What To Do If A Chicken Is Losing Weight?

Raising chickens can be a lot of fun but it does have its more serious moments too, one thing that can really get a chicken’s owner worrying is when a chicken starts losing weight.

What to do if a chicken is losing weight? You need to identify why the chicken is losing weight: nutritional deficiency, stress, disease, parasites, extreme weather conditions, over-crowding, debeaking, vaccinations or unusual conditions and then take the appropriate action, where possible, to counteract the problem.

It’s important to remember that chickens live to eat and thus losing weight is almost always the sign of a real problem – so, you must be prepared to take immediate action. Fortunately, we’ve got the information you need to tackle it head on.

9 Reasons Your Chicken May Be Losing Weight And What Do To About It

Chickens are both simple creatures and very complex ones at the same time. They’re not the brightest of birds and most of a chicken’s life is spent in pursuit of food with reproduction (and those glorious eggs we love them for) coming in a close second place.

However, their biology is much more complicated than their personalities and chickens can be quite difficult to diagnose when it comes to the issue of losing weight. We’ve outlined 9 of the top reasons for weight loss and how you might take action on each issue.

But… if you cannot readily identify a problem, it’s usually better to seek expert help from a veterinarian that to continue to try and guess at the problem. It doesn’t take long for hunger to stop a chicken from laying and they can’t go that long without food before they die from starvation.

So, if in doubt – call a vet. Please.

Nutritional Deficiencies in Chickens

Chickens will normally show other symptoms of nutritional deficiency before they stop eating and these symptoms can include: a lack of energy, abnormal feather appearance, loss of pigment in the feathers, skin lesions, dermatitis, keratinization of the mucous membranes (this is where the mucous membranes become covered in a hard protein – keratin which is the same stuff as makes up hair and nails), muscular degeneration, bone deformation and brittle bones, decreased or lost egg production, poor quality eggs, and neurological disorders.

That means that if a chicken isn’t eating because of a dietary deficiency the end is surely coming. You cannot diagnose a vitamin deficiency easily by sight and if the problem is a selenium (mineral) deficiency then trying to treat it yourself may kill the bird (too much is as bad as too little in this case).

Chickens can lack some or all of the following in their diet: Vitamin A, D3, E, K, B12, Choline, Niacin, Pantothenic Acid, Riboflavin, Folic Acid, Biotin, Pyridoxine (B6), Thiamine, Calcium, Potassium, Manganese and Selenium. In an ideal world, the chickens would be able to find everything they need in feed plus what they can forage whilst grazing but sometimes things don’t go according to plan.

So, if you think there might be a nutritional deficiency in the flock, you need to get your local vet to arrange for a blood test (or tests) to determine what’s missing and how you should add it back into the bird’s diet.

The good news is that most of the damage is normally reversible for a nutritional deficiency if you get a vet to treat it early enough.

Stress In Chickens

Stress is such a serious problem in chickens that Poultry World magazine dubbed it “the silent killer”. They weren’t being melodramatic about things either. Chickens are rather like human beings in both their ability to get stressed and their inability to deal with it.

There are no chicken gurus offering meditation classes and while roosters are only too happy to lavish as much “free love” as a hen can want, it won’t help with stress. So, you need to take charge if you think your flock is showing signs of stress.

The five most common signs of stress are weight loss, a reduction in egg production, a reduction in their ability to live, an increase in feed conversion and immuno-suppression.

The good news is that treating stress in chickens can be done quite easily through the removal of the source of stress (if possible) and by adding nutritional supplements to the flock’s feed.

You want supplements designed to:

  • Combat stress on a variety of fronts through multiple means
  • That promote better digestion and the uptake of nutrients in the good
  • That offer improved feed intake, weight gain and feed conversion
  • That promote the restoration of microflora in the gut if the birds have recently undertaken courses of antibiotics or other forms of chemical/drug therapy

If you can’t manage to cure their stress with this kind of treatment – it’s definitely time to get a vet involved and see what they can find that you may have missed.

Extreme Weather Conditions

One cause of stress in chickens that can be very difficult to deal with is extreme weather conditions, it’s not unknown for chickens to go off their food for a little while following a huge storm or in the middle of a summer that’s unusually hot.

You can take some action to make the birds more comfortable in the event of long-lasting weather events for example installing fans (suitable for use with birds not just desk fans) or air-conditioning of some form in the coop but most of the time extreme weather events are short-lived and the fall out is minor.

Over-Crowding In The Chicken Coop

Another potential problem that can cause serious stress in birds is over-crowding in the chicken coop. If this happens, the smaller, weaker chickens in the pecking order are likely to bullied and forced to stay away from food, drink and bedding. If you are concerned that your chickens might be getting bullied then head over and read one of our other articles all about chickens pecking order.

As you can imagine this is going to cause some weight loss through the chicken not getting enough to eat but it’s important to realize that this is a minor problem compared to what may happen if you don’t resolve the over-crowding issue.

If chickens are crammed in together for too long, they may refuse to lay and eggs that are laid may be abnormal or covered in chicken poop. Worse, if they’re left alone for long enough and the overcrowding doesn’t go away – chickens can turn cannibal.

They’ll turn on the weakest birds and peck them to death and then consume them. This is, as far as nature is concerned, a way of bringing balance to a flock but as far as an owner is concerned this can be one of the most traumatic things they have to deal with.

It’s always better to either make more space in the coop (by getting a bigger one) and the nesting boxes or to get rid of the excess chickens in a humane fashion before their flock takes matters into their own hands.

