Table of Contents

• Parasites and Gut Ailments
• Respiratory and Viral Diseases
• Bacterial Infections and Others
• Foot and Skin Issues
• Reproductive & Other Ailments
• Prevention and General Care
• FAQs

Raising backyard chickens is fun until one of your hens starts acting strange – it can be a panic moment! From my first batch of chicks, I’ve learned that knowing the common chicken diseases can save you a lot of headaches (and chicken feed!). In this article I’ll cluck through the most common chicken diseases and ailments, explain them in plain English (no PhD in veterinary science needed!), and add a dash of humor because… well, chickens are hilarious. Whether you’re a first-time chick-tender or a seasoned clucker, you’ll find tips to spot problems early and care for your flock’s health.

Parasites and Gut Ailments

Parasites are a chicken’s worst uninvited houseguests. Mites, lice, worms, ticks, and protozoa (tiny one-celled critters) are common chicken parasites. In fact, the Merck Veterinary Manual notes that the “common parasites in poultry are mites, lice, ticks, worms, and protozoa”. Red and northern fowl mites can crawl under feathers and make chickens itch (and give them anemia), while lice nibble on feathers at the base and make your hen very crabby. My northern mite stories: one spring I found clumps of dirt under a hen; those were mites feasting away!

Internal parasites (worms) often lurk in the gut. Roundworms and tapeworms are the most common internal poultry worms. Nearly every flock has a few, but heavy infestations can make chickens lose weight or have skinny flanks. Because worms can be sneaky, vets often recommend a yearly fecal check and routine dewormer as a benchmark for your flock’s health. (Tip: Always get label-approved poultry dewormers. Don’t give dog wormer to chickens!)

Coccidiosis is a big one, especially in younger chickens. This gut infection is caused by protozoa (little one-celled parasites) that love dirty, damp bedding. As Merck explains, “control of coccidia is one of the more common and costly problems” in chickens. Young chicks (1–4 months old) are most at risk. Symptoms include white or bloody diarrhea, lethargy, and not eating – basically, your chicken might look miserable and lame, even falling over. (I once thought my pullet was on her deathbed until I discovered coccidiosis; after treatment and fresh pine shavings, she bounced right back.) Prevention tips: keep the coop dry, don’t overcrowd, and consider medicated starter feed or coccidiostat in water if you see an outbreak.

Preventing mites and lice takes diligence, too. Check vents and under wings – Northern fowl mites look like tiny reddish specs around the vent. Nighttime red mites hide in coop cracks and bite sleeping chickens. If you see feather loss or constant scratching, it’s time to act. Good poultry dust (like diatomaceous earth or permethrin-based powders) on the roosts and in the coop, plus regular coop cleaning, can kill the little beasts. A spray like Premo Guard Poultry Spray (amazon) or Natural Parasite Control Chicken Dust can help keep mites at bay. One pellet at a time, you can shoo the bugs away!

Respiratory and Viral Diseases

Chickens don’t wear masks, so they easily catch bugs that attack their breathing. Infectious Bronchitis (IBV) is a common viral cold for chickens, especially chicks. It causes gasping, sneezing, and shrill coughing, plus nasty gunk in the trachea. Laying hens might produce oddly-shaped or wrinkled eggs if they’ve had bronchitis. Backyard birds usually fight it off with supportive care, but if you have a serious outbreak, vets sometimes add antibiotics to the water to prevent secondary infections. Vaccines exist for IBV, but they’re mostly used by commercial hatcheries – backyard flocks usually just rely on letting the birds recover.

Next up is Marek’s Disease. This one is a tumor-causing herpes virus (yes, feathers can get cancer too). Affected birds develop tumors in nerves and organs, leading to paralysis (often “range paralysis” where legs or neck go limp) or gray iris (the eye goes strange). Sadly, once chickens show symptoms of Marek’s, there’s no cure – it’s deadly. The good news? There is a vaccine given to day-old chicks that’s very effective. If you hatch or buy chicks, make sure they got their Marek’s shot, or be very vigilant for waddling, limp legs, or patches of paralysis.

Fowlpox is another viral disease with a dramatic look. Infected birds get crusty scabs and wart-like lesions on combs, wattles, or feet. The dry form (skin lesions) is unsightly but usually not lethal; the wet form (lesions in the mouth and throat) can suffocate birds. If you spot yellow-brown scabs on the comb or eyelids, think fowlpox. There is a vaccine for flocks on affected premises, and one rainy season I learned that mosquitoes spread it easily – so bug control helps, too.

Although rare in small flocks, it’s worth mentioning Avian Influenza (“bird flu”) and Newcastle Disease. Exotic strains cause high mortality and are federally monitored. Fortunately, the U.S. rarely sees those serious outbreaks; still, it’s good practice to keep your flock isolated from wild waterfowl and new birds. As always, biosecurity (quarantining new arrivals, sanitizing boots, etc.) is key to prevent viral “fowl play.”

