Emergencies/Illness Health Issues

Thiamine (Vitamin B1) Deficiency In Chickens

Chickens can experience complications from a variety of vitamin deficiencies and their symptoms are often mistaken for other health issues.

Lots of you are aware that wry neck can be a result of a vitamin E and selenium deficiency, but it can also be caused by a lack of thiamine. In this piece I’ll explore that happens when chickens don’t get enough thiamine (vitamin B1). In case you’re not familiar it’s one of eight water-soluble B vitamins that strengthens the immune system and improves the body’s ability to withstand stress.

Thiamine is essential for the production of energy from glucose or the conversion of glucose to fat storage. The brain’s energy comes from the breakdown of glucose, a biochemical process requiring thiamine. Without it basic energy functions are impacted leading to systematic problems. When your birds are deprived of thiamine they become more vulnerable to neuromuscular issues and those affecting the heart, nervous and digestive systems.


  • Loss of muscle control and coordination (ataxia)
  • Head tremors, which can increase in severity
  • Muscle paralysis starting with the toes and moving upward to the legs, wings and neck
  • Sitting on flexed legs, with the neck in a stargazing position (wry neck)
  • Paralysis of the muscles at the back of the neck
  • Inability to stand or sit upright
  • Lethargy
  • General weakness
  • Impaired digestion
  • Severe loss of appetite (unless given food containing thiamine)
  • Severe weight loss
  • Frequent convulsions
  • High mortality rate in hatching eggs produced by affected parents


  • Separate bird from flock in a warm, quiet place
  • Provide increased dietary thiamine or poultry vitamins containing thiamine in drinking water
  • Administer vitamin B1 orally (1-2 mg/kg for 24hrs) or via injection (1-3 mg/kg for 7 days)


  • Ensure provision of a well-balanced feed
  • Light weight breeds (e.g. Leghorns) have higher requirements for thiamine than heavy breeds (e.g. Orpingtons)
  • Older chickens utilize vitamins less efficiently and therefore are more vulnerable to deficiencies
  • Birds given diets containing high carbohydrates and table scraps often require more thiamine
  • If giving birds medicated feed or Corid (amprolium) ensure they are provided poultry vitamins or thiamine rich foods once finished with those products: Brewer’s yeast, soybeans, lentils, beans, brown rice, cereal grains, fish, eggs, leafy greens and tofu
  • Moldy feed can result in nutrient loss, including thiamine

When I scroll through posts on Facebook chicken groups from folks asking for help with their birds’ health issues some of the most common responses are suggestions to suspect/treat for: egg binding, gapeworm, Marek’s disease and coccidiosis. I have dealt with three out of those four and hazard a guess that many of those well-meaning diagnoses are actually incorrect.

What is more troubling is that some group members direct folks on a course of treatment, often including medications and antibiotics, that may be unwarranted and actually harmful. A case in point is the common belief supporting wormers and anti-coccidials as a routine preventative or a treatment for a suspected condition.

The most common remedy used for coccidiosis is Corid which contains amprolium, a thiamine-blocker used to disrupt the reproductive cycle of coccidia. It’s effective, but can also contribute to a thiamine deficiency especially if it is given in the wrong dosage or for a prolonged period of time.

One study found that amprolium fed to hens “produced lowered feed intake, decreased rate of lay, increased embryo mortality, and lowered chick viability at hatch”.

The symptoms of insufficient thiamine often mimics other conditions, including Marek’s Disease. I wonder how many people, who were under the assumption their chicken had the neurological form of Marek’s, failed to recognize and treat for a simple vitamin deficiency. There are probably others whose birds have died untreated, or been culled for fear they had something contagious.

I found this in an online chicken group and thought it might be useful:

“I recently did a necropsy on a rooster that was experiencing neurological signs. There were several other chickens in their flock experiencing similar signs and dying within a matter of days. The owners were devastated and thought they had a bad case of Marek’s Disease. The necropsy of the rooster revealed absolutely no abnormalities to any organs. No signs of disease.

The same owners brought me one of their live chickens the next day for an exam. Ataxic, difficulty walking, head tremors, inappetance and lack of proprioception (lack of balance). After getting a lot of history from the owner, it turns out that their chickens were experiencing intermittent diarrhea. They were given advice, on a Facebook group, to give a treatment of Corid to treat coccidia. These owners were never given a diagnosis of coccidia or parasites. The diarrhea went away, so they assumed that the diarrhea was because of parasites. Anytime their flock had diarrhea, they used Corid.

An important thing to know about using Corid, or any medicated feed with Amprolium, is that it decreases Vitamin B1. Thiamine deficiency in adult chickens causes all of the clinical signs listed above. In young birds/chicks, you may see wry neck or stargazing. These chickens were getting sick and then dying, because of thiamine deficiency. The Corid was depleting their bodies of an essential vitamin.

