Getting Started
Conducting a fecal examination to check for internal parasites in your chickens may seem daunting, but with a desire to learn and a little bit of practice, you can most certainly do it. It’s not rocket science!
What am I looking for?
You aren’t looking for actual worms in the feces. Although adult worms are shed in the feces on occasion, especially Ascaridia (roundworms), what is much more prevalent in feces are the eggs that the parasites produce. Parasite eggs are distinct and can allow you to detect the difference between types of parasites that are present.
Why should you care what your chickens have? You need to know whether your chickens have nematodes (roundworms), cestodes (tapeworms) or coccidia so you can decide if you will treat them, and if so, which is the best course of treatment. Medications for one may not be effective at all for others.
Should I be concerned with fecal egg counts?
I am adding this section on fecal egg counts because several people have asked me about this.
With a few exceptions, you aren’t really trying to detect the quantity of parasites in your chickens but are testing for their presence. You may read online about fecal egg counts and wonder why I don't cover these. The number of eggs found in a specific quantity of feces may reflect the severity of the infection, but this is not always reliable in chickens for a few reasons: They don't generally have a huge number of worms in there, and infections range from a few individual worms per bird to a hundred or so in bad infections.
Fecal egg counts are generally done on horses and ruminants, which generally have strongylid worms in very large numbers (thousands and thousands of worms per animal) and which emit a steady stream of eggs into the intestinal tract. So many eggs that it's difficult to count them all. In order to get an accurate count that won't take you a decade, the fecal sample is actually diluted rather than concentrated.
Strongylids in chickens are not a common issue, and you are likely to find only a handful of worm eggs on one slide in a chicken fecal flotation test. You can still get a general impression of the parasite burden in a chicken, though, and you will be able to assess whether you see a whole lot of eggs or just a few in your sample. The actual number of eggs or oocysts may become important when you treat your chickens and want to check them afterward to be sure your treatment worked, but with a chicken, I would recommend a general impression (A few? Medium amount? A lot?) instead of doing a McMaster fecal egg count reduction test (described here), which isn't really sensitive enough for parasites in chickens. Fecal egg counts using the McMaster technique are therefore not covered in this article.
If you still want a fecal egg count, you can follow the procedure for fecal flotation that follows. The only difference is that you will need to weigh the feces before you start. If you mix feces with flotation solution and let the eggs rise to the top, you are theoretically collecting all parasite eggs in that fecal sample. Therefore, if you count every egg on the slide you make, you will be able to know how many worm eggs there were in that sample, and if you weigh the sample, you will know the # of eggs per gram. Ok, back to the topic at hand.
Fecal Flotation technique
To accomplish a fecal examination, feces (stool) is mixed with a solution that causes the parasite eggs to float to the surface. This is exactly why this test is called a “flotation”. When you take the steps to do a fecal flotation test, you are concentrating the worm eggs and causing them to rise to the top of your flotation solution. These eggs are then collected from the surface using a microscope cover slip. The cover slip is placed on a microscope slide, which is examined under a microscope for eggs.
What is a prepatent period?
This is a period of time that passes between the time the chicken becomes infected with the parasite and the time that chicken passes eggs or oocysts in their own feces. In simple terms, the prepatent period is the time it takes to complete one generation of parasites from beginning to end.
Life cycles-direct or indirect?
A parasite that has an indirect life cycle requires an intermediate host somewhere during its little parasite life. This marvel of evolution is pretty common in parasites and requires the chicken to eat the host (or the feces of the host) in order to become infected. Common intermediate hosts are beetles and other bugs and earthworms. The chicken will not become infected without exposure to an intermediate host. Chickens cannot, for instance, pass tapeworms between them directly because they have an indirect life cycle. A parasite with a direct life cycle does not require an intermediate host. A chicken can become infected directly from another chicken. Some parasites can be transmitted directly or indirectly, some only indirectly and some only directly, just to keep things confusing.
A word about feces
The fresher the feces, the better. Feces older than a few days or that have been frozen are not suitable for flotation. Also, feces that have been laying around in the environment for even a short time are very easily contaminated by environmental organisms, so you will end up with things in your results that will only confuse you. The best samples are those that you witness being voided. If you need to store them before testing, put in a plastic bag in the fridge.