Bacterial Infections and Other Illnesses

Bacteria can attack chickens in several ways. Colibacillosis (E. coli infection) often strikes birds already weakened by something else, like a cold or stress. In fact, Merck notes E. coli infections in backyard birds are usually secondary to other infections such as bronchitis or mycoplasma. Sick birds might show swollen sinuses, green mucus, or hard breathing. Prevention is mostly sanitation – keep feeders clean, water fresh, and coop tidy. Early antibiotic treatment can help, but be sure to use only poultry-approved meds (and always follow withdrawal times for eggs).

Mycoplasmosis (a.k.a. Chronic Respiratory Disease) is another biggie in chickens and turkeys. It’s caused by Mycoplasma gallisepticum and makes chickens sniffle, sneeze, and eat poorly over weeks. An infected flock might have swollen eyes or sinus drip (especially turkeys get puffy faces). Once a flock has Mycoplasma, it’s hard to eliminate without culling and cleaning; intensive disinfection and a break from keeping birds on the same run are recommended. Some people opt for medication, but the disease often reappears when treatment stops. I’ve found it best to buy only certified clean chicks and replace old carriers.

Salmonella infections are not just a human risk from eggs – chickens get hit too. Backyard poultry commonly see S. Pullorum and S. Gallinarum (causing Pullorum disease and Fowl Typhoid). These cause severe diarrhea and high chick mortality. Adult hens can carry Salmonella without looking sick, which is why outbreaks in people from handling chicks are frequent. In short: never eat raw egg or snuggle a chick without washing hands first! The CDC even notes Salmonella outbreaks linked to backyard flocks are common. Prevention: buy chicks from NPIP certified hatcheries (they test for Pullorum/Typhoid) and maintain scrupulous coop hygiene. If Salmonella does appear, the only sure fix is depopulation and full clean-out (no one wants “salmonella spa” in the nest box).

Other bacterial/fungal issues: In humid coops, Aspergillus mold can cause “brooder pneumonia” in chicks (sudden gasping and death). Thrush (Candida) can infect the vent (called vent gleet) often after antibiotic use. And pasty butt (sticky chick poop on a chick’s vent) isn’t a disease per se but can suffocate baby chicks if not wiped off in time. Bottom line: hygiene and good nutrition keep these at bay. If you must, I’ve used tea-tree oil soaks (with vet OK) for thrush or just gentle soap water for pasty butt – it’s usually a quick fix.

When injuries happen (think peck wounds, bites, or a wart on a foot known as bumblefoot), an antiseptic spray can be a big help. I keep a bottle of Vetericyn Poultry Spray (amazon) on hand. It’s labeled for chickens and helps keep wounds clean without stinging. For example, if a hen pecks herself bleeding – preening gone wrong – a quick spray and bandage can prevent an infection from taking hold.

Foot and Skin Issues (Bumblefoot, Scaly Leg)

Chickens love to roost and scratch, but feet and legs often pay the price. Bumblefoot is a prime example: a bacterial infection (usually Staph) of the foot pad. It starts as a minor cut or spike that gets infected into an abscess. My own “Henrietta” once limped around – I thought she had a fracture until I noticed a hard round lesion on her foot. A few treatments later (cleaning, Vetricyn, and better roost padding), she was back to normal. If you see swelling or a black scab on a foot, treat it fast – see our Bumblefoot in Chickens treatment guide for the full step-by-step. Don’t ignore it, or the chicken might stop roosting on that leg.

Scaly leg mite is another creepy-crawler. These mites burrow under the scales of a chicken’s legs and shins, causing crusty, rough scales and thickened legs. The cure is simple but must be done carefully: daily baths in soapy warm water followed by an oily treatment (like petroleum jelly or vegetable oil) on the legs to smother the mites. I’ve had hens whose legs nearly fused shut from mites – the oil therapy gradually loosened the crust and let the mites fall off. Consistency is key: treat daily for a week, then weekly for a month, and your hens’ legs will look smooth again.

Reproductive and Other Ailments

Egg-laying comes with its own set of problems. Egg binding (when an egg gets stuck) can be life-threatening. A hen will strain and act very distressed. Often it’s caused by a calcium deficiency or obesity. Prevent by providing plenty of crushed oyster shell (calcium supplement) and keeping hens active. If it happens, a warm bath and gentle massage around the abdomen can encourage the egg out – and if that fails, vet attention is needed immediately.

Egg peritonitis is related – sometimes eggs break inside and cause infection. A hen with peritonitis will be off feed, lethargic, and her belly may look swollen. Sadly, prognosis is poor, and infected hens often have to be euthanized for humane reasons.

Vent prolapse (when a hen essentially turns her vent inside out, often after laying a very large egg) can sometimes be fixed by carefully pushing it back and giving lubrication, but preventing it is better: avoid overweight birds and very large eggs in middle-aged hens.

