Thorough individual observation throughout the entire process can greatly improve the accuracy of disease diagnosis. After basic checks of body temperature and the respiratory tract, the chicken’s external appearance, body surface, and limb movement and posture provide important clues for identifying chronic diseases, nutritional and metabolic diseases, and viral diseases.
 
　　To help poultry farmers master techniques for observing chickens’ appearance and posture, this issue of the Smart Laying Hens Hot Topics column focuses on practical ways to identify abnormalities in the comb and wattles, eyelids, skin and feathers, abdomen, and limb movement, making the guidance easy to apply in practice.
 
　　Question 1: What do a healthy chicken’s comb and wattles look like? What diseases are associated with swelling, paleness, atrophy, and purplish discoloration, respectively?
 
　　A healthy chicken’s comb and wattles are bright red and moist, and feel warm to the touch.
 
　　Swelling is commonly seen with fowl cholera, avian influenza, Escherichia coli infection, or stress from vaccination. Pale color without atrophy suggests white-comb disease, coccidiosis, or internal bleeding. Yellowing and atrophy of the comb and wattles are associated with wasting diseases such as Marek’s disease and lymphoid leukosis. Dark red or cyanotic discoloration is often associated with Newcastle disease or respiratory disease. A blue-purple comb and wattles raise strong suspicion of H5 subtype influenza. Raised pox lesions on the surface indicate fowlpox.
 
　　Question 2: What are the causes of tearing, swelling, cloudiness, and eyes that are half-open or half-closed?
 
　　Bright, alert eyes in chickens indicate good health.
 
　　Eyes that are half-open or half-closed, with narrowed slits, are often associated with excessive ammonia or formaldehyde levels, or infectious laryngotracheitis; persistent tearing that stains the feathers around the eyes occurs with rhinitis, mycoplasmosis, or fowlpox; eyelid adhesion with yellow, cheesy material accumulating inside is caused by Mycoplasma, vitamin A deficiency, or Escherichia coli; white corneal spots and ulcers are typical symptoms of ocular Marek’s disease; raised pockmarks on the conjunctiva indicate the mucosal form of fowlpox.
 
　　Question 3: How can disease types be distinguished when there is facial swelling?
 
　　A rosy, lustrous face is a sign of health in laying hens.
 
Warm to the touch, with fluctuating swelling, usually indicates fowl cholera or infectious laryngotracheitis; hard, non-fluctuating swelling should be checked for mycoplasmosis, avian influenza, or rhinitis; bilateral infraorbital sinus swelling is generally mycoplasmal sinusitis.
 
Question 4: What problems do ruffled feathers, skin tumors, a blackened navel, and subcutaneous emphysema indicate, respectively?
 
　　Drooping, dull wings indicate long-term malnutrition; raised feathers indicate high fever and chills; extensive feather loss and bald patches are usually caused by vitamin A deficiency or external parasites. Raised, hard skin tumors indicate the cutaneous form of Marek’s disease; a dark, hardened navel in chicks indicates omphalitis caused by Salmonella or E. coli; balloon-like swelling under the skin is caused by air entering after trauma ruptures an air sac.
 
　　Question 5: What causes abdominal enlargement versus shrinkage when touched?
 
　　In healthy chickens, the abdomen is soft and elastic, and the muscular stomach and edge of the liver can be felt. A shrunken abdomen is usually associated with reduced feed intake and hens ceasing production. In laying hens, an enlarged abdomen and a waddling, penguin-like gait, with a fluctuant sensation on palpation, indicate fluid and eggs accumulating in the oviduct due to infectious bronchitis or mycoplasma. A hard, enlarged abdomen in chicks is caused by poor yolk absorption, stemming from low temperatures, Salmonella, or Escherichia coli.
 
　　Question 6: Which diseases correspond to abnormal movement postures such as lameness, legs splayed apart, head twisting, a penguin-like gait, and paralysis?
 
　　Lameness is often caused by calcium-phosphorus imbalance, vitamin D deficiency, Mycoplasma synoviae, or gout; splits in young chickens and drooping wings are signs of the nervous form of Marek’s disease; twisting of the head and neck after being startled is a sequela of Newcastle disease; unilateral paralysis and head tremors in chicks are signs of avian encephalomyelitis; manganese deficiency causes enlarged joints and elbow varus; a penguin-like gait is caused by permanent oviduct damage and the accumulation of large amounts of caseous material; paralysis with both legs extended backward in laying hens in the early morning is cage layer fatigue; a dog-sitting posture with difficulty breathing is commonly seen with aspergillosis and infectious laryngotracheitis; improper catching during flock transfer can directly cause fractures.
 
　　The appearance of the chickens’ bodies and their movement and posture provide visible clues for assessing flock health. During inspections, check each bird in sequence: comb and wattles, eyes, skin, abdomen, and limbs. Combine multiple external symptoms to make a more accurate assessment.