Characteristic posture of a chicken with Marek's disease showing extension of one leg and retraction of the other

Unilateral enlargement of nerve of the sciatic plexus is characteristic of Marek's disease

Keratitis and conjunctivitis following exposure to high levels of atmospheric ammonia

Accumulation of purulent material in the infraorbital sinus is characteristic of coryza

Ocular discharge and swelling of nasal sinus associated with coryza. Differential diagnosis includes mycoplasmosis or laryngotracheitis

Acute onset of ocular discharge accompanied by high flock morbidity may denote infectious larngotracheitis, infectious bronchitis, coryza or mild avian influenza

'Swollen Head Syndrome' in broiler showing cellulitis of the face and head with symblepharon (closed eyes)

Broiler with swollen face and dyspnea due to laryngotracheitis

Enlarged Bursa of Fabricius typical of acute infectious bursal disease. Note urate accumulation on vent plumage and enlarged kidneys

Characteristic subcutaneous and intramuscular hemorrhages associated with infectious bursal disease

Acute infectious bursal disease showing chicken with copious white diarrhea

Haemorrhage and transudate beneath the wing associated with transduative diathesis due to destruction of Vitamin E following oxidative rancidity

Chicks showing edema of intamandibular region due to transduative diathesis

Broiler chicks approximately 14-days old showing lateral recumbency associated with nutritional encephalomalacia

Hemorrhage within the cerebellum characteristic of nutritional enchepalomalacia due to Vitamin E deficiency

Advanced dermatitis of the feet (scaly leg) due to Knemidocoptes mutans infestation

Hyperkeratosis of the planter surface of the feet associated with pantothenic acid or biotin deficiency

The long bones of chicks with rickets can be bent without fracture

Vent peck and disembowelment in cage-housed hens can be avoided by careful beak trimming and control of light intensity

Enlarged yellow yolk sac, typical of omphalitis in a 3 day old chick

Grossly enlarged yolk sac of a chick showing red tinged contents associated with omphalitis

Regression of the ovary in a mature hen due to Salmonella pullorum infection