What you will need to get started:
Compound microscope
This can be an investment, but it’s pretty easy to find a decent microscope online without breaking the bank. For instance, Amscope and Omax have some decent compound and dissecting microscopes for a little less than $200. A compound microscope is used for looking at very small things, and this is what you’d use to examine fecal flotations. A dissecting scope is for larger objects and is not powerful enough for fecal testing. I recommend a binocular compound microscope, that is, a microscope that has two eyepieces rather than one. It not only encourages much better microscope technique, but you will get a better result and will be able to see and appreciate objects in three dimensions when you use both eyes.
Flotation solution
There are several recipes available and you can even buy it commercially but is also very cheap and easy to make at home using table sugar and/or table salt.
This special solution is essential and takes advantage of physics, and if prepared correctly should be denser than the worm eggs themselves. The density of this solution is known as “specific gravity” (sg) and is expressed as density relative to plain water. Water has a sg of 1.0 and worm eggs have a sg of about 1.2 and, being more dense (much like a tiny rock), will sink in water. Fecal flotation solution should have a sg of about 1.3 so worm eggs will float to the top when in this solution since it’s more dense than the eggs.
Recipe for Salt/Sugar Flotation solution, SG of approximately 1.3:
2 cups warm water
1/3 cup table salt
1/2 cup sugar
Dissolve salt, then stir in sugar until crystals dissolve.
Other necessaries, all of which can be purchased online:
Microscope slides
Cover slips
Test tube or another container that you can sit a cover slip on top
Mesh gauze pads without coating or lining
Tongue Depressors
Tea Strainer
Dixie cups
A quick word about centrifugation
A centrifuge is a machine that spins things really fast, and acts to separate solutions by density. You may read online about how centrifugation is the preferred method for fecal flotation testing, and that's absolutely true. The evidence is very consistent that you will get better worm egg recovery if you use a centrifuge for your fecal flotation tests. I purposefully didn't include centrifugation in this method, however, because this article is aimed at the home operator and backyard chicken enthusiast. A centrifuge is a relatively expensive and specialized piece of equipment, and most people don't have one lying around the house. This article is meant to be approachable by anyone with a desire to learn. If you want to buy or use a centrifuge, by all means, do it! It can be a dangerous machine if you are unfamiliar, and while it absolutely does give a better and more sensitive result, flotation testing can certainly be done without one. If you are interested in purchasing one or have access to one, here's some reading on why centrifugation is best practice. Dr. Blagburn is one of the most respected parasitologists in the world, and not only does he have really great hair, he even has a parasite (Tritrichomonas blagburni) named after him! (how cool is that!?)
https://www.dvm360.com/view/why-fecal-centrifugation-better
Ok, back to the topic at hand. Let’s get this party started.
Open a square of gauze and line a tea strainer (you want 2 layers of gauze).
With a tongue depressor, mix a blob of fresh feces about the size of a lima bean thoroughly with about 10 ml flotation solution in a Dixie cup:
then pour the mixture through the tea strainer into a second Dixie cup
Pour the strained solution into a test tube and fill all the way to the top with more flotation solution so a small meniscus forms.
Don’t over-fill the tube since this may result in loss of floated eggs so the right tube in the figure above will work best.
If you look closely now, you will see material slowly rising to the top of the tube.
Drop a coverslip gently right on top of the tube so it contacts the liquid. You might get a drop or two that overflows. That’s ok. Now let the sample stand for 20 minutes. Don’t cheat on time! The eggs need time to float up to the cover slip.
After time is up, remove the coverslip by pulling it straight up in one swift motion and place it, liquid side down, on a glass slide.
A little hard to see, but you can make out the coverslip between my fingers and to the left of the slide if you look closely. Note drop of liquid on underside of the cover slip. That’s where all the good stuff is.
Now drop the coverslip liquid side down onto a microscope slide. It will quickly adhere to the slide and the liquid will spread out.
That’s it! You did it!
