Journal of Scientific Research and Reports

Aims: To investigate the occurrence of Fatty Liver Hemorrhagic Syndrome (FLHS) and its association with concurrent Escherichia coli infection in commercial layer chickens presented for post-mortem examination.

Study Design: Cross-sectional observational study of diagnostic necropsy cases.

Place and Duration of Study: Department of Veterinary Pathology, College of Veterinary Science, PVNRTVU, Hyderabad, Telangana, India, between December 2025 and June 2026.

Methodology: A total of 280 chicken carcasses, mainly commercial layers aged 25–72 weeks, were subjected to systematic necropsy, histopathology and bacteriological culture of liver and intestinal samples. E. coli isolates were identified by cultural, morphological and biochemical (IMViC) characteristics, and 45 randomly selected representative isolates were confirmed by PCR targeting the 16S rRNA gene (585 bp). The association between FLHS and E. coli infection was analysed using Pearson's Chi-square test on a 2×2 contingency table, and the odds ratio (OR) was calculated.

Results: FLHS was diagnosed in 159 birds (56.79%) and was characterised by enlarged, pale-yellow, friable livers with subcapsular and parenchymal haemorrhages and excessive abdominal fat deposition. Histopathology confirmed severe hepatic steatosis, hepatocellular degeneration and multifocal haemorrhages. E. coli was isolated from 90 birds (32.14%), and 39 of the 45 (86.67%) representative isolates were confirmed by PCR. E. coli was recovered from 65 of 159 (40.88%) FLHS-affected birds compared with 25 of 121 (20.66%) birds without FLHS, and 72.22% of the E. coli-positive birds had concurrent FLHS. A significant association was observed between FLHS and E. coli infection (χ² = 12.88, df = 1, P < 0.001; OR = 2.66, 95% CI: 1.54–4.57). Birds with concurrent infection showed intestinal congestion, catarrhal enteritis, fibrinous perihepatitis and fibrinous pericarditis.

Conclusion: FLHS was significantly associated with concurrent E. coli infection in the examined layer chickens; however, owing to the cross-sectional design, this association does not establish causality. Integrated pathological, bacteriological and molecular diagnosis, together with appropriate nutritional, environmental and flock-health management, is recommended. Further studies on immunological mechanisms, antimicrobial susceptibility and APEC virulence genes are warranted.