. Went to the vet he was euthenized had a necropsy done by that vet he had tumours in his liver consistent with Mareks. I have 3 remaining pullets and 3 hens and one young rooster the brother of the one that died. Do you think I could lose the whole flock none are symptomatic. The other chickens it all happened over the last 6 weeks. Thanks Judy

Aug. 16, 2018

Group of chickens' Owner


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3320 Recommendations

It is possible that all may be lost over time, however you may want to think of culling and repopulation since you have a small number of chickens; you should discuss with your Veterinarian. Regards Dr Callum Turner DVM

Aug. 16, 2018

Thank you for advice regards Judy

Aug. 17, 2018

Group of chickens's Owner

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Philly

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Buff Orpington/Red Sussex

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1 Year

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Moderate severity

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0 found helpful

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Moderate severity

Has Symptoms

Bloody Vent, Eye Discoloration
Multiple Symptoms Above

I cannot tell what is wrong with my rooster, Philly, who I’ve hatched over a year ago. He has had several symptoms at different times. The first morning I had noticed he was bleeding from his vent and was often complaining. He did not poo much. The next days on I noticed that he looked pale and sick in the face, his eyes were irregularly shaped and discolored. His eyes were originally orange. I have been feeding him plain yogurt, corn, bread and fresh water. He was eating okay but he had lost a lot of weight. He stands around a lot like he is the most saddest chicken on Earth. He has not crowed in the past 2 weeks. I have 11 healthy chickens.(2 roosters; the rest are hens)I regularly clean out their coop refresh their water and give them plenty of food. I was not aware about Mareks disease at the time I hatched him so there was no prevention. This has been going on for a week.

Aug. 9, 2018

Philly's Owner

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3320 Recommendations

Apart from the ocular changes there is little else tying in with Marek’s Disease; however if you do suspect that Philly has Marek’s Disease you should visit an Avian Veterinarian to be on the safe side, but generally a definitive diagnosis can only be made at necropsy. Regards Dr Callum Turner DVM www.msdvetmanual.com/poultry/neoplasms/marek’s-disease-in-poultry

Aug. 10, 2018

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Tanner, sweetie

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Appenzeller

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5 Months

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Serious severity

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1 found helpful

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Serious severity

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Puffed Up Uncoordinated

I got some 3 month old chickens 2 months ago. after about 1 month 1 was acting ill, fluffed up feathers diarrhea. Her wings would droop the she was walking uncoordinated. She died in a day, then a cockel died. a few days later another became ill and I syringe fed her but she died after three days same fluffing up, not eating, uncoordinated. I thought they were okay and then a month later another became ill closing her eyes laying around puffed up uncoordinated and she died after two days. I have 5 left in that group. Do you think it is Marek's? I have other chickens but have kept them separated. Thank you.

Aug. 8, 2018

Tanner, sweetie's Owner


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3320 Recommendations

A diagnosis of Marek’s Disease is based on a necropsy examination of dead birds which would indicate characteristic lesions of infection including lymphoid tumours, enlarged nerves, bursa atrophy among other signs; ante-mortem symptoms are indicative but not conclusive. Regards Dr Callum Turner DVM www.msdvetmanual.com/poultry/neoplasms/marek’s-disease-in-poultry

Aug. 8, 2018

Thank you. If I have another loss I will get a necropsy.

Aug. 8, 2018

Tanner, sweetie's Owner

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Rooster

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Japanese Bantam

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6 Months

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Critical severity

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Critical severity

Has Symptoms

Lethargy
Paralysis
Lame

Hello, we had 6 point of lay bantam chickens until 3 weeks ago one got sick and died. Then 2 weeks later another one became lethargic and then paralyzed until within 5 days it also died, even with a lot of care and nursing. Now the rooster of the brood has become paralyzed and lying on his side. Comb and wattles are good color. Legs appear in good condition, yellow in color. Head movement good, alert. Eats and drinks well when food/water is right in front of him but otherwise immobilized. No signs of blood in poo. No signs of anything coming from beak/mouth. Is this likely to be Marek's disease? Is there anything that can be done to help recovery and prevent spread to other 3 birds left?

July 11, 2018

Rooster's Owner

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Dr. Michele K. DVM

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1611 Recommendations

It is possibly Marek's disease, and there is a vaccine that could protect the rest of the flock. I'm not sure if the rooster will recover from this, and it may be a good idea to have them seen by a veterinarian to see if any nursing care is needed.

July 11, 2018

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White Wing

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Amaraucana

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4 Years

pill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filled

Mild severity

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Mild severity

Has Symptoms

Lethargy
Paralysis
Unable To Walk Stable

One of my amaraucana hens was acting strange Thursday. She wouldn't eat or drink, but acted normal despite this. After a night, I found her on the floor of the roost unable to walk stable. She was wobbly and would almost walk on her hocks. It seemed as though she was paralysed. I isolated her from the flock and put her in a box with a towel. Food and water was included. She was lethargic and refused to consume anything for hours. She ended up eating and drinking after a while and today she is more perky and less tired. She eats and drinks correctly and defecates periodically. I'm not sure if it is Marek's disease and I hope it's not, because she could have had it for months without showing signs, but spreading it regardless of that to my flock. I can't got to a vet because of certain reasons and the fact that I may be too late if it is Marek's. I haven't had any history with Marek's and haven't had any other 'mystery' illnesses present in my flock. All deaths were from predation, respiratory issues and one being egg-bound.

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Cookie

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Polish

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3 Years

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Mild severity

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Mild severity

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Cant Get Up Or Walk

Hello I’m confuse I don’t know what my chicken has... she has been paralyzed for 2 years now. She could move but can’t get up or walk. She eats and drinks water. Took her to the vet 2 years ago and they told us she had MD 2 years later and still alive even though vet said she would die... what can it be?

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Baby

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ameraucana

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5 Months

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Serious severity

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Serious severity

Has Symptoms

Laying On Side, Thin

I have a hen that is approx 5-6 months old, she cant stand, or walk, she eats and drinks normally, but she kicks her legs when I hold her. I have had her seperated from the others for about 2 weeks, but not improvement. I have given her B2, B-complex medicated feed, and antibotics, but nothing is working. Can anyone help?

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Kodak

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Black australorp

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7 Months

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Moderate severity

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0 found helpful

pill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filledpill-rating-filled

Moderate severity

Has Symptoms

Slow,
Shut Eye
Slow, One Closed Eye,

My rooster Kodak was lethargic (walking slowly behind his hens, sleeping excessively (standing up), standing in the corner by himself.. so I took him to the vet. They didn’t know what it was and sent us home with 2 weeks worth of an oral antibiotic. I quarantined him right away. It's now 5 days later and I notice he's not always opening his right eye but the eye doesn't appear swollen. He’s eating and drinking well, even taking his medicine well, but doesn’t appear any better nor worse. He perches to sleep at night if that means anything. He’s 7 months old, 7lbs. Thankfully none of his flock have exhibited any such symptoms.

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Black Jack

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Unknown

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5 Months

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Serious severity

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0 found helpful

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Serious severity

Has Symptoms

Diarrhea
Unable To Walk

So my rooster is approx. 5-6 months old. 2 days ago he started not walking well and falling. He does have some diarrhea although today it was a little better. He is getting worse as far as not being able to walk anymore. We have him isolated as of 2 days ago. We have given him his food and we got some electrolyte water with vitamins for chickens. He has been eating and drinking well. Just not able to walk...He doesn't really come off as lethargic...any suggestions/feedback?

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