Chickens With Worms and Deworming Chickens — Randy’s Chicken Blog

Other signs are less specific. When hens have a high worm load, they can have diarrhea, lose weight, look scruffy, lay fewer eggs, and become less active. But, of course, they can also display all of those same symptoms as the result of all sorts of other maladies.

What should you do if your flock or some individuals in your flock are noticeably unhealthy with some or all of these nonspecific symptoms? One option: You can treat for worms using a chemical dewormer. If you see a noticeable improvement after deworming, you know that worms were the problem and that you’ve solved it. A better option: You can perform a fecal test for worms. A positive test showing a high worm burden would show that worms really are causing your flock’s health issues.

Some avian vets and chicken experts maintain that you should proactively deworm your flock on a regular basis to periodically knock down the worm population and prevent a high worm load. Most recommend once or even twice a year. I’ve always followed that advice and have been routinely deworming my flock ever since I got my first chickens.

Recently, though, after some reading and research, I’ve changed my mind. I’ve discovered that there are also avian vets and chicken experts who caution against regular deworming. I’ve come to see their point. There are compelling reasons not to deworm my birds on a regular schedule. I’ve stopped. It’s a big shift for me and my flock. Here’s why I changed my mind.

1 – Chickens can carry around a reasonable number of worms and live normal healthy lives

Deworming carries certain risks and can be disruptive and stressful to my flock. If my hens are healthy, why should I subject them to that?

2 – There is only one approved treatment option

Fenbendazole is currently the only FDA cleared chicken dewormer in the US. It has clearance for the treatment and control of two worms; roundworms (Ascaridia spp.) and cecal worms (Heterakis spp.) in chickens and turkeys.

Any other wormers suggested to me by my neighbor, my vet, or that on-line forum, are potentially effective. But I would be using them “off label.”  None of them are FDA cleared, and no licensed clinical trials have been done. Without the scientific rigor of clinical trials, any directions regarding dosage, toxicity, efficacy, and carryover of the drug into eggs are based on studies and trials that lack the stringency and comprehensiveness required for clearance.

Deworming chemicals that are commonly used off-label to deworm chickens are all approved for deworming other animals. So, why haven’t the manufacturers of these dewormers worked to get their products approved for chickens?

For drug manufacturers to get clearance, they must perform rigorous testing on each drug with each type of animal and each species of parasite. Then they have to formally submit their research results to the federal licensing bodies. It costs millions of dollars to get one dewormer approved for one animal.

And most commercial egg producers keep their hens in cages; indoors, sequestered in small groups, and off the ground. Thus, while the millions of chickens living in cages are living tortured lives, they don’t have worms and don’t need dewormers.

That leaves that small subset of happy birds scratching in the dirt as the only ones exposed to worms: Commercial chickens free-ranging in pastures, breeder flocks, and backyard chickens. Dewormer manufacturers simply aren’t going to spend all that cash to get clearance for this tiny market.

3 – Worms become resistant

Worms can become resistant after frequent, repeated use of the same dewormer. And worms subjected to different but related dewormers can develop resistance to all the dewormers that are in the same chemical family. The Poultry DVM website’s comprehensive directory of dewormers for chickens lists a mere ten deworming drugs for chickens: Fenbendazole and nine off-label drugs. Three of the off-label drugs are in the same benzimidazole family as Fenbendazole. The arsenal is small. So, frequent, repeated use of the same dewormer is unavoidable when flock owners are deworming on a regular basis.

The Merck Veterinary Manual affirms that “the number of medications approved for treatment of helminthiasis in poultry is decreasing. There are also reports of resistance developing.” Their suggested solution to that dilemma? “To decrease the potential spread of resistance, treatment should be limited to birds with severe infestation that show clinical signs of disease.” (my emphasis) “Such targeted treatment also seems to more effectively decrease worm burden and cumulative environmental parasite egg numbers than untargeted routine treatment.”

4 – Not all dewormers treat all worms

FDA-approved fenbendazole has demonstrated good broad-spectrum effect against all the common nematodes (capillary worms, cecal worms, gapeworms and roundworms) and is also effective against tapeworms. Fenbendazole’s off-label cousins, the various benzimidazoles, are also fairly broad-spectrum. Most of the other off-label wormers have a narrower range. Ivermectin, for example doesn’t work against tapeworms.

If I want broad-spectrum coverage, my choice is to always treat with fenbendazole or a related off-label dewormer. But, if I’m worming my flock a couple of times a year, that’s a terrible strategy! Constant repeated use risks developing resistance. The alternative is to alternate fenbendazole with a one or more of the off-label wormers that are more narrowly focused. And with that strategy I know that I’m not treating for whole categories of worms. Neither choice is a good one.