Finally, keep an eye on nutrition deficiencies. Rickets (weak legs in chicks) can come from lack of vitamins D/calcium. The cure: make sure chicks have vitamin supplement in water and access to grit so they can absorb nutrients. Also, bad feed (moldy or watery feed) can cause crop stasis (“sour crop”), which smells bad. Gentle exercise and clean warm water fasting usually clears it.

Prevention and General Care

The best defense is a good offense. Keep coops clean and dry, freshen bedding regularly, and don’t let feed get wet. Provide fresh water daily (electrolytes or apple cider vinegar in water during heat waves can help) and a balanced diet with supplements as needed. For example, Tractor Supply carries a Purina Electrolyte & Antioxidant supplement for poultry that I’ve used when my girls look a bit off on hot days. Always isolate new or sick birds and disinfect your hands and boots between flocks.

Routine observation is huge. Spend time with your chickens. I can tell within minutes of entering my run if someone’s not feeling well – I look for fluffed feathers, droopy heads, dirty vents, or odd droppings. A healthy chicken is alert, curious, and has bright eyes and a red comb. If anything seems off, separate the bird and check it out. Quick intervention can turn a crisis into a minor fix (like catching coccidiosis on day one rather than day five).

Vaccinations: Besides Marek’s in chicks, most backyard flocks don’t do much vaccinating. But if you’re starting a flock from day-old chicks, look for Marek’s vaccine or talk to your hatchery about shot chicks. Some people vaccinate for Newcastle or Infectious Bronchitis, but that’s usually for larger or trading flocks.

Coop maintenance products are also handy. For instance, I sanitize with a coop cleaner like Microbe-Lift Chicken Coop Cleaner to kill bacteria and make the manure safe to compost. Tractor Supply sells FlockLeader Healthy Coop Cleaner as well. Using these after a flock turn-over keeps pathogens down. A good dust bath area (wood ash or sand) inside the run can naturally deter mites and lice.

Probiotics can boost gut health and immunity. I use a poultry probiotic like UltraCruz Poultry Probiotic powder in their water or feed occasionally; it’s available on Amazon. It’s a cheap insurance policy for keeping chickens’ stomachs in balance during stress (new chicks, antibiotic courses, etc.).

In short, there’s no magic. Keep things clean, feed them well, give fresh air and sunshine, and your chickens will be in tip-top cluck. And remember: when something goes wrong (because it eventually will), quick response is key. Your cluckopedia (that’s you, dear reader!) will thank you with healthy eggs and happy chickens.

FAQs

Q1: How can I prevent these common chicken diseases?
A: The holy trinity of prevention is clean, diet, and observation. Clean your coop, feeders, and waterers regularly (disinfect if an illness hit). Feed a balanced diet with grit and supplements (calcium, vitamins) as needed. Observe your birds daily so you catch symptoms early. Practice biosecurity: quarantine new birds, avoid visitors if sick poultry are nearby, and wash hands after handling chickens or eggs.

Q2: My hen is listless and off her feed – what should I do?
A: A lot could cause that. First, isolate her from the flock and do a quick check: feel for lumps, check vent for pasting, look at crop (if it feels hard, she might have sour crop), and see if her eyes or nostrils have discharge. Offer fresh water with electrolytes. If she’s breathing hard or has obvious wounds, treat those specifically (clean wounds, give Vetricyn). If symptoms are severe or worsen in 24 hours, call a vet experienced with poultry. Early treatment with dewormers, antibiotics, or electrolytes often turns things around.

Q3: Can chicken diseases spread to humans?
A: Some can! Salmonella and Campylobacter are the main human health concerns from poultry. Washing hands, keeping coops separate, and cooking eggs/ meat properly are key. Most bird-specific viruses (like Marek’s or IBV) do not infect people. But always practice good hygiene around chickens – as the CDC notes, even healthy-looking birds can carry germs that sicken people.

Q4: Do I need a vet for chicken diseases?
A: Not always, but it helps. For minor issues (pasty butt chicks, slight respiratory rales), a home remedy might suffice. For severe or unclear problems (high mortality, neurological signs, or reproductive failures), contact a vet or extension agent. Many poultry keepers call about things like Marek’s symptoms or cocci outbreaks. Having a good chicken book (or cluckopedia!) on hand, plus a vet line or online poultry community, is invaluable. Prevention and quick action are your best tools; think of a vet as your backup plan.

Q5: What products can help keep my flock healthy?
A: There are many helpful tools: coop and litter cleaners, probiotics, supplements, and parasite treatments. Some favorites include a coop cleaner Microbe-Lift, UltraCruz Poultry Probiotic, poultry mite dusts or sprays like Premo Guard spray or Tractor’s parasiticide dust, and electrolytes/vitamins like Electrolyte packets. Never forget basic items: fresh feeder, clean waterer, good grit and oyster shell, and a quality poultry first aid kit with things like Vetericyn or wound spray. These aren’t magic bullets, but they give you a leg up in prevention and early treatment. When used properly, they keep your flock clucking happily along!