First approach validating a scoring system for foot-pad dermatitis in broiler chickens developed for application in...

Area of Science:

• Animal Science
• Veterinary Pathology
• Poultry Husbandry

Background:

• Foot-pad dermatitis (FPD) severity scoring is crucial for monitoring animal husbandry and welfare in poultry.
• Existing visual scoring schemes lack standardization and validation, hindering objective welfare assessment and inter-study comparisons.
• Histological validation offers a more objective approach to complement visual FPD assessments.

Purpose of the Study:

• To validate a widely used visual scoring system for foot-pad dermatitis in broiler chickens (ROSS 308) using histological measurements.
• To assess the reliability and objectivity of visual FPD scoring by comparing it with histopathological findings.
• To identify reliable visual parameters for accurately judging FPD severity.

Main Methods:

• Visual scoring of broiler feet at the slaughter plant using a 4-point scale.
• Macroscopic and microscopic analysis of sampled feet (n=40) representing each score level.
• Cluster analysis of histopathological data for classification, interobserver reliability testing, and McNemar's test for comparing visual and cluster classifications.
• Kendall tau correlations to identify reliable visual parameters for severity assessment.

Main Results:

• High agreement between observers and classifications for mild FPD scores (1 and 2).
• Divergent results for severe FPD scores (3 and 4) in both interobserver reliability and classification comparisons.
• Significant interaction effects between classification type and score level for ulcer width and lesion size.
• Histological findings correlated well with less severe visual scores; severe scores (3 and 4) showed less valid differentiation.
• Positive correlation (0.73) found between lesion size and ulcer depth.

Conclusions:

• Histological validation supports the reliability of visual scoring for mild FPD but highlights limitations in differentiating severe cases.
• Simplifying visual scoring systems is recommended for practical and more accurate poultry welfare assessment.
• Lesion size, due to its high correlation with ulcer depth, may serve as an indirect indicator of FPD severity.