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

3 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|


Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.

Bitchin' Chickens

Everything You Need To Know About Small Flock Chickens & More

%d bloggers like this: