Common Health Conditions in Chickens: What Every Poultry Keeper Should Know

Keeping chickens can be an incredibly rewarding experience, whether you're running a smallholding, managing a backyard flock, or overseeing a larger poultry operation. However, as with any animals, chickens are prone to various health conditions. Early detection, preventive care, and appropriate treatment are essential to ensure your birds remain healthy and productive.

This guide outlines the most common chicken health issues, their symptoms, causes, treatments, and preventive measures.

Marek’s Disease

Overview

Marek’s disease is a highly contagious viral illness caused by a herpesvirus. It primarily affects young chickens and can lead to paralysis and tumours.

Symptoms

• Progressive paralysis (wings, legs, neck)
• Weight loss
• Tumours in internal organs
• Blindness (in ocular form)
• Irregular pupils

Transmission

• Spread through dander and feather debris
• Enters via inhalation

Treatment

• No cure once infected
• Euthanasia is often recommended for affected birds

Prevention

• Vaccinate chicks at day-old
• Maintain strict biosecurity
• Keep brooder areas clean and dry

Coccidiosis

Overview

Coccidiosis is a parasitic disease caused by protozoa, common in young or stressed birds.

Symptoms

• Bloody or watery diarrhoea
• Lethargy
• Drooping wings
• Pale combs
• Poor growth

Transmission

• Ingesting contaminated litter or feed
• Poor hygiene and overcrowding increase risk

Treatment

• Anticoccidial medications (e.g., Amprolium)
• Isolate affected birds

Prevention

• Use medicated chick starter feed
• Regularly clean housing
• Rotate pasture if free-ranging

Infectious Bronchitis

Overview

Infectious bronchitis is a viral respiratory disease affecting chickens of all ages. It spreads rapidly and affects the respiratory tract, reproductive system, and kidneys.

Symptoms

• Sneezing and coughing
• Nasal discharge
• Watery eyes
• Drop in egg production
• Misshapen or thin-shelled eggs

Transmission

• Airborne or via contaminated equipment and clothing

Treatment

• No specific antiviral treatment
• Provide supportive care (warmth, fluids, vitamins)

Prevention

• Vaccination
• Strong biosecurity protocols
• Good ventilation in coops

Avian Influenza

Overview

Avian influenza is a highly contagious viral disease with the potential to cause large-scale outbreaks and high mortality rates.

Symptoms

• Sudden death
• Swollen comb and wattles
• Respiratory distress
• Diarrhoea
• Nervous signs (in severe cases)

Transmission

• Wild birds are major carriers
• Spread through droppings, saliva, or contaminated equipment

Treatment

• No treatment; notifiable disease
• Flocks may need to be culled

Prevention

• Keep chickens away from wild birds
• Implement strict quarantine and hygiene protocols
• Report suspected cases to authorities

Fowl Pox

Overview

Fowl pox is a slow-spreading viral disease in two forms: dry (cutaneous) and wet (diphtheritic).

Symptoms

• Scabby lesions on comb, wattles, and beak
• Yellow plaques inside mouth or windpipe (wet form)
• Drop in appetite and egg laying

Transmission

• Spread via mosquito bites or contact with scabs

Treatment

• Supportive care
• Remove affected birds during outbreaks

Prevention

• Vaccinate birds, especially in mosquito-prone areas
• Control insect populations

Infectious Laryngotracheitis (ILT)

Overview

ILT is a serious respiratory disease caused by a herpesvirus.

Symptoms

• Gasping and coughing
• Nasal and eye discharge
• Blood-stained mucus
• Drop in egg production

Transmission

• Spread through respiratory secretions and equipment

Treatment

• No specific treatment
• Supportive care and culling of severe cases

Prevention

• Vaccination
• Isolate new birds and maintain biosecurity

Botulism

Overview

Botulism is a potentially fatal illness caused by toxins from Clostridium botulinum bacteria.

