Common Chicken Ailments O-Z

Here is a continuation of the common chicken ailments section. This selection is the diseases that are O-Z.

To Common Ailments A-C To Common Ailments D-N


Incidence: common chicken ailment

System/organ affected: navel

Symptoms: dead embryos late in incubation; newly hatched chicks feel wet. In chicks: drooping head, huddling near heat, lack of uniformity in size, lack of interest in food or water, mushy or scabby navel.

Cause: bacteria

Transmission: contaminated droppings on hatching eggs. high incubation humidity, infectious material in incubator, feed or water contaminated with droppings.

Prevention: hatch only eggs that have no cracks, and are clean. Control incubator humidity, clean and disinfect incubator.

Treatment: non effective.


Incidence: common chicken ailment

System/organ affected: bones

Symptoms: thickened leg bones, puffy looking shanks, lameness.

Cause: retrovirus

Transmission: contact with infected birds; spread by infected breeders through hatching eggs or from infected chicks to non-infected chicks through droppings, blood-sucking parasites.

Prevention: buying and breeding resistant strands.

Treatment: none; cull


Incidence: very common chicken ailment worldwide

System/organ affected: digestive or entire body

Symptoms: in embryos: numerous dead in shell at hatch. In chicks: death at time of hatch or depression, weakness, poor growth, drooping wings, increased appetite, increased thirst, huddling around heat with feathers ruffled.

Cause: Bacteria (salmonella)

Transmission: contaminated soil or litter (can persist for up to seven months), etc.

Prevention: difficult, due to the bacteria's wide range of animal hosts.

Treatment: none effective, survivors may be carriers. This disease must be reported to the federal public health administration.

Pasted Vent

Incidence: common in chicks, less common in mature birds.

System/organ affected: vent

Symptoms: in chicks: droopiness, droppings sticking to vent. In laying hens: offensive odor from droppings sticking to vent feathers.

Cause: unknown

Transmission: does not spread from bird to bird

Prevention: keep chicks warm and do not hatch eggs from affected hens.

Treatment: carefully pick away the matter stuck to the vent. Cull chicks that don't recover.

Pox (dry)

Incidence: common chicken ailment in some areas worldwide, especially in confined flocks in cold weather.

System/organ affected: skin

Symptoms: raised clear or whitish wart-like bumps on comb and wattles that grow larger, turn yellowish, and later become reddish brown, grey, or black bleeding scabs appearing as singles or in clusters.

Cause: pox virus that affects a wide variety of birds and survives for many months on scabs and feathers of infected birds.

Transmission: through skin wounds, feathers and scabs from infected birds. Also spread by mites, mosquitoes, and wild birds.

Prevention: control mites and mosquitoes and vaccinate where pox is prevalent.

Treatment: none; isolate infected birds in uncrowded housing. Remove scabs around mouth and eyes where birds can eat.

Pox (wet)

Incidence: worldwide but less common than dry pox.

System/organ affected: upper respiratory

Symptoms: white and scabby bumps on face, eyes, throat and windpipe.

Cause: same virus as dry pox invading the upper respiratory tract

Transmission: same as for dry pox

Prevention: same as for dry pox

Treatment: If thick discharge interferes with breathing, clear the bird's airway with Q-tip coated with iodine. Other than that, treat much like dry pox.

Rotaviral Enteritis

Incidence: common chicken ailment worldwide and increasingly more common

System/organ affected: digestive

Symptoms: in young birds: depression, diarrhea, inflamed vent, loss of appetite, weight loss.

Cause: rotavirus common in poultry houses, but it doesn't always cause disease.

Transmission: contact with infected birds and their droppings and spreads on contaminated equipment.

Prevention: clean and disinfect housing periodically and do not start new chickens on used litter.

Treatment: none; cull.

Chicken With Slipped Tendon

Slipped Tendon

Incidence: common in heavy, fast growing breeds

Symptoms: in young birds: swollen, flat hock joint, hopping on one leg, sometimes a leg twists and rotates to the side.

