Volume 16, Issue 1: 2026 - Article 209

Abstract
Neurotropic viral infections in young chicks may cause rapid neurologic disease and high mortality in unvaccinated flocks. The present case report documented clinicopathologic and histopathologic features of an acute neurologic disease outbreak in seven-day-old broiler chicks, and evaluated the relative likelihood of its aetiologic agent being avian encephalomyelitis virus (AEV) versus Newcastle disease virus (NDV). Representative freshly dead chicks from a broiler flock (n = 100) presenting clinical signs of progressive ataxia, circling and 15 deaths over seven days were necropsied. Post-mortem examination revealed minimal gross changes, limited to pulmonary congestion, mild enteritis, retained yolk sac and exudates in the abdomen. The brain (cerebrum, cerebellum, and brainstem), proventriculus and sciatic nerve were dissected out, fixed in formalin, paraffin-embedded, and stained with haematoxylin and eosin for light microscopy. Results of histology showed severe, diffuse non-suppurative leptomeningoencephalitis with dense perivascular mononuclear cuffing, endothelial swelling, extensive gliosis, neuronal degeneration and neuronophagia. Notably, the cerebellum exhibited multi-focal to coalescing granular layer necrosis with liquefactive encephalomalacia. Marked ependymal hyperplasia and subependymal lymphocytic infiltration were also present. There was no convincing transmural fibrinoid necrosis of vessels or widespread visceral necrosis or haemorrhage. In birds of this age (seven-day-old), the lesion distribution (prominent cerebellar malacia and granular cell loss), epidemiologic history (early onset, possible vertical transmission), and lack of systemic haemorrhagic or necrotizing visceral lesions favour avian encephalomyelitis virus as the most likely cause; NDV remains an important differential. This case report emphasizes the critical role of histopathology in diagnosing central nervous system disorders in poultry, and highlights the importance of early vaccination and biosecurity in preventing severe neurologic diseases in broiler flocks.

Keywords: Neurologic disease; Broiler chickens; Histopathologic diagnosis; Cerebellar malacia; Avian encephalomyelitis.

How to cite this article:
Bakre AA, Olaifa OS, Oyesiji AE and Olojede AA (2025). Cerebellar malacia in seven-day old broiler chicks: suspected case of avian encephalomyelitis. Journal of Veterinary and Applied Sciences, 16(1): 1259 – 1268.

*Correspondence: E-mail:     alaminolojede@gmail.com     Phone: +2349040645783

Cerebellar malacia in seven-day old broiler chicks: suspected case of avian encephalomyelitis
Adetolase A. Bakre ¹, Olanrewaju S. Olaifa ², Ayomikun E. Oyesiji ¹ and Al-Amin A. Olojede ¹ *

¹ Department of Veterinary Medicine, Faculty of Veterinary Medicine, University of Ibadan, Ibadan, Oyo State, Nigeria.
² Department of Veterinary Pathology, Faculty of Veterinary Medicine, University of Ibadan, Ibadan, Oyo State, Nigeria.

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