Symptoms

• Sudden flaccid paralysis
• Limp neck (limberneck)
• Inability to walk, eat or drink
• Death within hours in severe cases

Causes

• Ingesting decaying organic matter or contaminated carcasses

Treatment

• Antitoxin if caught early
• Supportive care with fluids and feeding

Prevention

• Keep run and coop free of dead animals and rotting materials

Egg Binding

Overview

Egg binding occurs when a hen is unable to pass an egg. It can be life-threatening if not addressed quickly.

Symptoms

• Straining
• Lethargy
• Swollen abdomen
• Tail down posture
• Loss of appetite

Causes

• Poor nutrition (lack of calcium)
• Overweight hens
• Young or older birds
• Large or misshapen eggs

Treatment

• Warm baths and gentle massage
• Calcium supplements
• Veterinary intervention may be necessary

Prevention

• Provide a well-balanced diet with adequate calcium
• Maintain good body condition
• Reduce stress in laying hens

Scaly Leg Mites

Overview

Scaly leg mites are microscopic parasites that burrow under the scales on a chicken’s legs and feet.

Symptoms

• Raised, crusty leg scales
• Lameness
• Swelling and inflammation
• Thickened legs over time

Transmission

• Spread through contact with infested birds or housing

Treatment

• Soak and gently scrub legs
• Apply topical treatments (e.g., ivermectin, petroleum jelly)
• Disinfect coop and perches

Prevention

• Regular health checks
• Maintain clean and dry living conditions
• Quarantine new birds

Bumblefoot

Overview

Bumblefoot is a bacterial infection (often Staphylococcus) of the foot, usually entering through a cut or abrasion.

Symptoms

• Swollen footpad
• Hard, black scab
• Limping
• Reluctance to perch or walk

Causes

• Rough or dirty perches
• Sharp objects in the run
• Obesity and inactivity

Treatment

• Clean wound and apply antiseptics
• In severe cases, veterinary surgery may be needed
• Antibiotics if prescribed

Prevention

• Provide soft, smooth perches
• Inspect runs and coops for sharp objects
• Keep bedding clean and dry

Worm Infestation

Overview

Chickens can be affected by several internal parasites, including roundworms, tapeworms, and gapeworms.

Symptoms

• Weight loss
• Pale combs
• Diarrhoea
• Poor egg production
• Gasping (in gapeworm infections)

Transmission

• Picking up parasite eggs from droppings or soil

Treatment

• Use poultry-approved wormers (e.g., Flubenvet)
• Repeat treatment as advised

Prevention

• Rotate grazing areas
• Clean droppings frequently
• Conduct regular faecal checks

External Parasites: Lice and Mites

Overview

External parasites are a common issue, particularly in warm or crowded environments.

Symptoms

• Feather loss
• Excessive preening
• Irritated or red skin
• Decreased egg production
• Visible lice or mites, especially around vent

Types

• Red mites (feed at night)
• Northern fowl mites
• Poultry lice

Treatment

• Dust or spray with poultry-safe insecticides
• Repeat treatments to break lifecycle
• Clean and treat coop, especially cracks and perches

Prevention

• Regular inspections
• Diatomaceous earth in dust baths
• Good coop hygiene

Newcastle Disease

Overview

Newcastle disease is a serious viral disease that affects the respiratory, digestive, and nervous systems.

Symptoms

• Coughing, sneezing, gasping
• Diarrhoea
• Twisted neck (torticollis)
• Paralysis
• Drop in egg production

Transmission

• Direct contact with infected birds or materials
• Contaminated equipment or humans

Treatment

• No cure available
• Supportive care only

Prevention

• Vaccination
• Quarantine new birds
• Biosecurity measures

Infectious Coryza

Overview

Infectious coryza is a bacterial disease causing upper respiratory infection, especially in adult birds.

Symptoms

• Swelling of the face and wattles
• Foul-smelling nasal discharge
• Sneezing and conjunctivitis
• Decreased feed intake and egg production

Transmission

• Direct contact or through contaminated feed, water, or bedding

Treatment

• Antibiotics may help but birds remain carriers
• Cull in severe outbreaks

Prevention

• Quarantine new additions
• Keep water and feeders clean
• Avoid overcrowding

Mycoplasma (CRD)

Overview

Chronic respiratory disease (CRD) is caused by Mycoplasma gallisepticum, often in combination with other infections.