Cause: deficiency in manganese or one of five B vitamins.

Transmission: nutritional, does not spread from bird to bird.

Prevention: breed for genetic resistance, feed at least 95 percent commercial ration.

Treatment: manganese and vitamin B supplement won't reverse permanent damage, but will minimize future damage.


Incidence: common in free-range flocks in tropical and temperate climates, rare in North America.

Symptoms: droopiness, ruffled feathers, huddling, diarrhea with large amounts of white urates, uncoordinated, loss of interest in perching, lying with head on ground, convulsions, fever.

Cause: bacteria; it can infect many birds but does not survive very long in the environment.

Transmission: contact with moist droppings, blood, tissue or mucus from infected birds. Also can be spread by biting insects or ticks.

Prevention: control ticks and other blood-sucking insects. Do not house clean birds where an outbreak has occurred.

Treatment: none effective.

Staphylococcic Arthritis

Incidence: common chicken ailment worldwide

System/organ affected: joints or entire body

Symptoms: fever, reluctance to move, ruffled feathers, depression, swollen joints, resting on hocks.

Cause: bacteria

Transmission: bacteria entering body through wounds

Prevention: prevent injuries by providing safe, uncrowded housing.

Treatment: staph bacteria are resistant to many antibiotics, but treatment may be sufficient if a suitable antibiotic is determined by laboratory testing.

Sudden Death Syndrome

Incidence: common chicken ailment worldwide, especially in broilers.

System/organ affected: heart and lungs

Symptoms: in apparently healthy broilers, usually males, they get extended neck, gasping or squawking, wing beating, leg pumping, flipping onto back, and then death within one minute of first symptoms. In hens: cloacal tissue goes through vent and quick death.

Cause: unknown; may be caused by high carbohydrate feeds and rapid weight gain.

Transmission: nutritional, does not go from bird to bird.

Prevention: low-intensity lighting and avoiding noise and other disruptions.

Treatment: none


Incidence: common chicken ailment

System/organ affected: upper digestive tract

Symptoms: in growing birds: depression, rough feathers, diarrhea, slow growth and weight loss

Cause: yeast like fungus commonly living in bowels of chickens that infect when normal flora are disrupted by coccidiosis or antibiotics, growth promoters, and other drugs.

Transmission: contaminated droppings in drinking water

Prevention: good nutrition and sanitation and avoiding long term treatment with antibiotics and other drugs.

Treatment: isolate infected birds and clean and disinfect feeders and waterers.


Incidence: common chicken ailment worldwide, especially in backyard flocks in temperate Northern climates.

System/organ affected: starts in intestinal tract and migrates to other internal organs.

Symptoms: mature birds: dull, ruffled feathers, gradual weight loss, shrunken breast muscles, prominent keel, persistent diarrhea, decrease in laying.

Cause: bacteria

Transmission: droppings of infected birds or picking at contaminated carcasses of dead birds, spread by shoes and equipment.

Prevention: design housing so birds can't pick in droppings, do not mix birds.

Treatment: non effective.

Ulcerative Enteritis

Incidence: common chicken ailment worldwide

System/organ affected: lower intestine and ceca

Symptoms: in young birds: sudden death with no symptoms, hunched up posture with head pulled in and eyes closed, diarrhea.

Cause: bacteria that affect game birds more often than chickens. It persists under various conditions and resists disinfectants.

Transmission: contagious; spreads in droppings of infected carrier birds picked from litter, feed, and water.

Prevention: remove and replace litter between flocks or raise birds on wire. Avoid overcrowding and manage internal and external parasites.

Treatment: strepomycin in drinking water at rate of 15 grams per gallon for ten days. All survivors may be carriers.

To Common Ailments A-C To Common Ailments D-N

From Chicken Ailments to Chicken Diseases

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