But wait, there's more! Click here to continue on to Part II
Conducting a fecal examination to check for internal parasites in your chickens may seem daunting, but with a desire to learn and a little bit of practice, you can most certainly do it. It’s not rocket science!
What am I looking for?
You aren’t looking for actual worms in the feces. Although adult worms are shed in the feces on occasion, especially Ascaridia (roundworms), what is much more prevalent in feces are the eggs that the parasites produce. Parasite eggs are distinct and can allow you to detect the difference between types of parasites that are present.
Why should you care what your chickens have? You need to know whether your chickens have nematodes (roundworms), cestodes (tapeworms) or coccidia so you can decide if you will treat them, and if so, which is the best course of treatment. Medications for one may not be effective at all for others.
Should I be concerned with fecal egg counts?
I am adding this section on fecal egg counts because several people have asked me about this.
With a few exceptions, you aren’t really trying to detect the quantity of parasites in your chickens but are testing for their presence. You may read online about fecal egg counts and wonder why I don't cover these. The number of eggs found in a specific quantity of feces may reflect the severity of the infection, but this is not always reliable in chickens for a few reasons: They don't generally have a huge number of worms in there, and infections range from a few individual worms per bird to a hundred or so in bad infections.
Fecal egg counts are generally done on horses and ruminants, which generally have strongylid worms in very large numbers (thousands and thousands of worms per animal) and which emit a steady stream of eggs into the intestinal tract. So many eggs that it's difficult to count them all. In order to get an accurate count that won't take you a decade, the fecal sample is actually diluted rather than concentrated.
Strongylids in chickens are not a common issue, and you are likely to find only a handful of worm eggs on one slide in a chicken fecal flotation test. You can still get a general impression of the parasite burden in a chicken, though, and you will be able to assess whether you see a whole lot of eggs or just a few in your sample. The actual number of eggs or oocysts may become important when you treat your chickens and want to check them afterward to be sure your treatment worked, but with a chicken, I would recommend a general impression (A few? Medium amount? A lot?) instead of doing a McMaster fecal egg count reduction test (described here), which isn't really sensitive enough for parasites in chickens. Fecal egg counts using the McMaster technique are therefore not covered in this article.
If you still want a fecal egg count, you can follow the procedure for fecal flotation that follows. The only difference is that you will need to weigh the feces before you start. If you mix feces with flotation solution and let the eggs rise to the top, you are theoretically collecting all parasite eggs in that fecal sample. Therefore, if you count every egg on the slide you make, you will be able to know how many worm eggs there were in that sample, and if you weigh the sample, you will know the # of eggs per gram. Ok, back to the topic at hand.
Fecal Flotation technique
To accomplish a fecal examination, feces (stool) is mixed with a solution that causes the parasite eggs to float to the surface. This is exactly why this test is called a “flotation”. When you take the steps to do a fecal flotation test, you are concentrating the worm eggs and causing them to rise to the top of your flotation solution. These eggs are then collected from the surface using a microscope cover slip. The cover slip is placed on a microscope slide, which is examined under a microscope for eggs.
What is a prepatent period?
This is a period of time that passes between the time the chicken becomes infected with the parasite and the time that chicken passes eggs or oocysts in their own feces. In simple terms, the prepatent period is the time it takes to complete one generation of parasites from beginning to end.
Life cycles-direct or indirect?
A parasite that has an indirect life cycle requires an intermediate host somewhere during its little parasite life. This marvel of evolution is pretty common in parasites and requires the chicken to eat the host (or the feces of the host) in order to become infected. Common intermediate hosts are beetles and other bugs and earthworms. The chicken will not become infected without exposure to an intermediate host. Chickens cannot, for instance, pass tapeworms between them directly because they have an indirect life cycle. A parasite with a direct life cycle does not require an intermediate host. A chicken can become infected directly from another chicken. Some parasites can be transmitted directly or indirectly, some only indirectly and some only directly, just to keep things confusing.
A word about feces
The fresher the feces, the better. Feces older than a few days or that have been frozen are not suitable for flotation. Also, feces that have been laying around in the environment for even a short time are very easily contaminated by environmental organisms, so you will end up with things in your results that will only confuse you. The best samples are those that you witness being voided. If you need to store them before testing, put in a plastic bag in the fridge.