Symptoms

• Coughing and nasal discharge
• Swollen sinuses
• Conjunctivitis
• Slow growth or poor egg production

Transmission

• Bird-to-bird contact
• Contaminated equipment

Treatment

• Antibiotics can control symptoms
• Birds often remain carriers

Prevention

• Obtain stock from disease-free sources
• Isolate sick birds
• Practice strict biosecurity

Crop Impaction

Overview

Crop impaction occurs when the crop becomes blocked by indigestible material.

Symptoms

• Full, hard crop even in the morning
• Reduced appetite
• Lethargy
• Sour-smelling breath

Causes

• Eating long grass, hay, or foreign objects

Treatment

• Gentle massage and administering vegetable oil
• Surgical removal in severe cases

Prevention

• Monitor access to long grass
• Provide grit to aid digestion

Sour Crop

Overview

Sour crop is a yeast infection (usually Candida albicans) in the crop.

Symptoms

• Foul-smelling breath
• Squishy, enlarged crop
• Lethargy
• Loss of appetite

Causes

• Overeating, poor diet, or crop impaction

Treatment

• Withhold food for 24 hours, offer water with apple cider vinegar
• Administer antifungal treatment

Prevention

• Clean feeders and waterers
• Provide balanced diet

Heat Stress

Overview

Heat stress occurs when chickens cannot regulate their body temperature in hot conditions.

Symptoms

• Panting and spreading wings
• Lethargy
• Reduced egg production
• Collapse or death in extreme cases

Treatment

• Move birds to shade
• Provide cool water with electrolytes
• Mist lightly with water

Prevention

• Provide ventilation and shade
• Use frozen treats and fresh water

Vent Gleet (Cloacitis)

Overview

Vent gleet is a yeast or bacterial infection of the vent area.

Symptoms

• Foul-smelling discharge around the vent
• Dirty feathers
• Red, swollen vent
• Decreased egg laying

Treatment

• Clean vent with saline
• Apply antifungal or antibacterial ointment
• Offer probiotic supplements

Prevention

• Maintain hygiene and stress-free environment
• Feed a balanced diet

Twisted Neck (Wry Neck)

Overview

Wry neck is a neurological condition where the bird cannot hold its head upright.

Symptoms

• Twisting of the head and neck
• Inability to eat or drink normally
• Rolling or walking in circles

Causes

• Vitamin E deficiency
• Head injury
• Certain viral infections

Treatment

• Administer vitamin E and selenium supplements
• Supportive care and isolation

Prevention

• Feed a complete, vitamin-rich diet
• Avoid overcrowding and rough handling

Gumboro Disease (Infectious Bursal Disease)

Overview

Gumboro is a viral disease affecting the immune system of young chickens.

Symptoms

• Ruffled feathers
• Diarrhoea
• Trembling
• Dehydration
• Immunosuppression leading to other infections

Transmission

• Through droppings and contaminated surfaces

Treatment

• No specific cure; supportive care

Prevention

• Vaccinate chicks
• Maintain hygiene and biosecurity

Erysipelas

Overview

Erysipelas is a bacterial infection caused by Erysipelothrix rhusiopathiae.

Symptoms

• Sudden death
• Swollen joints
• Darkened combs
• Lameness

Transmission

• Contaminated soil, water, or dead birds

Treatment

• Antibiotics such as penicillin
• Isolate affected birds

Prevention

• Rotate pastures
• Dispose of carcasses promptly
• Vaccination available in some areas

Conclusion

Understanding the full spectrum of common and uncommon health conditions that affect chickens is essential for any poultry keeper. Early recognition and proper management can mean the difference between life and death for a bird, or between a minor setback and a flock-wide outbreak. Regular observation, clean housing, appropriate nutrition, vaccinations, and strict biosecurity are your best defences against disease. Always consult a poultry-savvy vet if you’re unsure—your flock’s health depends on it.