I share this case because of my concern of people giving advice without knowing history of an animal, the lifestyle, food, deworming protocols, or diagnostic results. Veterinarians order certain diagnostics and treat diseases appropriately according to those diagnostics. There is a small percentage of non-vets on this page that know a great deal about chickens and other fowl, but no one, except a veterinarian should be diagnosing or offering medical advice, especially when it comes to giving medications.” – Dr. Nicole M. Headlee, DVM

Credits: DSM in Animal Nutrition & Health; Dr Nicole Headlee, DVM; Journal of Nutrition; Merck Veterinary Manual and Poultry DVM.  Featured Image: Poultry DVM

10 comments on “Thiamine (Vitamin B1) Deficiency In Chickens

  1. Thank you for this article.
    I found it very informative and helpful.

    I currently have a 5 week old Orpington chick that is showing symptoms of a vitamin deficiency similar to what you’ve described.

    She is still eating and drinking some and vocalizes…she even still tries to peck and scratch…but she easily falls over and cannot seems to get back up easily. When she is upright she is reluctant to fully stand but mainly relies on and leans back onto what seems like her back knees.

    No sign of exterior trauma, so I believe it’s internal.

    She has been on an organic chick starter/grower with probiotics from day one.
    And I have been putting ACV in her water.

    Since her symptoms I have separated her and given her boiled egg yolk with diced spinach and some brewers yeast to boost thiamine and riboflavin and other vitamins.
    I also put a vitamin mix into her water….it is also laced with electrolytes, so I hope that’s ok.
    I did administer some of this water with a syringe and she drank about 4mil.

    How often should I feed her this egg mixture and administer vitamin water?
    And would u suggest anything specific for her young age?

    Do you have any other ideas to promote recovery?

    Thank you.

    Liked by 2 people

    • I would give continue to give her probiotics and electrolytes. Can you mix her starter crumbles with a bit of water and make a mash so it’s easier to eat? I would discontinue the apple cider vinegar. It’s an acidifier, used to balance pH levels, but can be hard on the digestive system. I would wait a few months before introducing ACV to chicks. Be careful giving water via syringe as it’s easy to get some into their lungs and aspirate them. Dip her beak in water or offer water from a spoon.

      Liked by 1 person

  2. The main function of the D vitamin is to help control how much calcium is absorbed from food. A lot of the calcium is used to make strong teeth and bones but additionally it is needed to send messages over the nerves and help muscles, including the heart muscles, to contract|


  3. Wanda Jackson

    Have a 6.5 lb 11 month old rooster who suddenly became lame & displayed symptoms of wry neck 4 days later. He has always been very alert & had a good appetite. Have kept him in a small dog pen for 3 weeks. Changed to food with selenium & supplemented with Vit E. Did worm during this time. Leg problem has displayed little improvement. Took to vet & had xrays on leg. No problem detected.
    No wounds or injuries detected. He still will not put food on leg. Bought him as chick & used medicated chick food. Today, I began adding Thiamine to his food. His legs look symmetrical with no obvious weaknesses. He just will not put weight on that leg. When I touch his feet, they are much less responsive on his weak leg.

    Liked by 1 person

    • What are you feeding him? If you put your finger under his foot pad can he curl his toes around it? Did you check out my post called “Help, My Chicken Is Limping’? Just put ‘limping’ in the search box and you’ll find it.


  4. Thank you! When people ask about a bird and suspect wry neck or Marek’s, I always ask what they are feeding or supplementing with. Since we know vitamin E and Selenium are often implicated in wry neck I always see that recommended first in poultry groups. I try to warn people to be careful what they supplement, especially with, for example, selenium, as there is a VERY narrow window between therapeutic and toxic.

    And of course, head trauma can cause a similar presentation – which is more common in crested breeds (especially if they have a vaulted skull).

    However, when a bird is younger, my first question is usually has it been eating medicated starter? Amprolium (the medication in medicated starter) is a thiamine antagonist and blocks the thiamine receptors – preventing coccidia from utilizing thiamine – which coccidia need to survive, preventing coccidiosis. But unfortunately, over a longer term, this can cause a thiamine deficiency – which can present with torticollis (otherwise known as ‘wry neck’). If a chicken has been on a medicated feed, I always recommend switching to an unmedicated and trying a B complex vitamin.

    Liked by 1 person

  5. I am having a hard time locating a proper thiamine injectable solution for poultry. Any suggestions?

    Liked by 1 person

  6. I have a 2 day old chick. She has been sleeping a lot since she hatched. At first we thought it was just the effort of hatching because she was eating and drinking a little. This morning she is struggling to stay standing and is having head tremors.

    I have been giving her egg yolk and just gave her a vitamin/electrolytes supplement in her water that contains thiamine.

    I’m not sure if it’s the correct thing to do at this young age. All her hatch mates are doing very well.

    Any advice would be appreciated.

    Liked by 1 person

    • She may be weak from a prolonged hatch or was weak to start with. I think you’re doing the right thing by keeping her hydrated and giving her a boost with vitamins and electrolytes. Good luck with her.


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