What you will need to get started:
Compound microscope
This can be an investment, but it’s pretty easy to find a decent microscope online without breaking the bank. For instance, Amscope and Omax have some decent compound and dissecting microscopes for a little less than $200. A compound microscope is used for looking at very small things, and this is what you’d use to examine fecal flotations. A dissecting scope is for larger objects and is not powerful enough for fecal testing. I recommend a binocular compound microscope, that is, a microscope that has two eyepieces rather than one. It not only encourages much better microscope technique, but you will get a better result and will be able to see and appreciate objects in three dimensions when you use both eyes.
Flotation solution
There are several recipes available and you can even buy it commercially but is also very cheap and easy to make at home using table sugar and/or table salt.
This special solution is essential and takes advantage of physics, and if prepared correctly should be denser than the worm eggs themselves. The density of this solution is known as “specific gravity” (sg) and is expressed as density relative to plain water. Water has a sg of 1.0 and worm eggs have a sg of about 1.2 and, being more dense (much like a tiny rock), will sink in water. Fecal flotation solution should have a sg of about 1.3 so worm eggs will float to the top when in this solution since it’s more dense than the eggs.
Recipe for Salt/Sugar Flotation solution, SG of approximately 1.3:
2 cups warm water
1/3 cup table salt
1/2 cup sugar
Dissolve salt, then stir in sugar until crystals dissolve.
Other necessaries, all of which can be purchased online:
Microscope slides
Cover slips
Test tube or another container that you can sit a cover slip on top
Mesh gauze pads without coating or lining
Tongue Depressors
Tea Strainer
Dixie cups
A quick word about centrifugation
A centrifuge is a machine that spins things really fast, and acts to separate solutions by density. You may read online about how centrifugation is the preferred method for fecal flotation testing, and that's absolutely true. The evidence is very consistent that you will get better worm egg recovery if you use a centrifuge for your fecal flotation tests. I purposefully didn't include centrifugation in this method, however, because this article is aimed at the home operator and backyard chicken enthusiast. A centrifuge is a relatively expensive and specialized piece of equipment, and most people don't have one lying around the house. This article is meant to be approachable by anyone with a desire to learn. If you want to buy or use a centrifuge, by all means, do it! It can be a dangerous machine if you are unfamiliar, and while it absolutely does give a better and more sensitive result, flotation testing can certainly be done without one. If you are interested in purchasing one or have access to one, here's some reading on why centrifugation is best practice. Dr. Blagburn is one of the most respected parasitologists in the world, and not only does he have really great hair, he even has a parasite (Tritrichomonas blagburni) named after him! (how cool is that!?)
https://www.dvm360.com/view/why-fecal-centrifugation-better
Ok, back to the topic at hand. Let’s get this party started.
Open a square of gauze and line a tea strainer (you want 2 layers of gauze).
With a tongue depressor, mix a blob of fresh feces about the size of a lima bean thoroughly with about 10 ml flotation solution in a Dixie cup:
then pour the mixture through the tea strainer into a second Dixie cup
Pour the strained solution into a test tube and fill all the way to the top with more flotation solution so a small meniscus forms.
Don’t over-fill the tube since this may result in loss of floated eggs so the right tube in the figure above will work best.
If you look closely now, you will see material slowly rising to the top of the tube.
Drop a coverslip gently right on top of the tube so it contacts the liquid. You might get a drop or two that overflows. That’s ok. Now let the sample stand for 20 minutes. Don’t cheat on time! The eggs need time to float up to the cover slip.
After time is up, remove the coverslip by pulling it straight up in one swift motion and place it, liquid side down, on a glass slide.
A little hard to see, but you can make out the coverslip between my fingers and to the left of the slide if you look closely. Note drop of liquid on underside of the cover slip. That’s where all the good stuff is.
Now drop the coverslip liquid side down onto a microscope slide. It will quickly adhere to the slide and the liquid will spread out.
That’s it! You did it!
But wait, there's more! Click here to continue on to Part II