Unusual Conditions (Noise, Transport, etc.)

Other potential triggers of stress can be hugely varied – one thing’s for certain chickens aren’t partial to long sustained burst of loud noise and if they are regularly subjected to a loud stereo or TV or car motor, etc. they may quickly become stressed and depressed.

Some chickens also don’t react particularly well to being transported and they may, after a journey, lose their appetite. However, we wouldn’t expect this to last for much more than a few hours and if the chicken’s still not eating a day later, there’s something bigger on their mind than being driven around. 

Impacted Crop

One of the most common injuries to a chicken is an impacted crop it can be caused by trauma or disease, but the outcome is always the same.

The crop is a shelf in the throat just off the esophagus that plays a minor role in digestion. Chickens can’t chew as they have no teeth, so what happens is they soak all their food in saliva and then swallow it.

Instead of heading straight to the stomach, it stops at the crop and sits on the shelf (mainly marinating in enzymes from saliva) before moving on to the stomach as needed.

A chicken’s hunger reflex comes not from its stomach but from its crop. When the crop is empty, it gets hungry.

Unfortunately, when the crop is impacted it is unable to take on food or to let it pass on to the stomach and an early warning sign of the condition is a chicken regurgitating its food.

The chicken will then begin to lose weight as it stops eating. Sometimes the crop can be badly swollen enough that it blocks the throat and prevents the chicken from breathing. The good news is that an impacted crop can be easily treated with a minor operation at the vet.

4 Common Diseases That Can Cause Weight Loss In Chickens

There are many different diseases in chickens which can cause weight loss but the four most common are:

Marek’s Disease

Marek’s disease is named after the Hungarian vet that isolated it. It is a fairly common problem in chickens and an early warnings sign that your flock may be infected with Marek’s is weight loss. There is a vaccine for this condition, but it can’t stop the chickens from catching Marek’s only from becoming symptomatic. Your vet should have explained whether or not your flock needs this vaccination at your first consultation with them.

Fowl Pox

Fowl pox is a viral infection that spreads relatively slowly through a flock. It causes painful lesions on the face, mouth and respiratory tract. It rarely kills its victims unless the respiratory infection is particularly severe. However, it can cause depression as well as the loss of appetite due to the pain. It takes five weeks to heal and there is no known cure. There is, however, a vaccine that is fully-preventative.

Fowl Cholera

Fowl cholera, rather like human cholera, can cause a large amount of continuous diarrhea as you might expect this will lead to weight loss in the birds. It is a bacterial disease that can be treated with antibiotics and completely eliminated through eradication efforts. Your vet will advise on what must be done.

Avian Leucosis

Avian Leucosis rather like Marek’s disease causes tumors in the chicken which can block the throat and prevent the chicken from eating. There is no treatment, no vaccine and no cure for Avian Leucosis and the best preventative measure appears to be keeping the area with the chickens in spotlessly clean and separating sick birds until they either recover or perish.

4 Common Parasites That Can Cause Weight Loss In Chickens

There are four common parasitic conditions which can cause weight loss in chickens and they are:

Lice Infestations

Chickens are very susceptible to lice and most of the time their regular dust baths will keep them under control if not completely at bay. However, occasionally a lice infestation can get out of control and the pain that it causes will lead to the chicken losing appetite and thus losing weight. Fortunately, it’s easy to treat with insecticides prescribed from a vet.


This is a parasitic infection of the gut which is caused by eating the parasites. The normal treatment when a flock is infected with Coccidiosis is a drug called amprolium (which is most commonly sold under a brand name “Corid”). It’s mixed into their water or given directly by mouth and it will quickly go away after treatment.

Roundworm (Ascariasis)

This is an exceptionally common condition in most chickens and is often not a problem at all. It becomes an issue when a worm gets lost inside the chicken’s body and ends up in the crop or an ovary or somewhere else it shouldn’t be. Treatment is, fortunately, very easy too and a deworming agent will quickly send the roundworm packing.

Hairworm (Capilliariasis)

Possibly the most dangerous worm infection in chickens is hairworm, so called because the worms look like very short hairs. They can really cause severe pain in chickens and severe diarrhea leading to rapid weight loss. Again, they’re reasonably easy to treat and a vet should be able to recommend a deworming product that rids your chickens of hairworm very quickly.

Vaccination Responses

There are a variety of vaccinations for chickens and your vet or breeder should be able to advise you on the right choices for your flock. It’s important to note that vaccinations in chickens are thoroughly effective and are not known to have any long-term negative health impacts of any kind.

However, there may be a short period of time following a vaccination that a chick or adult bird shows a set of responses to the vaccination. One of these responses may be loss of appetite. This shouldn’t last very long and if it does, you should consult with a vet to see how it might be remedied.


So, what to do if a chicken is losing weight? As you can see this isn’t an easy question to answer and it depends on what’s wrong with the bird as to what action you should take. Our 9 main causes of sudden weight loss in chickens ought to be able to help you narrow things down a bit but if you’re not certain – call the vet.

As chickens are all about eating, weight loss is a sign of a real issue and failing to take action might lead to long-term problems with laying or even the death of your chicken, so it’s best not to take any risks with this.

Here are some of my favorite products for chickens and their coops:

Darren Black

I'm Darren Black, the owner, and author of AnimalKnowhow.com. I am from Scotland, United Kingdom and passionate about sharing useful information and tips about properly caring for an animal's wellbeing.

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