5 – Reinfestation

The Chicken Coach website explains reinfestation succinctly. “There’s no point in worming your flock unless you first address their environment and diet. If you don’t, you’ll just have the problem return in a few weeks’ time.”

If my hens have worms, I can assume that they’ve been pooping worm eggs all over their run. Some worm eggs can remain viable in the soil for several years. If I don’t want my hens to consume worm eggs when they peck and scratch at the soil and become immediately reinfested, I would need to move them to a completely new area. Unfortunately, the fence surrounding my run is a pretty permanent structure. So, a new run isn’t going to happen. I’m sure that most backyard flock keepers can tell the same story.

So, what’s the point of taking my birds through a deworming process when they’ll become reinfested in short order?

6 – Toxicity

A doctor once presented me with this interesting idea: “All medicines are poisons with one good side-effect.” He was probably riffing on the classic toxicology aphorism coined by the 16th century Swiss physician, Paracelsus, who said, “All things are poison, and nothing is without poison; the dosage alone makes it so a thing is not a poison.” Most toxicologists remember this as: “The dose makes the poison”

The point is that wormers are powerful chemicals that kill worms. Worms are animals – and chickens are animals, so any chemical toxic enough to kill worms can also potentially harm chickens. A chemical that is medicinal becomes poisonous when it’s used incorrectly. So, read labels carefully. Follow instructions scrupulously, and if the product is off-label, follow the guidelines of known, trusted sources.

Also, be aware of potential side-effects. Fenbendazole, for instance, can cause deformed feathers if it is administered during a molt while feathers are being formed.

And finally, don’t use dewormers indiscriminately. Which brings us back to my point that if your flock is loaded with worms, deworm them. If they appear healthy, don’t stress them with deworming chemicals.

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Worms come from worm eggs. The eggs are either consumed by your chickens or by a slug/earthworm/insect intermediate host which is then consumed by your chicken. And worm eggs come from chicken poop of infested chickens (or other birds). Control the poop and you control the problem.

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Periodically switch to new a run space if you can. Caveat: That’s simply not practical for most backyard flock keepers.

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If your flock is permanently in the same run, keep the run meticulously clean. If your run is small, it would probably not be too odious to remove and compost the top few inches of soil occasionally and replace it with fresh sand.

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Worms thrive in warm, humid environments. You can’t control the weather, but you can respond to it. Don’t build your run in low areas where water pools. If the run area is low, build it up with dirt or sand. If your run area is small, roof it to keep it dry.

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To avoid the spread of resistance, and for all the reasons listed in the previous sections, do NOT deworm periodically and indiscriminately.

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I’m bolding this, because it’s so important. Check for worms on a regular basis by fecal exam and if the worm load is high, THEN deworm. And THEN think about how you can improve your flock’s environment.

While there have been some recent advances in methods for testing for worms, like PCR and antigen testing, most of the new methods are not readily available for routine vet testing and are mostly being used for research purposes. The gold standard is to concentrate a fecal specimen by flotation or sedimentation, and then examine the concentrate under a microscope for the presence of worms and other parasites. While it’s possible to find an actual worm in a fecal specimen, what you’re really looking for is the presence of worm eggs. There are three ways this test can be accomplished.

Do it yourself

Gail Damerow, in The Chicken Health Handbook suggests that anybody can check their flock for worms. She offers up some good solid instructions for collecting a sample and concentrating it using a flotation method.

If you follow her advice and do your own testing, you will, of course, need a microscope. You can purchase pretty decent used microscope online for a couple hundred bucks. You can also find a serviceable used centrifuge priced in that range as well.

I’ve spent many years peering into microscopes, and I’ll offer this caveat regarding their use. There’s a learning curve. You’ll have to spend some time becoming proficient. Then, when you’ve figured out the microscope, you’ll need to know what you’re looking for.  While you can find pictures of a variety of worm eggs in The Chicken Health Handbook and online, there are lots of different worm species that could be infesting your flock. And worm eggs come in a variety of sizes and shapes depending on the species. They often look similar to each other and to plant cells and other debris that may be present. Again, there’s a learning curve.

If you aren’t willing to invest in the time and expense you would need to accomplish do-it-yourself testing, go to the professionals. There are two options.

Check With Your Local Vet

Most vet clinics do fecal parasite screening even if they don’t see chickens. Some vets that don’t do the testing on-site will send samples out to an affiliated reference lab for testing. So, contact your local vet clinic! They’ll tell you how to collect the sample and how to bring it to the clinic.

Send A Sample to A Testing Lab

By sending a fecal sample from your flock directly to a lab, you skip the middleman (the vet clinic). You can quickly find a list of labs by doing a Google search for “veterinary parasite testing labs.” Bear in mind, that while this may be a less expensive option than going to a vet, if the results are positive, you should consult with a vet for interpretation of the results and treatment guidance.